Questions tagged [seismology]
For questions about the study of earthquakes and various seismic sources.
201 questions
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Seismic data processing software
For processing seismic data, why is Seismic Unix so important? What distinguishes it from other seismic processing software like GLOBE Claritas or Omega?
Is it argued that processing capabilities are ...
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Wave train 200 m/s meaning
I ran a 60 m line intended for surficial seismic refraction. Energization with hammer. 12 (10 hz vertical 5 m spaced) geophones and 5 shots (15 m spaced). Record length 0.5 s. Thanks to a borehole ...
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Is it possible for Mexico to have a magnitude 9 earthquake?
Everyone has heard of the Cascadia Subduction Zone and the potential threat it poses. However, I have heard nothing about The Cocos Subduction Zone, even though it caused a devastating earthquake over ...
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How to calculate seismic moment from seismograms?
I was told that
Seismic moment is determined by the observed spectral levels of the receiving waves.
But I don't quite understand what it means.
How is this done in practice? Do you need ...
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Comparing the 4th of August 1998 earthquake to the 16th of April 2016 earthquake in Ecuador
I'm doing an assignment where I'm comparing the two mentioned earthquakes, and trying to figure out which factors played a role in the amount of casualties. In the 1998 earthquake there were only ...
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Earthquake data acquisition Geosig VE-53
Is it possible to receive data from a Geosig VE-53 to a PCI data acquisition (serial port) connected to PC and without using a recorder?
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Are seismometers over the world "feeling" the small earthquakes caused by air raids and shelling on Gaza Strip?
When watching news about earthquakes, I think most people are used to hear about the Richter scale, a logarithmic scale used to measure earthquake intensity. A very strong earthquake, like the 2011 ...
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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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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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How to calculate cumulative moment magnitude?
What is the proper way to calculate cumuluative moment magnitude if I know the moment magnitude of several earthquakes?
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Seismology: What causes an earthquake? [closed]
I am doing a research on earthquakes but I cannot fully understand what causes earthquakes.
"Caused by a sudden releases of energy by the Earth's crust, causing
seismic waves which causes the ...
user6354
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Identifying continuously-recording seismic stations
I am trying to identify which stations within the NCEDC network are continuously recording ground motion, and which record only intermittently. I am using obspy's ...
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How to quantitively compare two seismic waveform data?
Our group has built an Arduino-based device with an MPU6050 to act as our seismometer for our project, with the data being displayed on Amaseis. Our proctor demands that we quantitively assess its &...
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Estimation of velocity of the wave from seismic trace
How can seismologists estimate velocity (on the different layers) of the wave propogated through the earth , only from given seismic trace(s) ?
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If deterministic wavelet is better for well ties , why do people use statistical wavelet too for wellties?
Synthetic trace generated with deterministic wavelet gives a higher correlation with real seismics.
Though it's more accurate for seismic well ties than statistical wavelet, but there is always an ...
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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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Using an accelerometer as a geophone to conduct a seismic survey
I am doing a capstone project for a sensor systems course and I would like to write a python program to acquire, process and present seismic data like that of seismic surveys. Is it possible using ...
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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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Fault representation
In most illustrations and diagrams of the types of faults, there is always something similar. I noticed that there is a side of the hanging wall and foot wall which is slanted.
We're supposed to make ...
user6354
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How well can they localize the sources of these marsquakes using only a single seismometer? Does being in the shadow zone of the core help or hinder?
Phys.org's April 23, 2022 Two largest marsquakes to date recorded from planet's far side links to The Far Side of Mars: Two Distant Marsquakes Detected by InSight which contains the image below.
...
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equivalent body force
I am currently reading "Introduction to seismology second edition, and I can't wrap my head around earthquake sources, especially equivalent body force.
What is an “equivalent body force” and how ...
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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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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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Zoeppritz equations derivation
I have been long looking for the derivations and step by step explanation of Zoeppritz matrix but either internet is full of final versions or I can’t find it...I would be very thankful if anyone can ...
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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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Source for USGS (probably not) seismic map of La Habra, California (Publication Date April 15, 1998)
I'm trying to find to original source (especially high quality version) of this conservation seismic map. I know that it probably came from USGS (or not) but looks like it out of print? I tried to ...
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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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Tasmanian earthquake patterns
While researching across the Australian Earthquake Engineering Society archive about Seismology, I came across an earthquake map of the Australian island state of Tasmania (below):
I am aware that ...
user6341
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Measuring seismic velocity with Insight lander's single seismometer
The Insight lander touched down on Mars in 2018. It deployed its seismometer and gathered 4 years of data. Recently, a paper was published which, based on Insight data combined with modeling, ...
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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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How to read and plot seismic waveform data in Ascii format using Obspy?
I wish to plot seismic waveform data using Obspy, bu they are in Ascii format. Is it possible to read and plot Ascii file using Obspy?
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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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SEG-2 vs SEG-Y file formats
I have limited experience with the different SEG file formats and I was hoping if someone could shed some light on the current preffered file formats used in software applications and for sharing ...
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How can the focal mechanism of an earthquake be determined from P-wave polarity?
I have data of P-wave polarity related to an earthquake. I tried to find the focal mechanism from the azimuth, takeoff angle, and P-wave polarity. I found that two packages, FOCMEC and HASHPY, are ...
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Necessity of demean/detrend before low/high pass filter
I am curious about the necessity of demean/detrend before low/high pass filter.
I have seismic data which had been processed by cross correlation or other things. I want to use low pass filter for the ...
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When rock cracks at tectonic plate boundaries are the number and size of cracks reflected in seismographs?
Do seismographs become more complex (waves of different frequencies superimposed on one another) for higher magnitude earthquakes where I am guessing there would be a larger variety and number of ...
user28909
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How many people will lose their lives if a big earthquake shakes Bucharest?
Bucharest becomes a huge city. Bucharest has never seen such dense population before. from 1947 to 1990 there was a communist government in Romania. 1988 Armenia earthquake with 38,000 deaths shows us ...
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What is the relationship between earthquake risk, magnitude, and distance from the epicenter?
I need a (rough) functional relationship between these three quantities. My initial hypothesis is that the risk $R$ (intended as the probability of a building damage), scales with the square root of ...
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Can the planetary alignment actually affect earthquakes? [duplicate]
We've been hearing a lot these past few days about planes alignments and how it would affect seismology. How scientifically true is that?
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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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Horizontal slowness in seismology
I am working on a seismology assignment and it starts with the fundamentals of seismology such as the wave equation, the slowness... such as the question below:
write an equation describing the ...
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What are "young thrust faults" and how does one identify them on the Moon?
The abstract of the new Nature Geoscience paper Shallow seismic activity and young thrust faults on the Moon reads:
The discovery of young thrust faults on the Moon is evidence of recent tectonic ...
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Determining the spatial orientation of a fault given ground acceleration magnitude in different directions
Accelerographs measure ground acceleration in three different components of motion: east-west, north-south, and vertically (up-down). I know that fault orientation is important here, so let's say we ...
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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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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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Need seismic data and digital well log data from the same area?
I am currently working on a project that involves the input of seismic attributes (instantaneous amplitude, instantaneous frequency etc.) to a machine learning/deep learning model (eg. A Neural ...
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Why reflection and refraction of seismic P-wave generate S-waves?
This image (taken from a 1982 paper by L. Völgyesi and M. Moser) shows that seismic S-waves are generated at reflection and refraction of P-waves. Why?
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Did the 1990 Manjil-Rudbar earthquake postpone a massive earthquake in Tehran?
In this site (published on 6 November 2001) I found the following information:
Historical data suggest there is a major earthquake in Tehran every 158 years and the last one there was in 1830.
The ...
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Finding a phase velocity and group velocity from stacked seismograph
I have seen the following images with title as "Phase vs group velocity" but never understood how this term applies in following image. how to find the phase and group velocity using R2 in ...
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Live Seismograph Plot with Grove 3-Axis Accelerometer and Seeed Studio ESP32-C3
I'm working on a hobby project to make a seismometer using a Grove 3-axis accelerometer along with a Seeed Studio ESP32-C3 to record accelerations. I am successfully getting the data to the serial ...
