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# Geomechanics - Science topic

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Questions related to Geomechanics

However, the frictional sliding or horizontal movement could also be taken into account!

Please, I am searching for master Thesis topic in Drill engineering : Geomechanic ,, Analyzing and improving technique and/ or technology of HDD for special tasks, and similar research field like Clay for Drilling Fluid.. I will be very glad if somebody could give a link or Idea on any of the above mentioned areas.

This topic is created to be a place for sharing reliable open-sources that contain quality free courses, webinars and short educational videos in the field of geotechnical engineering.

In the oil and gas industry, for technical, economic, and similar reasons, well-Log running is done from special intervals.
Therefore, to build comprehensive models for field development, we will need more information at different depths.
Today, with advances in numerical methods, especially machine learning and deep learning methods, we can use their help to eliminate these data gaps.
Of course, there are methods such as rock physics that are very practical.
But according to my results, part of which is described below. It is better to combine the rock physics method with the deep learning methods, in which case the results will be amazing.
I selected wells from the Poseidon Basin in Australia for testing and got good results.
In this study, by combining the rock physics method and deep learning (CNN + GRU), the values of density, porosity, and shear wave slowness were predicted. A comprehensive database of PEF, RHOB, LLD, GR, CGR, NPHI, DTC, DTS, and water saturation logs was prepared and used as training data for the wells.
The below figure is the result of a blind well test for Torosa well in the Poseidon Basin, Australia.
As you can see, the prediction results are very close to the measured values of shear wave slowness in this well.

I am currently focusing on 3D geomechanical modeling. And in the future, I want to extend it to a 4D model.
During my recent studies, I realized that most of the 4D geomechanical modeling that has been done has not properly updated the elastic properties such as Young's modulus, bulk modulus, Poisson ratio, etc.
If a 3D static model is extended to a dynamic model, or a two-way or one-way coupling is performed, it is necessary to consider all material behaviors in a time-dependent manner.
Please share if you have useful information in this regard or if you have a suggestion, I would be grateful if you could comment.

I want to calculate adsorption isotherms from an aqueous solution in zeolites using sorption module. Is there any way to do this or can I just calculate isotherms from molecules in gas state with the pressure variation?

Which program would be good to do this?

Petrophysical and seismic data analysis is one of the key technics for reservoir characterization and pore fluids identification. Rock physics is a link between these data and rock properties, such as porosity, lithology, and pore fluids. Quantitative interpretation and risk assessments of data and uncertainties associated with predictions need methods and multidisciplinary tools that use statistical technics and pattern recognition approaches, in addition to deterministic rock physics relations. The statistical rock physics approach is a way for quantifying the uncertainties in different steps of reservoir exploration and management. This approach applies some of the progressive statistical methods such as the Bayesian approach, Monte Carlo simulation, and Information Entropy. In addition to quantifying the associated uncertainties with predictions and evaluations, the statistical rock physics approach is a useful method to identify the most valuable information for predicting the desired properties.

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**I'm currently focusing on research, which covers topics such as geomechanics, geophysics, statistics, & numerical modeling techniques.**

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**One of my challenges in this research is a gap in log well information in some formation intervals.**

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**Given the time constraints, how can these data gaps be filled with the least amount of uncertainty?**

I'm working on a simple infiltration simulation(coupled stress and pore analysis), as far as I know, I should run the geostatic analysis as the first step.

In the geostatic analysis, I would like to set the specific saturation on the ground surface in the initial, I have been tried a lot of different methods to get a reasonable geostatic outcome that is the Sat, pore, stress is as similar as I sat in initial. But I always cannot do that. I put the information about my method. any suggestion is appreciated.

the way I calculate the value:

- Sat=G*wc/e

- pore pressure from wc by water retention curve

- stress refers to http://www-h.eng.cam.ac.uk/help/programs/fe/abaqus/doc/Geostatic6.doc

I list the different method I have a try below:

1) set predefined fields of pore pressure(elevation distribution linearly), stress(elevation distribution linearly), void ratio (constant) in initial

2) set predefined fields of pore pressure(elevation distribution linearly), void ratio (constant) in initial

3) set predefined fields of pore pressure(constant on the ground surface & bottom), void ratio (constant) in initial

4) set predefined fields of pore pressure(constant on the ground surface), void ratio (constant) in initial

5) set pore pressure(constant on the ground surface) as BC in step1(geostatic ), set predefined fields of void ratio (constant), by this way I can gain the result I want on the ground surface (but not on the bottom) after geostatic, but it always fails in the next step (transient simulation)

all BC are set: fixed x-axis in lateral, fixed y-axis or fixed y-axis & x-axis in bottom

I attached my cae file here

nowadays, the role of conventional or unconventional well log data is to know Formation evaluation. But other problems can be resolved by taking account other special data logs as an example NMR, Imagery etc..

Hello,

in my research group we would like to evaluate how the asperities of two rough planes deform when we press them together. We would like to use Abaqus, due to its advanced contact mechanics algorithms. It is not clear to us, though, how to model rough surfaces with certain statistics in Abaqus. Anyone knows any CAD software/code that could generate these models and be easily integrated with Abaqus?

Best regards,

Rafael.

Hi everyone!

How we can calculate the stress intensity factor (KI and KII) in numerical software such as FLAC, UDEC or any software except Abacus (I mean Integral J)?

There are some equations for determining KI and KII based on stress in crack tip, but it cannot be calculate the KI and KII because of teta angle in these equations. Does any relationship between KI and KII based on stress in crack tip (for inclined crack)?

Thanks in advance for answering.

Migmatites are inadequately considered as gneiss without any other distinction for civil engineering purposes. However, they are hybrid rocks generated by anatexis and composed of a mixture of metamorphic and igneous lithotypes. This feature can induce marked physical and mechanical variability in aggregates' technological properties, affecting the performance and durability of structures constructed using these aggregate rocks. In the last few years, I have been looking for articles or technical reports addressing the physical properties and mechanical behavior of migmatites' components (pelaeosome, leucosome, and melanosome), considering them individually. If you know a document with such an approach, please mention it here. I would appreciate it.

As a function of dimensions of real projects?

Hello everyone!

I'm looking for the most recent developments in analytical, numerical and experimental micromechanical modelling of mechanical and flow response of Jointed Rocks.

I would like this space to be open and free also to suggestions of materials, articles and so on.

Thanks a lot!

Augusto Borges

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?

Hello,

I would like to ask if there is anybody that have worked with an open source software OpenGeoSys to construct 3D static geomechanical model? I would very much like to hear any feedback/opinions/comments on this issue.

Best Regards,

Michal Kruszewski

Haimson and Fairhurst (1967) derived equations for the

**near-wellbore stresses**(axial*σ*, tangential_{yy}*σ*, radial_{θθ}*σ*...) around a pressurized hole in a porous, permeable "poroelastic" medium considering fluid infiltration from the borehole into the surrounding rock. Their expressions include Biot's constant,_{rr}**which depends on the Biot poroelastic coefficient,***A***.***α*_{B}Should at

**those expressions give the***α*= 1.0_{B}**same answer**as when using the standard near-wellbore stress equations for**linearly elastic media**(the Kirsch solutions modified later by Hubbert and Willis to incorporate*p*, on pages 170 and 174 in Zoback, 2010)? I was of the impression that the answer will be "yes" but the math seems to prove me wrong._{p}_{ }Based on the principles of fracture mechanics, a crack propagates when K

_{I }>= K_{IC}, i.e. stress intensity factor is larger than fracture toughness, where K_{I}=σ√(πa) for a central crack. Theoretically, as crack propagates and crack length (a) becomes larger, K_{I}increases too. Therefore, when a crack starts to grow, it never stops! However, it is not the case in many geomechanics applications in underground structures. For example, a propagating crack in a tunnel surface will stop at a distance from the tunnel wall eventually.In numerical modeling, a stress relaxation method may be used to lower the acting stress on the crack to model crack propagation more realistically. what are other efficient ways to model this phenomenon realistically? Good references are appreciated.

Thanks.

I am trying to use the swelling constitutive model in FLAC 8.00, and cannot figure out what the a1, a3, c1, and c3 swelling parameters are.They are only defined as "a soil swelling property" in the manual. I have contacted Itasca and was given some literature indicating that they are determined through triaxial testing, but have not been able to find any other literature on what these parameters specifically are or how they are derived. Does anyone have an idea of what they may be or how they are found?

can someone give me a publication about model phase2 near surface use gravity field stress ? I want to know how the deformation vector, and should I use fixed or pinned as the restraints on the surface ?

Scientists are holding a lot of experience ,and using scientific methods better than politicians and military personal ,but unfortunately they cannot hold positions,but singapore is good example,

a few times in recent years and been impressed with its wealth and modernity. I was also quite aware of its world-leading programs in mathematics education and naturally noted that one of the candidates for president was Tony Tan, who has a Ph.D. in applied mathematics. Tan won the very close election and joined the government of Prime Minister Lee Hsien Loong, who also has a degree in mathematics.

China has even more scientists in key positions in the government. President Hu Jintao was trained as a hydraulic engineer and Premier Wen Jiabao as a geomechanical engineer. In fact, eight out of the nine top government officials in China have scientific backgrounds. There is a scattering of scientist-politicians in high government positions in other countries as well. German Chancellor Angela Merkel has a doctorate in physical chemistry, so i think PH.d holders are better than bwhat is going on in America now,so how to imply this marriage of science and pollitics?

I am working on my master's thesis in geomechanics and I need a database, about 6 months or 1 year of a mine with seismicity induced by mining.

Without Laboratory experiments, is there any analytical method available to predict/model the stress path for the coal seams, which shall be very much useful in Depletion CBM operations and better long term production simulations w.r.t depeltion. I am pretty sure the conventional method for stress path determination is not going to work for coals.

Hello RG users,

The rocks are recrystallized limestones and dolomites and physically in various conditions such as in some areas the outcrop is fresh and intact, in some areas it is lightly or highly decomposed and weathered, even somewhere there are residual soils. Also, some areas contain discontinuities and some not.

Assume that I have the plain 3D geometry. I simply cannot assume that the whole area is homogeneous and has same characteristics.

My question is How can I efficiently represent such varying conditions (heterogeneity) in a 3D model based on FEM, DEM, FDEM etc. ? Is there any software capable of doing it?

Thank you!

Best Regards,

Bekir SF

In some literature, I find there is a code named BIOT2 from the following reference. Could anyone tell me how to obtain the code? Thank you.

Hsieh, P. A. (1994). Guide to BIOT2: a finite element model to simulate axisymmetric/plane-strain solid deformation and fluid flow in a linearly elastic porous medium. US Geological Survey.

Hello to all RG users,

I am currently searching for softwares to anaylze the behavior of discontinuous media such as rock masses. It would be a lot better if they are especially developed for Geotechnical Engineering applications. I am also aware that discrete element solutions such as UDEC and 3DEC would do the work. Are there any other softwares for the particular field? I am interested in Discrete Element Method (DEM) and Discontinuous Deformation Analysis (DDA) but I am also open to any other methodologies and softwares. Please keep in mind that they should be used on Geotechniques.

Thank you

Regards

Bekir SF

What is the actual nature of sand production? Shear or tensile failure? Shear bands? Erosion? or a combination of these criteria?

What is the correlation between microseismic imaging and Geomechanics?

I 'm about to start a new project which will last 6 months , the topic will be : hydrocarbons recovery optimization , using geomechanical reservoir parameters changes ?

I would like to ask you if you know any oil and gas society who would work on such a topic ?? thank you

I cannot speak to the entire discipline of

*Geophysics*, but in the**seismic world for E&P**(design, acquisition, processing, interpretation, reservoir characterization) which are for your opinion the three most important problems that strike us as important?Let me share some issues:

Rock Physics and seismic elastic inversion?

Geomechanics and anisotropy for unconventional reservoir?

Discrimination between lithology and fluid content?

Thank you very much for your answers, I will try to put a synthesis with your best knowlegde and point of view.

Mario E. Sigismondi

I am currently investigating the load-carrying mechanism of a driven pile (hollow bar) and trying to install strain gauge on the pile for measurement of stress distribution. I have tried to install the strain gauges on both outer and inner surface of the pile with sealant and protective tape on but they all fail due to the large driving force applying on the pile. Most of the gauges broke at the lead wire connections. Is there a way to install the gauges that can withstand large driving force?

Regards, Philip

Dear fellow researchers

In rock mechanics there are several methods to up-scale lab results to the field results (especially for Young's modulus) as it most of the times make a significant difference in analysis of tunnels, caverns, etc. However, in petroleum geomechanics the structure in question is a wellbore with a very small diameter (mostly less than 10 in.). I was wondering how much scale effect may be inflict in such a problem? Since the opening is almost as the size of the plugged core samples, is there any significant difference between lab mechanical properties and in-situ properties?

For instance, Rayhani and El Naggar (2008) posited that the said distance ought to be greater than five times of the superstructure width.

Rayhani, M. H., & El Naggar, M. H. (2008). Numerical modeling of seismic response of rigid foundation on soft soil.

*International Journal of Geomechanics*,*8*(6), 336-346.Have you got any other references, covering the question of interest?

I am trying to make a geomechanical simulation in Ansys 17. I need to change the element type to CPT 216. So far I have inputed

et, matid, 216

r,matid,5000000 !(for 5 MPa pore pressure)

in the APDL command script.

I know this is incorrect, but I have two general questions:

1. Do I need to do this for every node? I have a 5m x 5m x 1m slab of shale I want to simulate.

2. What am I missing in my code? Do I need more parameters?

Any advice or help is greatly appreciated.

Experience in using the method of discrete elements in solving problems of geomechanics.

Any idea/suggestion about using molecular dynamics simulation about transport and geomechanical fate of proppants?

Hi

We're going to calculate the shear mode of rock specimen.

Thanks

I am wondering how to tie the seismic data and well log information to build a geomechanic model...

Hello,

Is it possible to compare classification results of GSI, RMR, and Q-system for flysch grounds?

Or, it's better to work just with GSI classification?

Thanks.

Rafik.

Hello all.

According to the AFTES guide, schisitosity is a type of discontinuity.

However, this schisitosity may not be an interruption of the continuity of the rock matrix but rather a rearrangement of minerals (with certainly a weak zone where detachment is easier).

For the geomechanical classification of a shist (eg. RMR), what is the rating to take for spacing discontinuities?

it will always be the lowest rating?

Rock mechanics

Tunnel engineering

Engineering geology

are the GSI estimation formulas from (RMR) and (Q-system) still valid? (GSI = RMRbasic-5) and (GSI = 9log [(RQD / Jn) (Jr / Ja)] + 44)

are there new formulas.

Hello all.

The identification of the squeezing potential of the ground is mainly based on the rock UCS, and on the height of overburden.

Is there a direct relationship between the deformation modulus of rocks and the potential of squeezing?

Thanks.

Please, I am searching for master Thesis topic in petroleum engineering(Drilling) : Geomechanic ,, wellbore stability in deviated and horizontal well,,optimum orientation well path , and similar research field.. I will be very glad if somebody could give a link or Idea on any of the above mentioned areas.

I am researching on hydro-mechanical processes in deeper fractured crystalline (basement) rocks up to 2000 m depth below surface. For my research I compile hydraulic data (permeability and hydraulic conductivity data) from different sources (e.g. hydraulic/pneumatic packer testing, tracer testing). Especially data from 1000-2000 m below surface and from schistose rocks (from upper greenschist metamorphic facies/contact metamorphic equivalent and higher) are sparse. I have already a compilation of data stemming from publications of radioactive waste research in US, Canada and Europe. If you have references to other published data sets please let me know.

a question

Someone has experience in the duration of split sets over time

With water with neutral pH or without water.

Using splitsets in tasks that last 10 years.

or slightly alkaline?

Dear all,

I am modeling a slope with discontinuities in UDEC.

According to UDEC manual, the vertical stresses are usually equal to

*gρz.*However, when I assign the insitu stress by this way, some joints will slip or separate when the model is brought to an equilibrated state.I am wondering if researchers could suggest me about this case.

Thank you in advance!

**Title 1:**High speed train X2000 on soft organic clay - measurements in Sweden. Proceeds of the 12th European conference on soil mechanics and geotechnical engineering

Title 2: High speed lines on soft ground: soil behaviour. laboratory test results. Ledsgard and Peppared at Vaskusrbanan

Kindly share them or forward them to 15197832@sun.ac.za

Your assistance will be highly appreciated

Suppose in a basin we have a dam and we want to naturalize the flow at the outlet of the basin. What are the ways for naturalization of streamflow, so that the dam effect can be neglected. I have a long series of streamflow record prior to the dam construction.

Hello everyone, I'm trying to experimentally study the effect of Cd movement through a heterogenous soil column simulating a pumping aquifer. Can anyone help me in how we can find experimentally, the link between one dimensional flow and solute movement ?

I am reporting on shale unconfined compressive strength (UCS) values for a petroleum audience. Some laboratory data I received from CoreLabs and TerraTek report in psi, however I have seen academic and professional publications reporting in MPa and psi. Have you seen a trend of preferred units for the various industries for UCS and/or Young's Modulus?

Generally, we know that EDEM and PFC3d have perform the same functionality in DEM.

However, after a long search I have found that most of railway ballast modelling that are used in academic research have been modeled by PFC3d.

However, I like the functionality and ease of EDEM even there are limited academic researches about railway ballast used EDEM.

What are the key differences between PFC3D and EDEM for Discrete Element modelling for ballast railway track applications? Which one is more appropriate to be used in my research area?

I am a graduate student of civil engineering. I have recently done my undergraduate thesis on "Numerical analysis of swelling behavior of Shale with PLAXIS Software". Therefore I am just interested to know about your current research work.

this happens before and after i insert the water

I want to study the effect of spatial variability of rock mass properties on the stope stability using FLAC. I therefore need to write a FISH functions that will spatially assign the rock material properties into the FLAC model.

Assume that we drill a vertical well, but when we get a survey of borehole trajectory we find that there is some deviated angle and azimuth. Some people say that, because of the weight of an anticline core, the but does as a plummet and get a deviation to crest of anticline. But I want to know the effects of stresses and rock strength independently from bed layering. Is it true that a well makes a deviation to low stress concentration?

Currently I'm working on a COMSOL project on geomechanics and that have two physics models of solid mechanics. And i am changing geometry by making holes in horizontal direction (representing Tunnel Excavation).

Here my problem is to change the geometry in each step, and the values in the previous step(i.e.t0-1) also must be used in another new step (t0) and so on.

If anyone could give me some suggestions on this, it would be highly appreciated!! Thanks in advance.

I try to correlate the stress regimes from the world stress map with hydraulic measurements. I am able to connect the single sites of hydraulic measurements to sites of stress estimations but what puzzles me is up to which distance this correlation makes sense (horizontally and vertically)? I know stress regimes may change dramatically within short distances and therefore I doubt there is an universal answer but maybe you can provide some thumb rules? Thank you!

Hi everyone!

The safety factor is a factor for checking the results. How much is the safety factor for different slopes based on different standards or guidelines such as UIC, British standard, and etc.? Is it different for rock slope or soil slope in different conditions such as static or dynamic conditions (ODE/MDE/MCE)? Should it be considered based on special projects like high speed railway or other projects?

Thanks in advance for sharing your experience!

Hi everyone!

Some researchers believe that in the depth (more than 15 meters) there is no liquefaction potential for sand layers. Is it true? Is there any example and reference? And is there any sensitive for surface structures in this area (I mean a sand layer is located in the depth more than 15 meters) if an earthquake happen? Do you introduce new relationship for checking the liquefaction potential and its potential relationship with depth?

Thanks in advance for sharing your experience!

Metamorphic minerals such as garnet, andalusite, sillimanite, kyanite and staurolite

Dear colleagues,

I am currently working on a multi-material arbitrary Lagrangian-Eulerian (ALE) method for applications in geomechanics and geotechnical engineering. In most multi-material ALE methods, a typical calculational cycle is divided into (i) a Lagrangian step where the motions of the material and the computational mesh coincide, and (ii) a remap step in which the mesh is rezoned (relaxed) and the variables are transferred to the rezoned mesh; see reviews in [1, 2]. In multi-material Eulerian formulations the mesh after the Lagrangian step is moved to its original configuration, so that it appears to be fixed throughout the calculation.

Depending on how the mesh is rezoned, so-called multi-material elements may arise which contain a mixture of materials separated by interfaces. The mixture is treated as an effective single-phase material on the element level by using some kind of mixing rules (mixture theory). Free surfaces are modeled by multi-material elements containing "void material" with (nearly) zero stiffness and mass density. Interfaces resp. free surfaces are typically reconstructed and propagated element by element using Volume of Fluid (VOF) or related techniques.

Almost all ALE or Eulerian methods use explicit time integration schemes in both the Lagrangian and remap steps. The range of application of such "hydrocodes" is therefore limited to dynamic problems having a relatively short-time duration. Reference [3] is the only one I know which deals with implicit integration in the Lagrangian step. Can somebody provide other references? Thanks in advance.

Regards,

Daniel

[1] D. J. Benson. Computational methods in Lagrangian and Eulerian hydrocodes. Computer Methods in Applied Mechanics and Engineering, 99:235-394, 1992

[2] H. U. Mair. Review: Hydrocodes for structural response to underwater explosions. Shock and Vibration, 6:81-96, 1999.

[3] D. J. Benson. An implicit multi-material Eulerian formulation. International Journal for Numerical Methods in Engineering, 48:475-499, 2000

[ Studying rock samples with different patterns and structure]

I read the ASTM D 1883. In this Code only the duration of the soaking is proposed. There are other papers in which a controlled temperature for this test is introduced. Is there any idea regarding the temperature and chemical composition of the water. Is is a distilled water or tap water or anything else?

Is the technique of geosynthetic-encased stone columns in soft clay applicable really? And is it possible to make geosynthetic around a stone column technically?

As we all know, rock mass is weaker than intact rock, so how can we modify the strength parameter of intact rock to match the strength parameter of rock mass in continuum numerical modelling?

Please consider a specimen that is compacted in Optimum Moisture Content (OMC). I want to increase the moisture in this specimen so that the moisture distribute throughout of the specimen uniformly. For example, imagine that the OMC is equal to 10% and I want to increase the amount of moisture in this specimen after compaction to 15%

A normal-sense shear zone has a true thickness of 7km. It dips 30º on average. The longitudinal strain-rate is on the order of 10

^{-11}s-1. The duration of extensional movement is around 2-3 m.y.What may be the total slip along the dip of the shear zone?

Hi All,

I want to derive an analytical solution of a boundary value problem for wellbore plugging. Let us assume, a soil mass is placed in a cylindrical container with full of fluid (water or oil) and fluid will enter to the soil mass. Therefore, soil mass will swell.

Field Problem:

Hydraulic fracture or well bore plugging using bentonite pellet. Fracture initiation process, fluid enter to the rock mass (soil mass) and they swell Or in plugging bentonite pellet absorb fluid and swell.

I used following references, but still not clear how to cope up the solution.

*Detournay, E. and A. H.-D. Cheng (1993). Fundamentals of Poroelasticity. Comprehensive Rock Engineering: Principles, Practice and Projects, Vol. II, Analysis and Design Method. C. Fairhurst, Pergamon Press: 113-171.**Detournay, E. and A. H.-D. Cheng (1988). "Poroelastic Responses of a Borehole in a Non-hydrostatic Stress Field." International Journal of Rock Mechanics and Mining Sciences & Geomechanics 25(3): 171-182.**Charlez, P. A. (1991). Thermoporoelastoplasticity General Theory and Application. Rock Mechanics, Volume 1 - Theoretical Fundamentals, Editions Technip: 183-238.*

It is noted that I know geotechnical or geomechancis issue but in Petroleum or Minning totally new. At present, I am not considering thermal diffusion part. Most probably the problem is related to the coupled diffusion-deformation process. Any co-operation will be appreciable.

Regards,

Mohammad Nurul Islam

We collected gravity data on a slope in Avcılar where near the North Anatolian Fault Zone (NAFZ) . We think that, we can study or collected gravity data on any slope (there is a slope stability problem) and gravity value are affected by on that. However, we worry that why does the gravity change on the same measurement point in 7 days. The increasing value is approximately 38 mgal near to (NAFZ) in Turkey? The measurements were conducted with the CG-5 Scientrex device. The stress is increasing sharlpy or not? We asked it to you.? For the earhtquake prediction, Is these increasing is normal or not?

Sincerly.

Dr. Savas KARABULUT (Istanbul University)

Would you describe to me, in a short way, the different stages of this relationship by using FEM