# Questions tagged [seismology]

For questions about the study of earthquakes and various seismic sources.

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153 views

### 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 ...
1 vote
275 views

### 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 ...
• 141
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### Can an igneous rock have a Vp of less than 1000 m/s and need blasting to excavate?

I have run a 60 m refraction seismic line on a mountain summit. The environment was noisy (wind would be the principal agent) and quite difficult to pick first arrivals. It resulted in 800 m/s. A ...
155 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 ...
112 views

### 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 ...
1k views

### Where can I download historical sesimic data in CSV/Excel format for processing in R?

I'm not familiar with these kinds of data sets but I'm looking for some data for a project I'm working on. Essentially I would like multiple time series of seismic data from different stations over ...
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1 vote
228 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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1 vote
155 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 ...
1 vote
88 views

### 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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### How does multiple layer seismic reflection work? How do we distinguish arrivals from different layers and their velocities?

Whenever we are investigating multiple layer interfaces in a seismic reflection survey the root-mean-squared velocity is often employed to deduce travel time to a certain n-th layer and also to deduce ...
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1k views

### Travel Times for Seismic Wave Types - Why reflected t-x plot curves

I do not understand how the reflected wave in a seismic survey has a steepening slope (slows down) Please bear with me as I lay out my thoughts because I feel like I can grasp all of this except this ...
• 303
1 vote
107 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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1 vote
92 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 ...
• 796
1 vote
25 views

### 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 ...
• 183
135 views

### Rayleigh waves generation

Good day, I do not fully understand the physical mechanism of formation of Rayleigh waves at the free surface. While their derivation is quite clear and obey free-boundary conditions, it is not clear ...
241 views

### How sensitive are typical seismometers?

NASA recently landed a seismometer on Mars, with what sounds an impressive detection ability, with press reports gushing it is "able to detect vibrations smaller than a hydrogen atom." A more ...
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Is it possible for an earthquake to generate such a design in a sand pendulum during an earthquake? I saw an article online describing the story of a shop owner finding one of his pendulums had ...
67 views

### Difference between landslide waves and earth quake waves

I am new to this field, recently started working on landslide monitoring mainly in signal processing part. I have the following questions? 1.Will each land slide and every vibration have p wave, s ...
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1 vote
462 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 ...
• 141
207 views

### Using acoustics to measure the composition, density, and hardness of layers

I am an engineering student at Alfred University and some fellow classmates and I are doing a competition, but one of the tasks we need to complete is autonomously measuring the composition, density, ...
• 51
115 views

### Could glacial melt alter plate tectonic movement?

Let's say some event caused runaway glacial melt, and removed half of the ice currently locked away in specific areas of the planet. Would the significant weight changes on various plates and fault ...
214 views

### Why do major earthquakes keep happening in Lombok recently?

So I've been following the situation in Lombok, Indonesia from both online news and friends on the ground. One thing that I can't seem to figure out is why there are so many earthquakes over an ...
42 views

### statistical methods for analysis of stability tailored for multiple short time series

I am a graduate student of Ecology working on a species diversity problem and am not much educated in time series methods. i have searched 3 general time-series books and could not find a clue on how ...
1 vote
83 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 ...
1 vote
81 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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166 views

### 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 ...
358 views

### Open source well information viewer

I am in the middle of a hobbyist experiment and would like suggestions on an open source HTML viewer for mud loggging, FMIs, lithology and seismic. I have used INT before but for this project I would ...
290 views

### Which type of seismic sensors usually used in Earthquake Early Warning?

As I'm a newbie in seismology and related area, I would like to know which type of seismic sensors usually used in earthquake early warning systems?
1k views

### What is the relationship between raw seismic data, CMP Stacking, NMO & Machine Learning

I recently joined a geophysics project to assist with some of their machine learning modeling but am trying to gather the domain knowledge required to participate. Something I don't quite understand ...
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395 views

### 2018 Swan Islands earthquake tsunami

How come the strike-slip 7.6 M earthquake, occurring January 9th, 2018, produced no tsunami? Has there ever been any produced in this region?
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### Acoustic impedance in geophysical context

What is the intuition behind acoustic impedance? Yes, I know that it is the opposition to a seismic wave travelling in the medium. But why it is defined as density × velocity? The velocity of a ...
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1 vote
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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### 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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### Lights associated with earthquakes?

According to the New Madrid, Missouri web site, during the 1811-1812 earthquakes there were reports of lights coming from the ground due to quartz crystals being squeezed. They call this phenomena “...
9k views

### SEGD and SEGY recorded data

What is the difference between a segd recorded data and a segy recorded data and can we convert from segd to segy and vice versa?
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1 vote
368 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?
381 views

### How can I calculate the sensitivity of a seismometer?

I would like to know if a specific seismometer can measure 1 micron/sec velocity. I have a few specs from the datasheet but I'm not a seismologist and am trying to figure out how to relate the specs ...
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117 views

### Is the centre of Italy still at risk of earthquakes?

I am working on a project which involves taking over a business based in Italy. It is a small village situated near Rieti (Sabina Hills) called Casperia and I am wondering if it is on a fault line? Is ...
508 views

### What causes ringing effect when using corner filter?

I used the corner filter (band pass) with this frequency values (8,10,45,50). I get ringing effect on the data. my questions are: what is the name of this effect and the cause? should be removed and ...
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1k views

### Seismometer records ground displacement or acceleration

I believe Seismometers record ground displacement. However, I have also read in certain articles that this can be ground displacement or acceleration depending on the frequency of the seismometer. ...
710 views

### 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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### How to interpret seismic interferometry data?

Here is a screenshot of coseismic interferometry measurements of the 2015 Nepal earthquake. What does it mean? The star is the epicenter of the earthquake. The screenshot was taken from the UNOSAT ...
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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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256 views

### What (if anything) can be learned from accurately recording tilt motion during seismic events?

The Rotational Motions in Seismology (ROMY) instrument is a giant laser gyroscope used to generate extremely precise 3D rotation measurements of planet Earth. However at the end of the video below ...
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131 views

### Earth's inner core has an inner core inside itself. Are there three inner cores?

The Seeker.com article Earth's Inner Core Has Its Own Inner Core states that researchers at University of Illinois and Nanjing University in China have made a bizarre discovery. They've found that ...
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### seismic wave detection standing at the epicenter

If a person is to stand at the epicenter of an earthquake. Is it true that he would not detect P-waves nor S-waves echoing off the mantle core boundary? Since if P-wave that enter perpendicularly ...
4k views

### How do seismic charges help to investigate the subsurface?

In the film Kong: Skull Island, scientists investigate an island's structure by dropping explosive charges from helicopters: Source: YouTube trailer In reality, geophysicists do something similar ...
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5k views

### Using accelerometer as a seismograph

I'm using ADXL345 accelerometer with Raspberry Pi to build a seismograph. I've successfully hooked it up and can plot the accelerometer data in three axis. Is there any way to express these data in ...
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I have been trying to evaluate the analytical solution for a wave travelling in a homogeneous, infinite media. For a given source $S(t)$, the wave-field can be calculated at a distance $r$, for a ...