Questions tagged [seismology]
For questions about the study of earthquakes and various seismic sources.
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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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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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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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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 ...
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What is the pitch and roll in a tiltmeter sensor?
I wonder if you could help me to understand what the pitch and roll mean for an tiltmeter sensor? I have tiltmeter data and I don´t understand at all how it works. If you can recommend literature on ...
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Zoeppritz equations
I have a question regarding zoeppritz equations. The equations from Telford are as follwoing:
When trying to put in a matrix form, by converting amplitudes to reflection and transmission coefficients,...
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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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What's the strongest earthquake we currently can miss observing on Earth?
Reading jeffronicus' answer about how seismic stations record bomb explosions, particularly the reminder that the intensity of earthquakes drops by distance, made me start wondering what scale of ...
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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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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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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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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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Where could I get waveform data on low-frequency earthquakes, very low-frequency earthquakes, volcanic tremor and non-volcanic earthquakes?
I am a marine geology masters student and I am writing my thesis on slow earthquakes. I will include graphs of the most common types of earthquakes:
Low-frequency earthquakes
Very low-frequency ...
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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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Do planetary alignments affect Earth's seismic activity?
There is a widely circulated tweet by Frank Hoogerbeets where it seems he has predicted Turkey's earthquake a few days before. The tweet says:
Sooner or later there will be a ~M 7.5 #earthquake in ...
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Does the Moon affect earthquakes?
Does the Moon, through factors like its location (if it is at an apsis i.e closest point or furthest point in its orbit) or some changes in density, affect earthquakes on the Earth?
Earthquakes are a ...
user27902
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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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Where can I access public sonic well-log data?
I'm doing some research and I'm in need of some well-log data from a sonic tool. I'm specifically looking for a multi-receiver tool with 6 or more receivers if possible.
I've been able to find a lot ...
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Is there any free indexed journal that Geoscience students can publish?
I am planning to publish a paper related in Geoscience/Geophysics/Seismology within scope of Machine Learning/AI in particular. Is there any Journal that provide free article publishing for ...
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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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Seismic velocity relations
I do understand why the seismic velocity decreases with temperature and increases with pressure, but I am not really familiar with the relationship between the velocity with Poisson's ratio. I ...
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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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The longest interval between earthquake main shock & after shock
On August 21, 2022, the Western Australian town of Cadoux experienced a magnitude 4.4 earthquake. According to the report of the incident, that earthquake might be an aftershock of a magnitude 6.1 ...
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What is the purpose of wavelet extraction from the seismic trace?
I would love to know what exactly we can do with the extracted wavelet. What kind of information extracted wavelet can contain?
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Why on Earth are there observatories on the active Mauna Loa?
Near the summit of Mauna Loa there are two observatories. Mauna Loa is an active volcano that is being watched, so why did they build observatories up there instead of building them on the dormant and ...
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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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Seismicity associated with post glacial rebound
Allied to the question: Why is relative sea-level falling in Hudson Bay?, where the surviving answers mention post glacial rebound.
Is seismicity associated with post glacial rebound and if so what is ...
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Book recommendation on waves
I am looking for a book about waves in the context of Earth Science, the two main topics I have in mind are ocean waves and seismic waves.
Explanations in a book like Understanding earth1 is too ...
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Why core refracted phases like SKS polarise vertically when P to S conversion happens in the Core-Mantle boundary?
While working on investigation of seismic anisotropy I came to know that core refracted phases like SKS or SKKS polarise vertically when P to S conversion happens in the Core-Mantle boundary. Why is ...
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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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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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Does the Earth produces measurable gravity waves?
Does the Earth exhibit measurable gravity waves? Note: I'm not asking about gravitational waves.
Some recent experiments looking at low-frequency (3$\times 10^{-5}$Hz) accelerometer data are showing ...
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Where can I find an anisotropic PREM-like model for Earth's interior?
So, I just discovered PREM (the Preliminary reference Earth model) which models the density distribution of matter inside the Earth to any depth.
The PREM is very convenient but since it only depends ...
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Difference between Earthquake Seismographs
How can we tell the difference between a seismograph of a local earthquake and that of a distant earthquake?
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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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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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Would climate change result in an increase in seismic activities?
Would climate change result in an increase in seismic activities?
I can see two potential forces acting:
Temperature dilation of the Earth's surface.
A change in the distribution of water mass, fewer ...
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Is an Earthquake Large Enough to Cripple the Entire West Coast of North America Possible?
I have an idea for a novel I want to turn into a reality, and I'm starting some research first to make my book at least plausible in very specific conditions. The main aspect of the story would be ...
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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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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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What condition(s) need to be met to be able to determine the hypocenter of a microseism?
Today, this XKCD popped up in a chatroom:
comic CC BY-NC 2.5 linked to the source
User Rob mentioned that (as usual with XKCD) this is based on the findings in a research paper.
In Source location of ...
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Beam forming FK analysis of a seismic wave
So after reading alot of literature on source localization, I found out that FK analysis is one of the most widely used methods to determine source location without explicitly calculating the ...
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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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Do we know anything about the nature of Earth's core that hasn't come from magnetic or seismic measurements?
There is much known about Earth's core from painstaking analysis of seismic data, and from detailed magnetic field maps and trends over time.
Are there any other measurements that have contributed to ...
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Performing time-frequency analysis (FTAN)
I am trying to do ambient noise tomography and I am quite confused on how to perform time-frequency analysis (FTAN) as shown in figure 13b and 13d of this paper by Bensen et al.. I am using Python and ...
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What are today's methods in calculating the Local Magnitude of earthquakes?
I'm no expert and barely have any idea about this. But I want to know if the methods in calculating the Local Magnitude can only be done manually? I mean manually by first reading a seismograph, ...
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