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Earthquake Seismology - Science topic

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We can calculate the dimension of a fault plane for a particular magnitude earthquake using Wells and Coppersmith (1994) relation. But how can we locate it on map.  
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I am also seeking answers to this question in 2022.
Has anyone been able to obtain a definite procedure to estimate the location of the surface projection of a buried fault plane?
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Hi,
I need the digitized data (Acceleration time history) of 1968 Tokachi-Oki Earthquake (Hachinohe harbor).
Here you can see the graph of this record (Acc. time history) that used in this article:
And also an old report of this event is available in Port and Airport Research Institute of Japan website: [pari.go.jp] (Strong-Motion Earthquake Records on The 1968 Tokachi-Oki Earthquake And Its Aftershocks)
I wonder if someone can help me find this record. Thanks.
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Do you find it. Could you send me a copy? I find a record but the time seems to be the right.
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This topic has been open for a wide range of researchers here and outside of RG, as open access to write and read comments related.
I encourage researchers with a deterministic view on earthquake nature for being proactive by trying to use resources of this space as much as possible in a way of understanding this phenomena by challenging their forecast models through forecast tests.
On forecast, I would like to find the method, data and time window for forecast, with magnitude range and probability of occurence. If the location of future event is possible, please specify. It's a test, and additional option to write about our successful forecasts and our correct models.
Also, please be concise, as possible.
In addition, I suggest to make references to own research, or other sources, for keeping the transparency on sensitive questions such as autor rights, originality and other aspect. For this, in case of not published yet ideas, I suggest to publish and come down in the comments with reference to official open to public source - article.
N.B. Regarding the forecasts based on statistical methods, and random nature of the EQ phenomenon view, are also welcomed.
Sincerely,
Sandu I.
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Dear Sandu,
You have right, In the zone happened three earthquakes around 'M: 7.4' onto the base of Google map see the attached file.
Regards,
Laszlo
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Dear researchers
What is your opinion about the criterion recommended in seismic codes for determining scaling period, which are used to scale ground motion records?
As you know, the mentioned criterion is the period of the structure’s dominant mode, which has the largest modal participating mass ratio (usually the first vibration mode). Hence, the period of the mode with the second largest modal participating mass ratio is not considered in the scaling process. Consequently, although this criterion usually results in the largest value of scaling period, it is not logical ones.
This is especially important when Tuned Mass damper (TMD) or Base-Isolation system is utilized, which cause the modal properties of the structures to change.
I used a new criterion based on the weighted mean value of the periods for the structures equipped with TMD.
Have you used any criteria other than the criterion mentioned in the seismic codes?
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Dear Mikayel Gregor Melkumyan , it is my pleasure if u can read my latest article
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Actually I've had done it, but the result only show tsunami generated by landslide. Somehow the earthquake just disappeared in the model.
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Can any one tell me how to run the comcot model for tsunami generation.
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The purpose of earthquake engineering is not to build strong and earthquake-resistant buildings that do not experience the slightest damage in rare and severe earthquakes. The cost of such structures for the vast majority of users will have no economic justification.
Instead, engineers focus on buildings that resist earthquakes' effects and do not collapse, even in severe external excitations. It is the most important goal of international standards in the seismic design of buildings.
Below I have mentioned some crucial points in reducing the seismic demand in reinforced concrete structures. If there is anything else that is not on the list, feel free to append:
1- Selecting suitable construction conditions with the desired soil type of seismic design
2. Avoid using unnecessary masses in the building
3- Using simple structural elements with minimal torsional effects
4. Avoid sudden changes in strength and stiffness in building height
5. Prevent the formation of soft-story
6. Provide sufficient lateral restraint to control drift through shear walls
7- Preventing disturbance in the lateral behavior of the structure by non-structural components
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Applied an equivalent horizontal force acting on each floor according to seismic zone.. also mode a numerical excitation in many cases shows a dynamic load factor (1.5 to 2) or higher!
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The summary can be accessed from the link below:
Please let me know whether the information that has been gathered in the summary file is informative or not.
If the summary description is not clear enough, any suggestions will be welcome.
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Thanks a lot, Dear Armin Huß
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We need to calculate moment tensor.
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Seismic Radiation From Simple Models of Earthquakes R. Madariaga
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Dear researchers
The provisions of ASCE 7-10 states that New Next Generation Attenuation Relationships (NNGAR) has been used in the process of Probabilistic Seismic Hazard Analysis (PSHA) to prepare seismic hazard maps provided in United State Geologic Survey (USGS).
Now, I want to know what is new next generation attenuation relationships and how are they different from other typical attenuation relationships such as Campbell, Douglas, Godrati, BJF, etc?
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Hello Majid
Just a few words to answer you, although I was not part of the NGA / NGA2 projects. Essentially, from a methodological viewpoint, these NGA GMPE are not different from the previous ones you quote. They may however considered are significant improvements for several reasons :
- very careful gathering of a common set of high quality strong motion data from various parts of the world, and covering an as brand as possible range of magnitude and distances, together with the corresponding Metadata regarding the source characteristics (rupture extension, fault orientation, moment magnitude, etc.), the propagation characteristics (different source-receiver distance metrics, potentiality of source- receiver configurations), and the site characteristics (the poorest though in my opinion, with only VS30, and most often only inferred and not measured - but with a clear indication of the origin of VS30 value). Personally I do no trust that much the Z1 / Z2.5 values (depth at which the S-wave velocity exceeds 1 or 2.5 km/s).
- derivation of a parallel set of numerical simulation results (with 1D codes for horizontally layered media) in order to constrain the non-linear part of the site response
- on this common data set, several groups of authors have made their own section, and developed their own a priori models for the source, path and site effects, with for some of them very sophisticated models to (try to) account for peculiar effects (directivity, rupture mechanism, NL site response, + what is ambiguously called "basin effect" corresponding indeed to deep deposits effects, etc.)
- a very careful estimation of the aleatory variability and its systematic separation in two terms ( within and between-event), with or without additional dependence on magnitude / distance / site conditions.
These NGA were developed over several years with extensive discussions between many participants, and can thus be considered as being the best State-of-the-art at the time they were developed.
Hoping to have brought useful answers, and hoping also NGA/NGA2 authors will complement and correct me !
pyb
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Dear researchers
Risk-Adjusted Maximum Considered Earthquake (MCER) Ground Motion, which considers structural collapse risk of each site in seismic hazard analyses, is used to prepare seismic hazard maps provided in United State Geologic Survey 2010 (USGS 2010).
The mentioned collapse risk are considered in MCER through risk coefficients and applying to Maximum Considered Earthquake Geometric Mean (MCEG).
How these coefficients are calculated and applied to seismic hazard maps?
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Dear Majid,
The answer to your question is very long. You will find your answer in the following papers.
- Risk-targeted versus current seismic design maps for the conterminous United States (Luco et al. 2007)
- Risk-targeted seismic design maps for mainland France (Douglas et al. 2003)
Let me know if you need more information.
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When calculating Gmax of soils by ρ*Vs^2. Does this value reduce or increase if the soil is below or above water table?
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Thank you
Najam Wani
I will check on it.
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I am doing my MSc thesis on base isolation of structures with variable curvature friction pendulum systems. I have downloaded the benchmark problem for base isolated buildings and everything is fine. However, the file which contains the nonlinear analysis algorithm of the building is in DLL format and I cannot open and edit it for my new bearing type.
My Matlab version is R2013b. I also tried some lower versions, but that did not work.
Please let me know how I can solve this problem. I really appreciate your assistance.
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Hello everyone,
I think its better if you downloaded the third generation of the benchmark building this is the link you can download, also I would mention that sometimes the Matlab version makes some problems so be careful, please such break command it does not exist in the new version of Matlab.
All the best.
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I went through FEMA-356 and FEMA-440 for target displacement and I cam across the formula as well but it wasn't helpful as i'm not able to understand it completely and I wasn't able to find all of the coefficients. It would be great if i can get a solution for that.
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You can use SeismoStruct software for the calculation target displacement based on ASCE41-17.
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Hello,
I need a small clarification on artificial and synthetic accelerograms. To my knowledge, synthetic accelerograms are those which can be derived from seismological parameters and artificial accelerograms those which can be derived from spectrum compatible. If my explanation is wrong, kindly correct me. 
Another clarification on synthetic accelerogram is, why do we multiply source, path and site terms in generating synthetic accelerogram. To my knowledge, source is related to magnitude, path is related to hypocentral distance and site is related to local geology. If my explanation is wrong, kindly provide detailed information.
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This is an interesting question.
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I am using ocean bottom seismometer (OBS) data for ambient noise H/V with a target of nearly 5 Km. To consider the water layer effect, it is important to know the theoretical concept of P-wave contribution to ambient noise H/V peaks. The frequency range I use is 0.03 to 2 Hz.
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ambient noise consist of body and surface waves and their complex interference (diffarciton, scattering, dispersion etc.). Within this scope P waves echos in the range of 'broad band' frequencies between 0.1-2 Hz. You can use therotical p wave/s wave amplitude spectrum in order to obtain h/v transfer function for deep basin (as your case-5 km)
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Hello,
I was wondering if someone could help me with following question:
I am trying to perform IDA analysis and I downloaded FEMA-P695 (22 far-field records) recommended records. the problem is the PGA of the downloaded records differ from FEMA table. In FEMA it has been written that "After this work was completed, version 7.3 of the database was released, and some ground motion parameters differ slightly in the new version, such as PGV. Even so, the variations are small and have no tangible impact on the FEMA P695 Methodology".
So how can I be sure if I'm using a correct record? Does the downloaded records need any filtering or base line correction to make them as the records from FEMA?
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You can easily verify the data for filtering or baseline correction.
1. Baseline: Integrate your time histories and check for deviations in vel-time and dis-time histories
2. Filtering: Obtain the response spectrum and check the lower and higher frequencies especially in PSV and PSD, if you find any deviations your data is not filtered.
Further, go through this paper to get ideas on data processing.
Also, I can provide you with codes (Python and Matlab) to execute basic data processing. Alternatively, you can send me your 22-time histories, and I can check and let you know the condition.
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I'm currently working on pushover analysis for multi-story structures on ETABS 17.1. The calculation time that it took was 96+ hours that too, for a building of 20 floors. I've many models to run, and some are even of 80 stories. Can someone suggest ways to reduce its calculation time for the structure?
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Dear Aakash
first, check the increments and then use Advanced SapFire Options.
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Geotechnical earthquake engineering can be defined as that subspecialty within the field of geotechnical engineering that deals with the design and construction of projects in order to resist the effects of earthquakes.
“While many cases of soil effects had been observed and reported for many years, it was not until a series of catastrophic failures, involving landslides at Anchorage, Valdez and Seward in the 1964 Alaska earthquake, and extensive liquefaction in Niigata, Japan, during the earthquake in 1964, caused geotechnical engineers to become far more aware of, and eventually engaged in understanding, these phenomena.” (I. M. Idriss, 2002)
Geotechnical Earthquake Engineering deals with the following geotechnical engineering subjects and problems::
  • Site specific seismic hazard assessment
  • Local site effects
  • Design ground motions
  • Design spectra and response spectra
  • Liquefaction
  • Seismic slope stability
  • Seismic design of retaining walls
  • Seismic design of dams
  • Soil improvement to mitigate seismic hazards
  • Seismic risk analysis
  • Foundation performance
Geotechnical Earthquake Engineering and Soil Dynamics, as well as their interface with Engineering Seismology, Geophysics and Seismology, have all made remarkable progress over the past 20 years, mainly due to the development of instrumented large scale experimental facilities, to the increase in the quantity and quality of recorded earthquake data, to the numerous well-documented case studies from recent strong earthquakes as well as enhanced computer capabilities. One of the major factors contributing to the aforementioned progress is the increasing social need for a safe urban environment, large infrastructures and essential facilities. Researchers in the fields of geotechnical engineeromg, geology, and seismology have all contributed to the developments in the area of earthquake geotechnical engineering, seismology and soil dynamics.
Large earthquakes are infrequent and unrepeatable but they can be devastating. All of these factors make it difficult to obtain the required data to study their effects by post earthquake field investigations. Instrumentation of full scale structures is expensive to maintain over the large periods of time that may elapse between major temblors, and the instrumentation may not be placed in the most scientifically useful locations. Even if engineers are lucky enough to obtain timely recordings of data from real failures, there is no guarantee that the instrumentation is providing repeatable data. In addition, scientifically educational failures from real earthquakes come at the expense of the safety of the public. Understandably, after a real earthquake, most of the interesting data is rapidly cleared away before engineers have an opportunity to adequately study the failure modes.
Centrifuge modeling is a valuable tool for studying the effects of ground shaking on critical structures without risking the safety of the public. The efficacy of alternative designs or seismic retrofitting techniques can compared in a repeatable scientific series of tests.
Geotechnical centrifuge modeling is a technique for testing physical scale models of geotechnical engineering systems such as natural and man-made slopes and earth retaining structures and building or bridge foundations.
The scale model is typically constructed in the laboratory and then loaded onto the end of the centrifuge, which is typically between 0.2 and 10 metres (0.7 and 32.8 ft) in radius. The purpose of spinning the models on the centrifuge is to increase the g-forces on the model so that stresses in the model are equal to stresses in the prototype. For example, the stress beneath a 0.1-metre-deep (0.3 ft) layer of model soil spun at a centrifugal acceleration of 50 g produces stresses equivalent to those beneath a 5-metre-deep (16 ft) prototype layer of soil in earth's gravity.
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Is there any relation between the shape of the elliptical earth and the prediction of the epicenter of earthquakes?
There are many causes of earthquakes. Tectonics plates and geodynamic conditions control the earthquake occurrence in active regions. Thus monitoring the subsurface conditions clearly help us to predict an earthquake epicenter. It is well known that the energy explodes in weak regions, fractured area or the most easiest break up part of earth.
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Earthquake or what I sometimes call geo-quake builds up becuse of stored energy that is lurking within the subsurface. The position of the epicenter, earth's surface above the focus of an earthquake where this energy lurks does not depend on the shape of the earth nether can the shape of the earth be used to predict, but it relates to the mobile plates, which create disequillibrium above, below and around the position of the lurking energy. The resuling disequilibrium causes the sudden release of energy, which is disastrous whenever it occurs. Its prediction can be achieved by assessing the seismogenic activities few hours before and few hours after the earthquake/geo-quake.
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A professor remarked that after a couple thousand kilometers from impact the length of a Rayleigh wave would be in the 200 meter range. Can anyone verify this and perhaps discuss their size when they are initially formed?
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Hi John,
I've been working on Chicxulub for the last 20 years, and this question never had come up!, with that you can imagine that I don't have a very good answer. To the best of my knowledge nobody has produced a model on this. All the models I know deal with the formation of the crater and the rheology of the target rocks.
Large meteorite impact structures on the terrestrial bodies of the Solar System contain pronounced topographic rings, which emerged from uplifted target (crustal) rocks within minutes of impact. To flow rapidly over large distances, these target rocks must have weakened drastically, but they subsequently regained sufficient strength to build and sustain topographic rings. The mechanisms of rock deformation that accomplish such extreme change in mechanical behaviour during cratering are largely unknown and have been debated for decades. In 2016 we drilled Chicxulub and it has produced a record of brittle and viscous deformation within its peak-ring rocks. In a recent Nature paper, we show how catastrophic rock weakening upon impact is followed by an increase in rock strength that culminated in the formation of the peak ring during cratering. The observations point to quasi-continuous rock flow and hence acoustic fluidization as the dominant physical process controlling initial cratering, followed by increasingly localized faulting, but no estimates of Rayleigh wave-length what so ever.
Nature volume 562, pages511–518 (2018) .
Cheers.
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Dear all,
Let me briefly go through the problem I am facing.
Currently, I have data ( of ground acceleration) obtained from the "seismic accelerograph instrument system" which was placed at the basement of the building and the plot is shown below. According to the plot, it is showing a random waveform up to a certain time and it starts decaying (damping occurs). However, it again gets another waveform (sinusoidal, as shown in the figure) after 300 sec. It looks very unusual to me. I suspect the sinusoidal part to be a building response. But I couldn't decide whether my assumption is valid or not.
So, my questions are:
  1. Is there anything (books/journals/published or unpublished thesis/lecture notes) that talks about the limitations of the time period which we are supposed to make while plotting the ground motion data?
  2. Is there any specific guidelines or any thumb-rule to determine whether the certain waveform is coming from the earthquake motion or is a building response? Normally, what I do is- I consider the random waveform as an "earthquake response" and a sinusoidal waveform as a "building response". Is it the correct way or is there another way we need to look at?
  3. My confusion arises when I saw a portion of "sinusoidal" wave before there is damping. In the figure, it is shown under the "orange" box. So, is it acceptable if I make a statement like- the presence of sinusoidal wave along with the random wave is due to the fact that the sensors recorded the both "earthquake and building response" at a time?
  4. If No, how can it be justified? If Yes, how do I correct this problem?
Thank you so much.
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There is free software which will do this, as well as adjustment and filtering, for you.
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When you look at a waveform and/or a seismograph you will see many oscillation on that. so identifying the waveform of an earthquake is a matter in signal processing. Then doing this job automatically can be more interested. So how we can do that?
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Dear Colleagues, In 2008 I have made an algorithm for prediction… With it was written the tides of Moon, Venus, and Mercury, described in my article: ‘Tényekkel igazolható a gravítáció valós oka’,… The algorithm was not published, for research and business purposes…: Venus tidal effect: ‘116 days 17 hours 45 minutes (the data is on a terrestrial scale) Mercury tidal effect: 175 Days, 23 Hours, 20 Minutes (Data on Earth Scale)’ The Vyecheslav prediction method is very good but seems he did not present all in his paper a very important phenomenon is not mentioned, perhaps similar reasons like in case of mine…
Regards, Laszlo, P.S. Today I was in Church… Exactly they read gospel was connected to the researchers who do promote such a person like Vjacheslav Nagorny Luke 10:25-37 English Standard Version (ESV) ‘The Parable of the Good Samaritan 25 And behold, a lawyer stood up to put him to the test, saying, “Teacher, what shall I do to inherit eternal life?” 26 He said to him, “What is written in the Law? How do you read it?” 27 And he answered, “You shall love the Lord your God with all your heart and with all your soul and with all your strength and with all your mind, and your neighbor as yourself.” 28 And he said to him, “You have answered correctly; do this, and you will live.” 29 But he, desiring to justify himself, said to Jesus, “And who is my neighbor?” 30 Jesus replied, “A man was going down from Jerusalem to Jericho, and he fell among robbers, who stripped him and beat him and departed, leaving him half dead. 31 Now by chance a priest was going down that road, and when he saw him he passed by on the other side. 32 So likewise a Levite, when he came to the place and saw him, passed by on the other side. 33 But a Samaritan, as he journeyed, came to where he was, and when he saw him, he had compassion. 34 He went to him and bound up his wounds, pouring on oil and wine. Then he set him on his own animal and brought him to an inn and took care of him. 35 And the next day he took out two denarii[a] and gave them to the innkeeper, saying, ‘Take care of him, and whatever more you spend, I will repay you when I come back.’ 36 Which of these three, do you think, proved to be a neighbor to the man who fell among the robbers?” 37 He said, “The one who showed him mercy.” And Jesus said to him, “You go, and do likewise.”’
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I am looking for some examples on how to start local earthquake tomography with the use of Neural network non linear optimization. I have found some previous works on the topic, But I am not much clear on how to apply the methodology on this problem. How to define the parameters? How to formulate our goal function for the tomography data. I am mainly interested in local earthquakes p and S- wave travel time data and invert it for the seismic velocity model. Is there some one working on this topic? Any help regarding my problem would be appreciated.
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Interesting idea Well worth pursuing Greetings
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When we face with a large database of continuous waveform, we have to use the necessary algorithms for extracting events automatically.
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You can check the following paper:
Akram, Jubran, and David W. Eaton. "A review and appraisal of arrival-time picking methods for downhole microseismic dataArrival-time picking methods." Geophysics 81, no. 2 (2016): KS71-KS91.
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Good morning,
I'm trying to generate synthetic seismograms for an observed seismic event.
I did compare the amplitude in the time domain, and applied the FFT for both observed and synthetic waveforms.
although all the signals are beneath 0.3Hz, I'm asking about the tolerance range in the frequency domain.
How near the frequency ranges need to be in the FFT, to tell if my two signals are similar.
Thank you in advance
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thank you very much for your quick answer, that's very helpful.
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About the HVSR method, I am interested to know:
1) The depth coverage for depicting regional structure
2) The window length, frequency range, etc. for such works.
3) Should the data be broadband or short period data would do?
4) Also wish to know if it was really possible by using data of surface seismometers.
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Thanks a lot.
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Is there a GMT script for plotting ternary diagram of Global CMT psmeca input (https://www.globalcmt.org/CMTsearch.html)? Like the one shown in the first figure.
I've been using FMC (https://josealvarezgomez.wordpress.com/2014/04/22/fmc-a-python-program-to-manage-classify-and-plot-focal-mechanism-data/) but I can't customize it such that it can also show the depth for each seismicity.
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Please take a look at the GMT manual. There are 20 examples with scripts. So you will find your answer for PSMECA and PSVELOMECA.
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Dear all, Please kindly let me know that from where I can get information about earthquakes which occurred in Kabul region, Afghanistan in the recent years?
Thanks and advance
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Hej,
Please go to the ISC catalog and download the data. Also I can refer you to an open report published by USAID and can be downloaded from NEIC at USGS website.
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Is it possible to infer the background stress tensor from the moment tensors of tensile earthquakes, which have a significant non double-couple part?
Can I apply techniques used for stress inversion of pure double-couple moment tensors to the double-couple part of my moment tensors? (i.e. using methods which assume the slip vector is within the fault plane, for example Michael (1984) method and variants of.)
If none of the above: what/how can I learn about regional stress conditions from such data?
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Thanks, Yong Zhao : this is the paper I was looking for !
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I would like to know if "2008 NYC DOT seismic design guidelines for bridges considering local site conditions" is implemented in practice or not. If anyone has some information regarding this it will be really helpful.
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Good question.. Please share me the best answer might you trust...
Regards…
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My primary goal is to find out Rayleigh wave dispersion from array of seismometer for several 100s of meters to depict shear wave velocity layers in the ocean bottom.
I am a beginner with programming.
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In my experience, python as a lot more seismic librairies such as obspy, and also a lot more seismic file read/write such as segyio librairies.
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I have acceleration data of an Earthquake in the N-S direction that I wish to impose on a structure. I have selected the domains and have applied a boundary load. But what function should I use to define the movement with the data I have? Accerleration & time.
Regards,
MM
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The soil the structure is placed on is modelled as a block, with limited depth and dimensions. The aim is to study the seismic response/waves produced by the structure to a certain depth after undergoing the prescribed movement.
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Someone told me that this wave comes from mountain winds, but the same waves were monitored by us before earthquakes. If one needs more details about the waves, I can give many examples to you.
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Jun Lv
Did you observe and responses on the infrasound system during the actual event of the earthquake?
I am so curious about the 4 day delay between the infrasound event (which certainly looks real to me). Is there some chance that this data was actually from the day of the event?......very interesting.
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I'm going to perform seismic analysis on LUSAS, FEM software. Downloaded ground motion data (accelerograms) from CESM database in the form of a text file. I have no clue how to move forward. I just know that I need two columns in a spreadsheet where one represents time, while the other one- acceleration.
Any help would be appreciated!
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Here you go, you should be able to work it out from this example file I made.
If you're smart you'll change the equation for the list under "column" so that you don't even need to split the time and acceleration columns.
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i want to understand how dominant frequency change from site to another and what controls this change? are the thickness of sediments affect on frequency and if that true what is the relation among them ?
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Dear Mohammed,
I completely agree with what others said, and would only add that nonlinear behavior of the sediment layers (for example, when peak ground velocity is larger than, say, 20 cm/s) can sometimes cause notable increase in the predominant periods i.e. decrease in the site frequency - see for example:
This increase/decrease is often a temporary one, and during a few months or years after a strong earthquake the soil gets consolidated and the frequency can go back close to the value before the earthquake.
Best regards,
Borko Bulajić
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According to FEMA P695 Appendix A
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Dear Michael,
Regarding your question I suggest you read the following published article:
Best Regards,
Prof. Snezhana Stamatovska, PhD
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The design response spectrum provides a general procedure to estimate the expected dynamic load on a structure which is expressed as a function of natural period. Thus knowing the period of the structure, design load could be calculated. It well known that the deterministic (DSHA) and probabilistic (PSHA) seismic hazard maps provide prediction of peak ground acceleration and ground motions for a specific site. As per NEHRP guidelines, design response spectrum is developed from the PSHA framework. The 2% pr 10% probability hazard level can be used for development of design response spectra which is actually satisfying a MCE level condition.
The accuracy in determination of PSA is very important in calculating the final shear load. Could you explain how to estimate such value for a given site?
How to calculate spectral acceleration (design acceleration) for the each type of site class?.
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Read section 11.4 of ASCE 07-10. It is explained there clearly.
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As you know that Mw is related to released energy for specific earthquake, so why their recorded accelerations vary for the same distance and Mw for different seismotectonic regions?
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Another effect can also play an important role when it comes to reverse fault. Indeed, the sectors on the hanging wall of the fault may exhibit greater acceleration equidistant from the epicenter than the areas on the overlapped compartment.
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It is very important to study the time-acceleration history for all seismotectonic units in all overall the world to establish new type of ground motion attenuation and for data truth.
regards
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The resources of IRIS, USGS, GEE may cater the need of required dataset.
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I would like to know type of filters or any other guidelines during collection of microtremor data and processing. I would appreciated if some one help me.
Thanks,
Ramesh Pudi
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Dear Ramesh
As claimed by Hamdullah you can use Butterworth filter. A good practice is to process microtremors data without filters. Generally the application of filters could be requested to eliminate DC component and the type and filtering band depends on also by the frequency response of your sensor and its features (electronic noise). In my experience the hygh-pass frequency should be equal to 1/2 of the resonance frequency of your sensor and low-pass frequency of comparable with the maximum frequency reproducible by your sensor. For engineering seismology HVSR applications 0.5 - 20 Hz.
Probably you already know:
-The good guideline on microtremors (acquisition and processing) of the SESAME project
- GEOPSY package (free downloadable for windows and linux http://geopsy.org/ ) for processing and inversion of the microtremors data.
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I mean all softwares to use for calculating source parameters.
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Dear Nima Dolat Abadi,
Greetings!!
Earthquake source parameters, like, Stress drop, Source Radius, Corner Frequency, Scalar Seismic Moment and Moment magnitude can be obtained by simply, Spectral model of Brune (1970) and Madariaga, (1976). SEISAN is a good freely available software for estimation of source parameters using spectral model.
Except this, source parameters can be obtained by following inversion technique of(Boatwright, (1980)
Hope it is useful for you.
all the best
With regards,
Anup Kumar Sutar
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In statistical and probabilty anslyses we are asked to compute error and uncertainty curves and values. 
Do you think there are absolute fixed error or uncertainty? Do we reach the time to say what error exist in our answers?
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Dear Dr. Raed Ahmed,
The following article may be of your help.
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As we know, there are many software for 1D site response analysis, namely SHAKE, DEEPSOIL...
Now, I need a software for 3D site response analysis. Is there any commercial software for 3D analysis of basin response to ground motion?
Can we use ANSYS or ABAQUS or PLAXIS for 3D analysis of basin response to long-period ground motion?
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hy,I would like to know how to enter the parameters of deepsoil to plaxis?
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It is well known that SAR (Synthetic Aperture Radar) interferometry is based on the SAR technology. How SAR can detect the deformation in three dimensions after earthquake happen? is it possible to measure the slip rate and fault parameters from SAR technology?
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To answer your questions you need to first make interferograms from SAR acquisitions.
So say you have interferograms from scenes captured before and after an earthquake, and you unwrap the interferogram, you essentially have a map of surface displacement caused by the earthquake (with resolution depending on how coherent pixels on the ground are). Now, that allows you to easily invert for coseismic slip distribution on a fault in 3D. But these are only static offsets. You cannot investigate the rupture process with InSAR.
Now, the more fun parts are while dealing with other quasi-static processes like interseismic and post seismic velocity fields (and possible debris flow/landslides). If you collect enough SAR scenes over a particular frame on the ground, you can create a time series of the surface velocity field. Now you can invert that data for slip rates/locking depth of faults/frictional parameters/strain rates (for afterslip/visco-elastic relaxation studies). 
The links that have been provided by some of the other responses to this thread are excellent, and should give you a more detailed description of the possibilities with SAR interferometry.
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It is clear that both systems keep the general shape of signal similar. But do they have differences in saving same signal in both systems?
digital save it in binary mood so what is the effect of sampling rate and digital recording system on signal saving?
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Digital mode are stored in zero and one, and there are more easier to handle and manipulate , while analog data are continuous with great fidelity, but very difficult to handle. Because of this,most times analog data are digitized and converted into digital data.most state of the art equipment work with digital data.
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Hello,
someone knows a program available to calculate synthetic Receiver Function?
I tried to use the Matlab toolbox FuncLab, written by Kevin C. Eagar but I think that it works only functions for RF analysis ...
Someone can help me, please?
Thanks in advance,
Leonardo
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Hi 
There are different types of tools to generate a synthetic Receiver Function. For example an iterative deconvolution process (Ligorría and Ammon,1999). It required an velocity model. Please see the following link for more details,
Best wishes
Nagaraju Kanna
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I found in a preliminary study that there is a relationship between focal depth and slip in local study in Fiji islands region,
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Dear Anup, please note that a SOLUTION being sensititive to the depth does not mean that the focal mechanism of the actual earthquake depends on the depth. If one uses waveform inversion to obtain a focal mechanism, one will get a solution that is independent of any prior determination of the depth and representative of in situ conditions.  
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I want to study the dynamic behavior of some structures that are sensitive to seismic vertical loads. All what I found is the lateral ground motions, but I couldn't find any time histories of the vertical motions/components of earthquakes. Any help will be appreciated.
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You will find the details in records Geological Survey of India and works of Quittmeyer et al 8=70s and 80s
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Strong motion data of any earthquake can give us the acceleration time history of the earthquake at the recording station, how do we calculate the ground displacement from these records? i have tried a few numerical integration techniques but am not satisfied with the values.
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@ Aadityan:
1. The two strong motion data sets belong to IIT, Roorkee and IIT, Kharagpur.
2. The EVT folder contains the original binary files of ETNA instrument.
3. Each folder contains 3 files with extension_1,_2 and _3.
4. The extension_1 is for Z-component of the accelerogram where as _2 &_3 belongs  to the horizontal components
5. In most cases Maximum PGA is observed in horizontal components of accelerogram, so you can used them for estimation of maximum displacement.
6. It is suggested to experiment with all three componets
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For the Poisson model the addition of fault sources to the smoothed seismicity raises the hazard by 50% at locations where the smoothed seismicity contributes the highest hazard and up to 100% at locations where the hazard from smoothed seismicity is low. For the strongest aperiodicity parameter (smallest α), the hazard may further increase 60%–80% or more or may decrease by as much as 20% depending on the recency of the last event on the fault that dominates the hazard at a given site.
What is the effect of Time-Dependent Source Model using Brownian passage time recurrence model on the Probabilistic Seismic Hazard?. 
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Various statistical models have been proposed for the computation of the probability
density function for earthquake recurrence, such as Gaussian, log-normal, Weibull, Gamma, and Brownian Probability Time-dependent model (BPT).
The Poisson model is standard practice for most probabilistic seismic-hazard analyses. The BPT model requires a minimum of two parameters as well as knowledge of the time of the most recent rupture. One parameter is the mean-recurrence interval, μ, and the other describes the variability of recurrence intervals and can be related to the variance of the distribution. This variability of recurrence intervals is described as the aperiodicity, α, which is related to the mean divided by the standard deviation.
The behavior of a BPT model depends strongly on the value of α. For smaller values of α, fBPT(t) is more periodic, is strongly peaked, and remains close to zero longer. For larger values, the time in which the earthquake is very unlikely, the delay or dead time, becomes shorter, and fBPT(t) becomes increasingly Poisson like. The hazard function increases with decreasing values of α and becomes Poisson like with increasing values that approach 1.0.
In general, as α decreases (periodicity increases), the deaggregation indicates that the hazard is highest near faults with the highest earthquakes rates. This effect is strongest for the long-period (1 sec) ground motions.
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In Time Dependent Model, the definition of foreshock, mainshock and aftershock is not necessary. In this model, every event is potentially triggered by all the previous events and every event can trigger subsequent events according to their relative time-space distance. What do you say about Stochastic models of earthquake clustering?
What are Stochastic models of earthquake clustering?.
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Stochastic modeling allows the computation of the expected earthquakes rate density  on a continuous space-time volume, suitable for the validation of a model with respect to others and for real time forecasts.
The significant steps made during the last decades in the physical modeling of earthquake clustering provide a tool for the refinement of these stochastic models.
Jointly with the improvement of the seismological observations, these steps appear as a progress towards the possible practical application for earthquake forecast.
In time dependent model:
The magnitude distribution is the same for all the earthquakes (Gutenberg-Richter law).
The occurrence rate density is the superposition of a time independent (poissonian)  component and that of the triggered seismic activity.
The occurrence rate of triggered events depends exponentially on the magnitude of every preceding event.
The spatial distribution of triggered events is described by an isotropic function around the epicenter of every previous event.
The temporal behavior of triggered events is described by the Omori law starting from the occurrence time of every previous event. 
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When we study the seismicity of any region we need to build a trustable caatalog. 
Could you please explain these optimal parameters of earthquake clustering?
how to build on these seismic clustered sources?
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 Each event is characterized by its location-time-magnitude parameters (x, y, z, t, m). In the following, we shall neglect the z (depth) coordinate only for sake of simplicity.
There are many optimal parameters of earthquake clustering models such as:
Failure rate fr which is a measure of the proportion of events that can be considered truly independent and constitute the spontaneous background seismicity.
K and a are constant parameters
 c and p are characteristic parameters of the time dependence process .
r is the distance from the point (xi, yi) and  is a free parameter determining the fall off of the induction effect with distance.
d and q are two other free parameters of the process
for more information about the optimal parameters of earthquake clustering can be found in the attached pdf file.
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I am interested in estimating the strain released by particular earthquakes (say x earthquake) and the approximate time required to accommodate same amount of strain in that area.
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Thank you
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I want to investigate the linear as well as non-linear responses of earthquake events, regarding this is there any other available tools such as NERA and EARA.
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Dear Nilutpal Bora
You can visit the link below, the programs were made by Prof. Nozomu Yoshida, Tohoku Gakuin University. All Softwares are free.
Here, the list of the programs:
-DYNEQ: Equivalent linear earthquake response analysis of ground
-YUSAYUSA: One dimensional seismic response analysis of ground based on effective stress 
DYNES3D: Truly nonlinear one dimensional seismic response analysis of ground with three directional input
DYNEQ is similar to SHAKE, NERA, and EERA. Detail can be found in the link.
Hope this help.
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There are different kinds of earthquake scales (Magnitude) (1) local magnitude (ML), commonly referred to as "Richter magnitude", (2) surface-wave magnitude (Ms), (3) body-wave magnitude (Mb), and (4) moment magnitude (Mw). Scales 1-3 have limited range and applicability and do not satisfactorily measure the size of the largest earthquakes. The moment magnitude (Mw) scale, based on the concept of seismic moment, is uniformly applicable to all sizes of earthquakes but is more difficult to compute than the other types. All magnitude scales should yield approximately the same value for any given earthquake, But we always find some differences.
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Dear Aadityan,
Yes you are right but we need to unify and calibrate all magnitudes in one to be used world wide. For example, i have noticed big variance in recorded acceleration despite the similar magnitudes around the world. Lately, I found that the Gorkha, Nepal Mw 7.8 2015 produced higher acceleration compared to Chile Sept. 2015 Mw 8.3.
That is why i call for urgent calibration and unifying all magnitudes. Different seismotectioc sources can produce and release different energy so why the magnitude not unified.  
Thank you for your answer
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In reliability analysis of seismic structures for determining the probability of failure, first we need to define a limit state function (LSF). LSF can be a function of some structural responses such as inter-story drift, displacement and acceleration. The LSF which contains multiple responses leads to a multiple limit state function (MLSF). which combination of structural responses is more appropriate to define MLSFs? How can we select the value of the response capacity? Is there any suggestion in codes?
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I'll attach a file, I think you should see Multiple fragility functions ( page 14) part.
 A Beginner’s Guide to Fragility, Vulnerability, and Risk
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The question is designed to triger a scientific disscussion about this important issue, correct some misconceptions concerning the whole spectrum of the area's seismicity. ( Instrumental, historical, paleo and archaeo seismicity.
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Dear Najib,
In fact, i have noticed that the historical earthquakes were not accurately matching the epicenter and the magnitude. Our historical events are not well studied. From my experience with Syrian seismicity analysis i found that the earthquake locations were mapped incorrectly and their magnitudes were risen higher than it was. Yes nobody knows exactly what happened in the past, but i am sure that the seismicity in Syria, Lebanon, Jordan and Palestine was not much strong than as it is reported by many scientists.
Based on my new published model for seismic hazard model, the expected Maximum Mmax will not be more than 7.6 in Syria for 2% probability of exceedance.
When we focus only on historical events we 100% get higher Mmax, but we should look on both instrumental and historical seismicity at same time.
I am the one who studied seismicity and prepared seimic hazard maps for syrian territory using porbabilistic approach, i found higher estimates of Mmax and earthquake hazard.
Based on this appraoch, I found that northern part of Dead Sea Fault System (syrian segment) can produce earthquake with magnitude 8 - 8.3. From my opinion, it is so high magnitude which may never happen, that is why i tried to create seismic hazard map in different way.
In the new seismic hazard model, i got surprising and promising results. Recently, i compared the occurred earthquakes of 2016 and 2017 with the pridected values. The comparison show very close matching observed and predicted results.
Obviously, we need to improve our ideas and thoughts. We can't trust the paleo and archeo seismicity alone.
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As far as I know, in seismology, we usually assume the dislocation on the fault is unidirectional thus we only see a positive part on displacement record. However, I could see not a few traces with a large negative part. Dose it mean the dislocation reverse it direction? Thanks!
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Yeah, it could be one possible reason. But this phenomenon doesn't not observed at a majority of stations. Only a potion of them have a large negative cycle. Could some other source reason or local structure have this effect?
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Previous evaluations of regional liquefaction hazards identify several geologic and hydrologic factors that influence the susceptibility of a deposit to liquefaction, including (1) the age and depositional environment of the deposit; (2) the relative consolidation of sands and silts; and (3) the local depth to ground water
Can you outline these procedures in preparation of liquefaction hazard map? If you have developed relationship in each stage stated clearly?
What are the procedure for preparation of liquefaction susceptibility map?. 
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To prepare a susceptibility map to liquefaction you need  Geological, hydrogeological and geotechnical data:  (1) You need a detailed (1/5000- 1/1000) geological map where non compacted recent geological units should appear on the map (ancient compacted deposits are not liquefiable, (2) You need a detailed geotechnical map based on in situ and laboratory tests, mainly the granulometry of the deposits (liquefiable deposits should be fine sand with less 20% of clay), (3) You need the hydrogeological map of the area (liquefaction occurs only if the table water is at depth of less than 12m). See also the following references: Youd and Perkins (1978), Youd (1998).
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I read that there is a direct relation between variation of pressure and seismic noise: high pressure correspond to an increase of noise, low pressure correspond to a decrease of noise.
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A reasonable answer is in the first page of this paper
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Actually I want to pick the coda window from the seismographs, for which I don't know the OT, But using visual inspection I can pick the P and S wave onset.
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Thnx for the reply... 
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i designed 8 story rigid frame building using static equivalent seismic load as lateral load
when i did linear time history analysis as lateral load (SE not used anymore), some of its members are overstress.
somebody told me that SE is always larger than THA and it's impossible that my members are overstress
is there possibility that THA is larger than SE in member internal forces?
i'm pretty sure that my step is based on ASCE 7-10
thank you
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It is certainly possible for time history analysis to result in a more severe response than static equivalent. You need to look at the method used to select and modify the ground motions used in the time history analysis. Compare the mean spectrum of the records (which will determine the level of response to the time history analysis) to the code-based design spectrum used for the static equivalent. You must also consider how bidirectional effects are included in each method if you are employing a 3D model as opposed to a 2D model. Recall, as well, that forces from a static equivalent analysis are reduced by the R-factor. Frankly, a linear time history analysis does not reveal much new information beyond static equivalent. Inelastic time history analysis, on the other hand, is very revealing. So I am unsure how much you gain by performing the linear THA.
If every mode of vibration were on the acceleration plateau of the spectrum (they never are) and if the response spectrum of every THA ground motion perfectly matched the target response spectrum (none of them will) then you could expect the same results from SE and linear THA.
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I am looking for accelerograms database to apply to my models. A graph including spectra acceleration and period. I can find the JPG file, but I can't download the detailed of those graphs. I've tried these websites as well.
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I have 400 recording accelerometer (accelerograms) and I do not know how to create a database
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You can use software "seizmo"  from https://github.com/g2e/seizmo/archive/master.tar.gz
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I  need paper upon sequence stratigraphy of offshore indus basin, can anyone help? 
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I need help to deconvolute Simulated Earthquake Data (created from Response Spectra  data of IS :1893-2002) Target Spectra
I am applying the input motion at the surface and recording the Time History Data at Bed rock level both in STRATA and DEEP SOIL.
But:
1) I am not sure whether to give input motion as WITHIN or OUTCROP motion.
2) If I re-convolute the Time History Data obtained at Bedrock to Surface Level then the recorded Time History at surface is not matching the Target Spectra Data.
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 Dear Ramesh, 
                          You may convert your synthetic ground motion such that it matches with bedrock motion response spectra.  You can also determine bedrock motion versus amplification curve and read the value corresponding to bedrock motion. You can check my paper titled " Obtaining the surface PGA from site response analyses based on globally recorded ground motions and matching with the codal values,". 
Abhishek 
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I am trying to fixed up error during pushover run in masonry infill model.after initial run, hinges formed in strut but suddenly it stop the analysis.I am not able to understand. Pls sombody help me.Your effort will highly appreciate. I have attached 2 model herewith. Pls give me solution. 
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Some areas of the study area did not have seismic activity, no earthquake activity area before done a more than 200 km of two-dimensional seismic profile, the seismic section has been the structure of the interpretation, How to combine the focal mechanism solution and the two - dimensional reflection seismic section structure to explain the results inversion of the regional tectonic stress field?to further explore the regional geodynamic background?
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Dear yi Yao, you might qualitatively check wether a detcted fault fits into the regional stress pattern, that means a normal fault corresponds to a largest principal sress vertically oriented and a thrust fault to a largest principal stress horizontally oriented. You might further estimate the strike of a fault which you see in your section from the direction of the principal sresses seen in the fault plane solution.
Kind regards
Rainer
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Old seismic codes provide seismic map with peak ground acceleration (PGA) values with a 10% probability of exceedance in 50 years. The new codes provide the Seismic Coefficients (Ss) & (S1). What the difference between them or what the relation between them
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You are welcome my brother.
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what could happened when seismic can see the fault but gravity can not. Seismic and gravity profile, same interval (station interval in gravity and Geophon interval in seismic as 10 meters),,,,,,,,,,any suggestions?
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Hi, dear professor Aboud , The accurate spacing for gravity survey is very effective for detect the subsurface sources. I think two or three meters spacing for gravity survey is suitable to detect the sources at depth range 6-8 meters. Spacing is only one parameter; you know the influence of accuracy of measurements, drift, accuracy of elevation, corrections, separations of residual anomaly, and contour interval of residual map. Gravity method can give good results with the accuracy in all steps from the field survey to the final interpretation stages.
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I would like to use strong motion data for site effects and estimation of predominant frequency, could anyone suggest me what is the methodology.
I am very thankful to you.
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Ramesh Hello
In this field a lot of investigations has been performed.
I attach three files.
Best,
Lev
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If a source is distant and shallow, then the incident wave to a basin will consist mainly of surface waves. When surface waves reach the basin, a part of the incident wave energy reflected back but the rest is impinging into the basin. It means the energy is decreased significantly but it still has large amplitude.
What are the causes of larger amplitude of basin-transduced surface waves?
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The cause of large amplitude of basin transduced surface waves are
1. Transmission coefficient at the basin-edge is much larger than what we expect in case of body waves.
2. Sudden drop in impedance in basin causes the amplitude amplification
3. Further, the amplitude amplification due to decrease of wavelength in basin is much larger in case of surface waves since amplitude decrease with depth is exponential in nature.
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Dear RG members
I want to know from seismic or earthquake data about the relative activity of these faults either thrusts or strike slip faults.
With best regars
IJAZ
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Hello,
We know that all three major types of faults exist in Himalayas, and all are active. Now, the question is which fault eats more food, time will tell, as more work comes out. With our current understanding about faults we know that faults survive because of deformation (stress is food for them). Just like we eat food. So generally, a big person will need more energy to survive, and thus bigger faults eat more food (via plate convergence etc). This is true of the frontal fault at the moment, which is the major active mega thrust. 
Hope this helps.
Eat healthy to remain active!!!
Regards
 Afroz
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Most great earthquakes leave in their wake stories of unusual animal behavior that preceded the main event, often by an interval long enough to be useful for warning purposes. Although much of this reported behavior has perhaps been classified as unusual only with the benefit of hindsight, a residue of convincing stories remains and it does seem possible that animals sometimes respond to certain geophysical changes associated with the approach of rock failure, that are not monitored by instruments. Anomalous animal behavior is difficult to interpret, because it may arise from various causes. But this is a defect shared with other short-term precursors of great earthquakes, so study of the subject as a possible part of an imminent danger warning scheme should not be neglected on that ground alone. Mankind`s past success in exploiting animal sensitivities, even before learning to understand them fully, encourages the hope that useful results will emerge.
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Hi
Absolutely Yes.
Animals can receive some waves or their sounds with specific  frequencies, which our hear (and other senses) can not detect them. In other hand we have not seismographs in any places. Animal's reactions will appear as unusual behavior in those places that smaller earthquake are occurring. If occurring the FORESHOCKS with frequent numbers (before main shocks) in the earthquake occurrence regime of area is common, so we can expect that the existing animal in area will react to pioneer or primary smaller shocks (which cannot be detected using far away seismographs) and show unusual behavior. In such cases we can collect at least three or more species of animals in a given place, but completely separate from others, and check their unusual behavior for all of them. If all species have an unusual behavior simultaneously, it can be an alarm of  a main shock (but not with high confidence). In many cases this procedure is unreliable and almost expensive rather than setting a seismographs in such places.
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I want to develop soil structure model in ansys apdl. And then develop response spectrum using earthquake as the dynamic loading.
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Hi, I am also learing the same thing. Here is how I have done.
/SOLU
!creating array of 18000x2 containing data of time and accln
*dim,ang,,18000,2
*CREATE,ansuitmp
*VREAD,ang(1,1),'ang','txt',' ',JIK,2,18000,, ,
(e9.3,e11.3)
*END
/INPUT,ansuitmp
*dim,awg,,18000,2
*CREATE,ansuitmp