Questions tagged [seismic]

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210 views

How do we know the speed of S-waves (shear waves) in the Earth's inner core? Has this been measured?

Wikipedia's Seismic wave includes the plot below of the speed of S and P waves as a function of depth in the Earth. In the region of the outer core the speed of S-waves or shear waves is shown to be ...
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1answer
374 views

Quality control in Seismic Acquisition - How much data is required?

When it comes to land or marine acquisition (oil exploration, for instance), I can see from literature that quality control (QC) is performed during the survey to ensure that the seismic traces ...
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1answer
97 views

Seismic Reflectivity and Fractal (Random) Behavior

*One of the fundamental assumptions of the convolutional model (and subsequently a lot of deconvolution methods) is that reflectivity is a purely random (or "white") process. Overall, the only ...
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1answer
53 views

Recent high seismic activity in Europe

It seems that Europe and the Mediterranean Sea have had high seismic activity in last six months. Major events which I remember are: 2020 Aegean Sea earthquake, magnitude of 7.0 Mww 29 December 2020:...
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31 views

Seismic wavefield theory: velocity anisotropy

Does the reciprocity principle hold true in an anisotropic subsurface environment?
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1answer
55 views

Love-Wave Propagation

Love-waves cannot exist in a half-space. Layering must be present and there also must be accompanied impedance contrasts associated with the layering. Because layering naturally induces seismic ...
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2answers
1k views

Seismic dispersion: What does it really mean and what causes it?

Body waves (to some extent) and especially surface waves show dispersive characteristics during propagation. In Dr. Christopher Liner's book [Elements of Seismic Dispersion (2012)], this phenomenon is ...
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1answer
73 views

What does 'reghosted' mean in a seismic cube label?

I came across to a seismic volume labeled as reghosted. In my understanding, a seismic survey is deghosted as part of a processing step. Then I wonder why one would like to reghosted the data? Is ...
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1answer
53 views

What would be the phase shift and polarity of a seismic wave upon reflection

What would be the phase shift and polarity of a seismic wave a) when it hit the free surface b)when the free surface reflection goes down and hit a reflector and returned to the receiver placed on the ...
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1answer
52 views

Q factor estimation from VSP

in seismic data processing there is a step of calculating the absorption represented By Q value which is Q factor , how we can estimate it from VSP ! thank you.
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1answer
121 views

wave speed is smaller than both horizontal wave speed and vertical wave speed?

I am new to GIS and just get the idea of slowness. I can understand why people need the slowness in GIS rather than just the reciprocal of velocity. However, I feel the definition of slowness is weird ...
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1answer
107 views

reverse time migration for wave equation PDE using SBP-SAT

I'm stuck implementing a reverse time migration technique, the PDE(partial differential equation) being implemented is an acoustic wave equation, The numerical method being used is a FD(finite ...
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1answer
83 views

Spectral Whitening, Seismic Interferometry

What is the role of spectral whitening in the processing step done before cross-correlations in seismic interferometry?
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1answer
136 views

What is seismic stretch in geophysical method?

What is seismic stretch in geophysical method ?
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1k views

Can large earthquakes happen few times at same place(in days)

I want to know if large earthquakes can happen twice in the same place? I live in Istanbul/Turkey. In Canakkale/Turkey too many earthquakes happen for days! I know it is normal for this region but 4.8 ...
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0answers
34 views

What are the boundary conditions for Navier's Equations of motion in seismic?

Navier's equations of motion in seismic have 3 solutions, according to how it is resolved (boundary conditions): for Vp (compression waves) for Vs (shear waves) for Vr (Rayleigh waves) I know the ...
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0answers
20 views

Quality control in Seismic Acquisition - shot offset shift

I have a problem with seismic data where the minimum offset of the shot is not centered at the nearest receiver, this shift can be for 3 traces 2 or one and maybe more in the two sides !! So is there ...
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18 views

Conversion of SEG-Y relative to MSL

I am working on the conversion of CSF file from SonarWiz into SEG-Y data. However, it comes back always related to the Sensor depth/altitude and never to the MSL. I have tried changing the bytes from ...
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0answers
54 views

How does uplift lead to onlapping?

I read in a paper that: Interpretation of 2-D seismic lines shows the lower to middle Patchawarra Formation onlapping onto paleostructural highs at approximately 270 Ma and again at 273 Ma, ...
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0answers
62 views

Finding out actual dip and dip direction of refractor

We have two traveltive curves for first arrivals (direct and refracted) from a dipping refractor in the forward and reverse directions along a profile line. my question is: Is there a logical way (non-...
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62 views

Seismology - PPV / VDV from geophone waveform data

I'm using an inexpensive seismometer to try and measure the effects of local HGV traffic on buildings. The device is connected to a Raspberry PI that has a Cirrus Logic Audio Card. The signal is fed ...
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52 views

Interpretation of horizon display

I am currently working on a project that involves using seismic attributes as input parameters in a neural network for estimation of porosity and permeability for a reservoir. Now, I need to correlate ...
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0answers
59 views

Problem in identification of seismic event?

I have taken the following synthetic seismogram, generated using Marmousi model, from the Madagascar website. I could not understand the origin of linear events (present in shot3 after 2 sec) and ...
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0answers
180 views

Does seismic anisotropy follow stratigraphy?

This question is in the context of velocity model building for reflection seismic imaging (between 0km and 10km in a sedimentary basin). This is really a rock physics question disguised as an imaging ...
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0answers
357 views

Effects of Mexican Earthquake in San Andreas Fault Line

Could the recent 8.1 Magnitude Earthquake at the Cocos and Nazca plates off the Mexican coast have a knock on effect to the Pacific and Juan de Fuca Plates further north at the San Andreas Fault Line?
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126 views

Linear vs nonlinear seismic inversion

I am using the MATLAB script BLIMP (Ferguson and Margrave, 1995) to invert SH-wave data for shear-impedance. Is this inversion scheme a linear or non-linear process? There are certainly non-linear ...
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0answers
50 views

Shear-Waves and Stress

-I study the near-surface via seismic reflection surveying with shear-waves. I know that effective stress strongly influences the velocity behavior of any body wave in the near-surface (5 - 50 m). My ...
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1answer
61 views

Where can I find broadband seismic reflection data?

or what type of companies should I contact to ask for the data? This data would be produced from Seismic Vibroseis survey trucks which are mostly used to locate oil and gas. I doubt most oil and gas ...
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1answer
93 views

Hydrophone/geophone sensor sensitivity - noise versus signal

Today, a student asked this question, and I was unable to answer it in a way that was understandable and accurate - even for myself. For seismic data acquisition projects, how are sensors able to '...
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1answer
39 views

Is it reasonable to approximate the swinging building (base of the building) during an earthquake to a simple harmonic motion?

I am thinking of making a model of swinging building during earthquake and study the methods to minimize the swinging. So does it even makes sense to approximate the swinging buildings (the base of ...
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1answer
83 views

Near-Surface Investigations: FWI vs. MASW

MASW is a common processing method for civil/geotechnical and even for oil/gas exploration (usually weathering static corrections) applications. In my experience, it seems to work well for most ...
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1answer
103 views

DC component: Seismic inversion

Multiple papers (for example, Limitations on impedance inversion of band-limited reflection data Gosh[2000]) and textbooks covering seismic inversion mention a necessary component of any seismic ...
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35 views

Are there specific layers in the subsurface that come before gas or oil?

Currently, I've started working on a geophysics project. More specifically, I'm trying to find gas and oil reservoirs in SEGY files using deep learning. I've been reading about seismic reflection ...
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28 views

Preconditions for stacking

Some of the requisite for stacking is that the noise and amplitudes need to be uncorrelated. Can someone explain to me why? Also is there a drawback for stacking?
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66 views

Theorist speculate about dozens of loud atmospheric booms across globe

Theorist speculate on the dozens of loud atmospheric booms across globe. Has any recognized institutions offered a plausible explanation as of now?

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