Seismology - Science topic

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.  

One way to display multi-attributes in seismology is to use 2D colormaps. Can anyone advise how to use 2D colormap in MATLAB in the imagesc command?

If a rigid plate is bounded by two transform faults and the plate is moving, with the translatory motion of the plate will there be oscillatory motion as well? If not, why and if there is an oscillatory motion then what will be the mechanism of it?

Can rainfall affect the amount of fundamental frequency (fundamental period) and shear wave velocity profiles from the HVSR technique?

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.

Dear researchers,

Please before any of you find my question incorrect or even blame me for it, be patient until this conversation continues!

Today, for scholars, earthquake is an understandable concept, somewhat of course non unique and imprecise. If it is true, please stay with me!

This natural phenomenon varies greatly in size. Occurs at different depths of the earth's crust or lithosphere. They have different mechanisms. They can happen anywhere and anytime. Although the location of many of them is explained by plate tectonic theory, their occurrence is possible anywhere on Earth. Their magnitude on the known Richter scale can vary from small numbers (negative) to about 10. It can be happen even if be greater than 10!?!

In seismology, where the magnitude of an earthquake is proportional to the moment (Mo=µSD relation), by the same value of the shear modulus (µ) the amount of area (S) as well as the amount of displacement (D) at their very low level is ambiguous (for examples, a bulk of materials and grains size, crystal or molecule-atom scales). They are also very different in terms of origin. They originate by falling caves, erupted volcanoes and around the magma chambers, between plate boundaries (Interplate), induction such as around dam reservoirs, vary in focal depth from a few kilometers to several tens of kilometers. They also occur inside lithospheric plates (Intraplate), which may not be well understood in relation to the plate tectonics theory. In terms of duration time on waveforms (seismograms), they fluctuate between less than 10 seconds to more than 1 minute and have variation in frequencies from 0.001 up to 1000 Hz and more between 0.01 up to 100 Hz. By improvement of instruments and methods, can be sensed and detected as small amplitude as possible. If they consider as strong ground motion in earthquake engineering views because of human and financial losses (greater than 4 up to 4.5 as threshold magnitude), the task is somewhat clear. But this limitation in magnitudes does not solve the scientific problem of the source and the initiation of this phenomenon and how it was really created. Should they be considered as the propagation of elastic waves on the ground? Do they come only from the release of the elastic energy of the strain of the crust materials? As the famous scientist Reid said? Apart from breaking (fault and failure), can other phenomena produce such violent and destructive waves? As we know, Aki and Richards in their effort “Quantitative Seismology” tried to point out that seismology is the scientific study of mechanical vibrations of the Earth due to earthquakes. We also know that any small earthquake can be a pre-earthquake (foreshock) or a post-earthquake (aftershock) of a larger earthquake. Without knowing which of them, are the main earthquake (main shock), it will take a long time (hours to several days) to distinguish it. I have not yet found a powerful answer for the question. I will be very grateful if someone can satisfy me with a reasonable answer. If is not, I together with interested researchers ready to define it as a joint project for finding the proper answer.

Hello everyone.

Any one can help me with the computation of the ray parameter (p) for seismological phases?

If a code is available in Matlab, it would be most useful!

Good morning,

I tried converting seismic SAC data into SAF using Geopsy, but the results were not satisfactory. Is there any other way to do that conversion from SAC to SAF?

Thank you

Initial surface absorption test

Actually I've had done it, but the result only show tsunami generated by landslide. Somehow the earthquake just disappeared in the model.

Sylhet in Bangladeh, experienced mini seismic jolts frequently.

Sylhet is on the Assam the Indian tetronic juncture.

Induces are must to release the mounted Tremor pressure.

How quickly can this be done?

I am just curious to know, Is there a publically available catalogue of explosion occurred?

Just like the earthquake catalogue available from ISC or USGS or GCMT? Or a catalogue with the combination of both explosions and earthquake?

I working on radiation pattern to seismology ,please help me about how plot it for seismic wave at an earthquake?

I am looking for a way to increase the number of sensors in acoustic emission lab experiments. Fiber optics (DAS) is a natural candidate but the standard resolution is several meters. Is it possible to increase the resolution to cm and use the method on laboratory scale?

Good morning.

I'm trying to fix a proper velocity model for waveform inversion. I thought that if I get a good "rms" with the localisation I can start the inversion with that velocity model.

The thing is that I get a good rms (under 0.15) and an acceptable erh and erz (under 1km). The gap, the itr and the v1/v4 are also acceptable in all trials. But each time I get a different locations, far away with almost 5 km in some results.

How can we choose with certitude a proper velocity model when all trials give a good output parameter?

Could you suggest any python module that is made for dealing with statistical seismology?

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.

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.

NASA’s latest robotic geologist is starting to reveal the red planet’s pulse.

I am working in statistical seismology and we are running into a HIGHLY controversial topic. What can we say about the largest possible event (earthquake) that could happen in an area based on data? We make estimates, but what reliability do these estimates carry? There are epistemic and random uncertainties involved. There are many theoretical estimators for this quantity but many scientist doubt that they are of any practical value. I do not believe we seismologists are qualified to do more than "rambling" about the problem and I think some input from philosophers would be extremely enlightening.

I refer to papers:

Pisarenko VF (1991). Statistical evaluation of maximum possible magnitude. Izvestiya Earth Phys 27:757–763

Zöller, G. & Holschneider, M. (2016). The Maximum Possible and the Maximum Expected

Earthquake Magnitude for Production-Induced Earthquakes at the Gas Field in Groningen, The

Netherlands. Bull. Seismol. Soc. Am. 106, 2917-2921.

Zöller, G. (2017) Comment on “Estimation of Earthquake Hazard Parameters from Incomplete Data

Files. Part III. Incorporation of Uncertainty of Earthquake‐ Occurrence Model” by Andrzej

Kijko, Ansie Smit, and Markvard A. Sellevoll. Bull. Seismol. Soc. Am. 107: 1975-1978.

I have been trying to model subsurface slip with GBIS software. However, after the geodetic inversion, i don't know how to draw the subsurface slip as shown in the screenshot. can anyone please help me with it ?

the example screenshot is taken from

Jónsson, S., Zebker, H., Segall, P., & Amelung, F. C. (2002). Fault slip distribution of the 1999 Mw 7.1 Hector Mine, California, earthquake, estimated from satellite radar and GPS measurements. Bulletin of the Seismological Society of America, 92(4), 1377-1389. https://doi.org/10.1785/0120000922

Dear members of the Geophysics, Geoscience and seismology communities,

I am new in the areas of Geophysics and seismology; and I would like to get clear understanding of some technical concepts proper to these fields. Please, kindly spare few minutes of your time to answer this question so as to provide me with some tips to move on. Any suggestions would be greatly appreciated.

Thank you for your time

Best regards,

Patrice

Hello!

How can I quantify the uncertainty in the seismic wave incidence angle calculated with a single station? I have several earthquakes recorded by a single station and would like report the uncertainty to the hypocenter depths.

I will be grateful for the help.

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?

Is there a way or a simple code / software that can eliminate aftershocks of a main event with respect to time and distance?

I found on Wikipedia that the equation for primary/secondary wave speed in solids in 3D is

C_{solid,p} = sqrt((K+4/3*G)/rho)

C_{solid,s} = sqrt(G/rho)

where K is the bulk modulus, and G is the shear modulus of the elastic material, and rho is the material density.

I need to asses what would be the consequences of earthquakes over a cylindrical water tank embedded in soil (roof is at the surface of the soil).

I was wondering to do a spectral response analysis but does this makes sense if the whole structure is below the surface?

What analysis can I do over the structure to asses seismic risk? Any recommendation is appreciated!

Can anyone give me some reasons why we should use Python language programming instead of Matlab in seismology?

Hi,

I am working on Travel Time Tomography in seismology. I am looking for an algorithm for ray bending method using conjugate gradient method. If there is an existing code for the ray bending method, then it would be useful as well.

Thanks

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

Hello,

I am currently working on a software on Travel Time Tomography of refracted rays.

I have an under-determined problem and I am using sparse matrix solver like LSQR, to solve Ax = b .

Since this is an ill-posed problem, I want to apply Tikhonov regularization to the system and hence determine the "best" Tikhonov parameter, to achieve our target chi-square, after constructing the L-curve.

We are trying to minimize the cost function:

F(dx) = || Ax - b ||² + lamba² || Dx ||² + n² I dx

I am trying check if earthquakes record located around 950 km has the pP phase.

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.

Since 1988 to present began The Scientific Consensus on Climate Change. Over this period of time we have not advanced neither in climatology nor in other related sciences. Hydrology,meteorology,seismology all related sciences in the same state as 40 yeas ago.

Science is the ability to build models. Models are patterns. And the patterns somethimes are wrong. Science is the ability to be wrong.

I am working on rotational seismology, and I want to give rotational ground motion data as a input in SAP 2000, and want to check the torsional mode shapes of structure, and want to study about effects of rotational component of ground motion data, If any other software is available for this purpose then please suggest me that also.

I want a scholarship

The PGV to PGA ratio is known as a significant parameter for the damage assessment of structures under earthquake shakings. As a matter of fact, it is considered as a descriptor of the frequency contents of the seismic input motion. I am interested in understanding the physical and seismological significance of that ratio, and finally the engineering meaning, and its correlation with the structural damage.

I could not find technical treatments except empirical measurements.

Many thanks in advance for your contribution.

danilo

Geophone used in falling weight Deflectometer-to measure deflections.

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.

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!

Expensive types of gravimeters are used to detect small changes in gravity. High-precision simple pendulums, about 2 m long and using automated timing cost significantly less. In addition, they have less components and so less sources of potential errors. Also , there are issues with the springs used in gravimeters. Why, then, are the more expensive gravimeters preferred over the less expensive simple-pendulum type of gravimeter?

I'm using Seisan for Regional earthquakes. I append one event from several stations (More than 3, at list 60) and picked their phase mainly P. But I cant able to locate them. Its showing some strange error. I'm here by posting one screen shot also. But I picked one phase from at least 60 stations. Please help me.

Please suggest me how to calculate stress accumulation and strain using gps displacements for understanding the occurrence of failure (earthquakes).....

Thank you

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?

In following file you can see spectrum energy.

I am particularly interested in the ability of rammed earth walls in a simple, one-story house to resist tornado debris and tornadic winds. I am aware of the Matta et al. paper on Compressed Stabilized Earth Blocks and high winds, "Earthen Masonry Dwelling Structures for Extreme Wind Loads."

Have any studies been done on RE (wind-borne) debris resistance?

How is a continuous load path created for a house with rammed earth walls? Rebar? Geogrid? Are there articles which address this?

Thank you.

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

Hi

Rock characteristics such as porosity, density, mineralogy and mechanical properties have correlation with wave propagation. Can i achive a base method for modeling the rock with all properties?

We can make model of deep ground with seismology. Than how can optimized these methods?

Thanks

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?

The moment magnitude of the earthquake would be calculated by following formula

Moment magnitude Mw=2/3 log (Mo-9.1)

Seismic moment (Mo) = μ*S*D

My doubt is how could we get rupture length (S) and Slip of an area (D) immediately. Is there any standard model to calculate these parameters?

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?

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

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!

Seismic Image issues are very challenging in thrust fold areas, specially in highly undulated terrain. However, in recent years the Passive Seismic Tomography has emerged as a solution to the problem. I would like to know if anyone has experience and provide about case studies & papers with expert advice on how to perform the Passive Seismic Tomography in thrust fold areas for undulated terrains?

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.

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

Good morning everyone,

I should parameterize in a 3D grid my shear-wave velocity model deduced from receiver function analysis. Considering that the best velocity model which represents a discontinuity in the receiver functions is represented by a step function, how can I solve in 3D the problem of singularity (Dirac delta in mathematical terms) keeping constant (no flexibility) the discontinuity value? Someone knows or can suggest me some papers about this key point, please?

Thank you very much for your big help,

Leonardo 

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?

Some think that 25 December 2016 magnitude 7.7 earthquake might be aftershock of the 1960 M9.5 earthquake. My question is how M7.7 earthquake could be considered aftershock? Isn't it too big for aftershock? To me, there should be upper limit of the magnitude of the aftershock! 
Anyone help me to understand this phenomenon.

Best,

Mehmet

The wave diagram has been attached herewith.What is the reason of such wave?Is it noise or signal?

I have to locate the microseismic event at the site.In this regard,how after recording the waveform I can calibrate the magnitude?

We expect to see the same law acting in small scale (wells) and big scale (seismic) when dealing with fractures and corridor of fractures. Fracturing has this advantage to cross over different scales.

Can we compare orientation in seismic, using long/short wavelength curvature approach, with orientation we see in well rose diagrams ?

Dear All

I want to have the point of view from different experts given below to adopt an integrated approach.

1. Geologist

2. Engineering Geologist

3. Mining Geologist

4. Geomorphologist

5. Geographer

6. Civil Engineer

7. Mining Engineer

8. Meteorologist

9. Structural Geologist

10. Landslide Expert

11. Earthquake Geologist

12. Seismologist

Thanks for a quick response.

Regards

Ijaz

I need to design an RCC structure for a useful life of 300 years. The available Peak Ground Acceleration (PGA) value is 0.20 for Zone 2B of Pakistan. But this value is for structures with a useful design life of 50 years only. How to determine the PGA value for a structural design life of 300 years?

My goal is to obtain the spectra of earthquakes: frequent, occasional, rare and very rare. The problem is that Latin American codes just define the spectrum of an earthquake with 10% probability of exceedance in 50 years, which would correspond to rare earthquake according to VISION 2000.

So, how can I get the remaining seismic spectras: frequent, occasional and very rare? Is it correct to scale the spectrum of the rare earthquake?. Conservatively, what scale factors would you suggest?

(Please mention your source, code or etc.)

Attached seismic performance objectives proposed by VISION 2000.

Hi guys

I am performing a fault inversion for a pair of SAR SLC images. For my dinSAR map, the extents of the map is insufficient to envelop the entire seismic displacement area.

Just wondering, if I perform my inversion using such a map, what effects would it have on my results? I noted that the source modelled is accurately along the lines of existing fault boundaries. I'm am however unsure of the accuracy, especially regarding slip values.

Also, I noticed the fault inversions are iterative processes. How can I judge what should be a good result? I am processing using SARSCAPE.

Thank you

Regards

Ben

I need some databases except PEER and ISESD.

I'm looking for an earthquake record (Hachinohe 1968 , Japan) that is not in those sites.

thank you so much

Hi,

does anyone know if secondary Love waves can be generated by Rayleigh wave interaction with a sedimentary basin boundary?

I have found prior work that showcases generation of secondary Rayleigh and Love waves due to the incident of S-waves on sedimentary basin boundaries for both the observational case and numerical calculations. From a purely simplified point of view the horizontal energy of a Rayleigh wave should excite Love waves when hitting a perpendicular sedimentary boundary.

Does anyone know of any results pointing towards or against such mechanism.

Any help is greatly appreciated.

I used Wells & Coppersmith, (1994) paper (has 4417 citations) to determine the rupture width and length when the moment magnitude (Mw) was given. This paper is little bit old paper. I did not find any new paper of ground breaking idea against this paper. Do you use another approach to calculate the rupture width  formulas published by Wells & Coppersmith, (1994)? I know that the theoretical way is too complex. I am searching a simple procedure (empirical or semi empirical).

I would like to retrieve the best fitting seismic moment tensor from given pressure and tension axis orientations, even in the case of non-double couple seismic source mechanisms. I did not find such function in MoPad, any suggestion, at least for pure double-couple case ?

Figure:  for a given seismic source, I have a probabilistic representation of pressure and tension axis orientations (Left and middle plots), what is the moment tensor of the corresponding  source mechanism (right plot) ?

I want to drive (draw) a seismic fragility curve for the four damage states (Slight, Moderate, Extensive, and Complete) for an existing building. I performed a nonlinear static pushover analysis (NSP) and I got the spectral capacity curve (spectral acceleration vs spectral displacement curve). As the last step to draw the fragility cure, I need to determine the lognormal mean modal displacement and lognormal standard deviation of modal displacement values from the capacity curve. How can I do that according to FEMA (or HAZUS)? pictures for Base shear-Displacement and spectral acceleration-displacement curves are attached. I appreciate your help.

-An earthquake shook Yokadouma on September 19, 2012

-It was recorded by our station at 18h33 UTC

-We need P and S waves arrival times, the  codas, Amplitude and period of the signals and if possible the traces of the signals and location

Hello everyone.

There have been a lot of research in Theoretical Geophysics in the past like Plate boundaries,  Earth's interior, Seismology etc. But has there been any theoretical Geophysics analysis of Landslides in particular, as to how these earlier research topics are connected to Landslides.

I am interested in analyzing large earthquakes around Indonesia from 1910 until 1960. I obtained the arrival time data from ISC website. However, I need seismogram to conduct further analysis. Is there any open access seismogram data available ( the scanned image or digitized version) for this period?

Thank you

I read in many papers like this, is this because of different methodology?