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Questions tagged [seismology]

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

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4 votes
1 answer
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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 ...
Miguel 's user avatar
  • 395
0 votes
0 answers
41 views

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,...
user31690's user avatar
1 vote
0 answers
129 views

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 ...
MJ_Wales's user avatar
1 vote
0 answers
24 views

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 ...
Bishal Das's user avatar
0 votes
0 answers
6 views

Input of the relation, source and receptor files into SLB Omega

Is anyone using SLB Omega that knows how to input the source, relation and receptor files that are not using SPS format?
Xiang Jun's user avatar
4 votes
1 answer
89 views

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 ...
JeopardyTempest's user avatar
2 votes
1 answer
244 views

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 ...
ksousa's user avatar
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2 votes
1 answer
33 views

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 ...
sdg's user avatar
  • 21
0 votes
1 answer
46 views

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 ...
Snack Exchange's user avatar
1 vote
0 answers
29 views

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 ...
Joe's user avatar
  • 11
1 vote
0 answers
35 views

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 ...
user avatar
1 vote
1 answer
64 views

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 ...
user28862's user avatar
1 vote
0 answers
51 views

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 ...
AbateFaria's user avatar
4 votes
1 answer
54 views

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 ...
Miguel 's user avatar
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1 vote
0 answers
30 views

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?
Haya's user avatar
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4 votes
2 answers
1k views

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 ...
polfosol ఠ_ఠ's user avatar
8 votes
1 answer
1k views

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 ...
user avatar
2 votes
0 answers
68 views

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 &...
antuK3n's user avatar
  • 21
3 votes
2 answers
54 views

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 ...
MJ_Wales's user avatar
3 votes
1 answer
58 views

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 ...
kasyful's user avatar
  • 51
1 vote
0 answers
27 views

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) ?
Fearless_Wolf's user avatar
3 votes
2 answers
109 views

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 ...
spongpop's user avatar
2 votes
1 answer
57 views

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 ...
Fearless_Wolf's user avatar
3 votes
1 answer
107 views

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 ...
Fred's user avatar
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5 votes
1 answer
114 views

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?
Fearless_Wolf's user avatar
4 votes
0 answers
79 views

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 ...
Why On Earth's user avatar
2 votes
0 answers
22 views

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. ...
uhoh's user avatar
  • 7,092
4 votes
0 answers
35 views

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 ...
Fred's user avatar
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4 votes
0 answers
104 views

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 ...
Alessandro Jacopson's user avatar
3 votes
0 answers
40 views

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 ...
Ritwik Mandal's user avatar
1 vote
1 answer
41 views

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 ...
Trung0246's user avatar
  • 111
1 vote
0 answers
90 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 ...
Djabri Josef's user avatar
4 votes
2 answers
309 views

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 ...
Sparks's user avatar
  • 51
8 votes
1 answer
221 views

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 ...
Swike's user avatar
  • 342
3 votes
1 answer
73 views

Difference between Earthquake Seismographs

How can we tell the difference between a seismograph of a local earthquake and that of a distant earthquake?
Rim Sleimi's user avatar
2 votes
0 answers
56 views

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 ...
Rim Sleimi's user avatar
1 vote
0 answers
242 views

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 ...
Rim Sleimi's user avatar
3 votes
2 answers
66 views

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 ...
RomainL.'s user avatar
  • 133
2 votes
3 answers
125 views

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 ...
Taylor S.'s user avatar
3 votes
0 answers
66 views

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 ...
VelvetChimaera's user avatar
1 vote
1 answer
141 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 ...
simond's user avatar
  • 111
7 votes
0 answers
88 views

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 ...
rene's user avatar
  • 171
4 votes
0 answers
220 views

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 ...
Sanika Khadkikar's user avatar
1 vote
1 answer
987 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 ...
uhoh's user avatar
  • 7,092
3 votes
4 answers
383 views

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 ...
uhoh's user avatar
  • 7,092
5 votes
2 answers
795 views

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 ...
Ross Mariano's user avatar
5 votes
1 answer
145 views

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, ...
olivakyle's user avatar
1 vote
1 answer
108 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 ...
Mark Fisher's user avatar
3 votes
0 answers
179 views

Small earthquake happening every night at the exact same time

I experience this weird feeling for the last three months. Every night, at exactly 3AM I can feel small earthquake and I could not find anything on the internet related to it. Does anyone have any ...
echo6667's user avatar
1 vote
2 answers
1k views

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?
Atikul Haque Farazi's user avatar