Questions tagged [seismology]

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

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355 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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1answer
71 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 ...
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1answer
341 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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5answers
4k views

Why aren't seismic stations installed very deep underground so as to pre-warn from earthquakes?

The velocity of p-waves emanating from earthquakes is in the range of 5-8 km/s (link)--let's assume it is 5 km/s. The earthquake depth is up to hundreds of kms deep underground (link)--let's assume it ...
10
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1answer
233 views

Carbonate reef not horizontal in seismic section?

Carbonate reefs usually appear as homogeneous bodies surrounded by sediment layers in seismic reflection data, but in the figure below the high amplitude reflection from the top of sediment (layer 2 ...
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1answer
345 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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0answers
68 views

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 ...
7
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1answer
287 views

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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0answers
116 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 ...
6
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1answer
686 views

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 ...
6
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1answer
222 views

Cross-line fold of a towed-streamer survey

On page 29 of the book 3D Seismic Survey Design by Gijs O. Vermeer, Vermeer says that the equation for a maximum fold in a 3D survey is the following: $M = M_i \times M_c$ where $M_i$ is the inline ...
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2answers
2k 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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1answer
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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2answers
762 views

Good Open source alternatives to SeisImager & RES2DINV?

Are there any good open source (Linux) alternatives of SeisImager which includes Pickwin and Plotrefa and file formats are .sg2? Same question for ...
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1answer
67 views

Is “seismic energy released” a regionalized variable and can be analyzed using geostatistics?

In geostatistics, we can assess and analyze regionalized variables. Tectonic stresses releases in seismically active regions by occurring earthquakes. We can calculate and estimate the seismic energy ...
6
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1answer
566 views

How does moveout correction work in seismic reflection profiling?

When you take a seismic reflection profile you take multiple shots and then stack them together around a common midpoint. Due to the extra distance travelled by the wide angle shots there is a moveout ...
7
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2answers
157 views

How do they know the 2016 Kaikoura (NZ) Earthquake was 'complex', involved six different faults?

The BBC news article New Zealand quake: The geological impact of a 'complex' tremor says: The powerful earthquakes which hit New Zealand were some of the most complex ever recorded, say scientists. ...
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1answer
751 views

Where does the 2015 Nepal earthquake rank amongst earthquakes since 1900?

Wikipedia provides a list of deadly earthquakes since 1900. Where would the April 2015 Nepal earthquake (magnitude currently estimated as 7.8 or 8.1) rank in this list, in terms of magnitude?
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126 views

How to find instrumental response for a seismic station

I received seismic data for which I would like to remove the instrumental response. The only information I have is that they were recorded on a Trillium broadband seismometer with a cutoff period of ...
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2answers
252 views

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 ...
11
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2answers
829 views

Discrete Slant Stack on seismic data

In the formula for slant stacking (tau-p transform) a substitution t=tau+d/v is made. If we consider the substitution as a vector equation then how can vector d/v ...
5
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1answer
82 views

Is the concept of seismogenic zone still relevant after the 2011 Japan earthquake?

The concept of subduction seismogenic zone, where megathrust seisms occur in a layer between an upper and a lower limit is well documented in the 1990/early 2000 literature : Some example : Pacheco,...
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1answer
136 views

Relationship between tides and earthquakes

Ide et al. (2016) suggest that earthquakes (especially those of high magnitudes) are more probable during periods of high tidal stress (during full and new moons). While they show a comprehensive ...
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3answers
16k views

Can large earthquakes happen twice/thrice at the same place within a short timeframe

I want to know if large earthquakes can happen twice in the same region? The reason is that the recent earthquake in Nepal was followed by many after shocks of considerable magnitude. I wanted to ...
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2answers
125 views

Earthquakes in Oklahoma influenced by Humans?

I'm currently living in Oklahoma, and there has been an abnormal amount of earthquakes lately, by abnormal I mean more then 5 in a day(not sure if that's normal or not).. I've also been told that in ...
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1answer
276 views

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 ...
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1answer
951 views

Detecting seismic waves using Software Defined Radio

I understand about physic and waves, but I am a totally rookie in this topic. I was wondering which are the typical frequency ranges of the S-waves, P-waves and surface waves. My idea would be to ...
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1answer
161 views

Are the other causes of an earthquake (e.g. volcanic eruptions) the cause of the “sudden slip” which is the main cause of an earthquake?

I am to deliver an informative speech about earthquakes in class. However, I was not the first to talk about earthquakes and his discussion of the cause of earthquakes is different from mine. He ...
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2answers
2k views

Why can Thomsen's parameter $\epsilon$ be negative in VTI media?

I just got several well log curves, some of which are Thomsen's parameters. They are a result of interpretation of Sonic Scanner tool measurements (Schlumberger). Negative epsilon values appear quite ...
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1answer
566 views

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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1answer
1k views

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 ...
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0answers
52 views

Seismic attenuation in mixed gas/water

Imagine I set off an airgun in the ocean and I measure the far-field signature. Then I do the same thing shortly after introducing tiny gas bubbles into the water, and mixing them well. Are there ...
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2answers
42k views

How do seismologists locate the epicenter and focus of an earthquake?

I know the focus of an earthquake is where the earthquake originated from, but what I could never figure out is, how to scientists find out where exactly the focus (and epicenter) are located?
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1answer
560 views

How is known that the Earth core is solid?

As I know, the Earth core is solid. This is known, because it conducts also transverse waves, while liquids conduct only longitudinal waves. But, how was it found? The inner core is in the outer core,...
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1answer
260 views

Can a 99.9% probability of an M≥ 5 earthquake within a 3-year period be verified?

Paper: Potential for a large earthquake near Los Angeles inferred from the 2014 La Habra earthquake (2015) Obviously there has been much discussion on the viability of earthquake prediction. This ...
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1answer
136 views

Regarding velocity of P/S-waves

I feel like I am missing something blindingly simple, but I am curious about something. We are given the velocity of a P-wave as $v_{p} = \sqrt{(K+\frac{4}{3}μ)/ρ}$. So I am to understand ...
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0answers
33 views

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?
12
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1answer
459 views

Where and how can seismic data for earthquakes and volcanoes be downloaded?

I need it in this format. I went to USGS and IRIS websites but couldn't understand the downloading procedure
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2answers
421 views

What determines the spectrum of high and low frequency waves emitted by an earthquake?

Does the shape of the fault that the earthquake originated from determine its ratio of high frequency to low frequency waves? What about shallow-fault vs deep subduction zone earthquakes?
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2answers
647 views

Is it possible to prevent high magnitude earthquakes by induced earthquakes?

As we know, earthquakes can be induced by human activities. Can we induce earthquakes around faults regularly so that the energy releases regularly, and hence prevent high magnitude earthquakes by ...
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1answer
609 views

Are volcanoes formed from earthquakes?

I know that some earthquakes are caused by volcanoes and that some earthquakes can trigger volcanic eruptions close to where the earthquake is. But what if a great earthquake(8.0 or above) occurs and ...
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4answers
2k views

What would a replacement for SEGY look like?

I have been having a miserable time this week reading SEGY files. This is data from the largest seismic acquisition company in the world whose client is the 7th largest oil company in the world. So if ...
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1answer
139 views

Which component in a 3-component Sp receiver function is the actual Sp RF?

In a 3-component Sp RF I have the green's function in P,SV, and SH. The actual component to the RF that shows the Sp conversion (the one always published in the literature), which would represent as a ...
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1answer
190 views

Should RTM amplitudes (pre- and post-stack) be related to rock physics properties?

There is as huge uplift in the image quality near and under salt bodies (e.g. the Middle Miocene of the deepwater Gulf of Mexico) by using reverse time migration or RTM. We can now make accurate ...
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1answer
400 views

How are the ZNE, ZRT and LQT coordinate systems defined?

I'm confused about the direction of Z (upward or downward?), R (outward or toward the source?) and T.
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1answer
249 views

Will another big earthquake hit Kathmandu?

Recently, we got the news that the western part of Nepal may be hit by a larger earthquake than that of April 25, because it did release all of its energy. During the earthquake, only the eastern part ...
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8answers
3k views

Is earthquake prediction possible?

After the Tohoku and East Coast quakes, I skimmed over several books discussing the validity of earthquake prediction as a discipline, yet found no significant breakthroughs. What should change in our ...
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2answers
1k views

What would change if our earth lacks mountains?

I just asked myself what is the role of the mountains on our planet earth? Well there's a well known role for the climate and weather. But is there a kind of physical or geological role? What would ...
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2answers
346 views

How strong can a glacial icequake get?

While researching Antarctic geology, I came across the term 'icequake' in the abstract to the article Seismicity within a propagating ice shelf rift: The relationship between icequake locations and ...
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1answer
125 views

Evidence of a seismic trigger of the Storegga Slide ~8.2ka

The Storegga Slide was a catastrophic underwater landslide that occurred off the coast of Norway about 8,200 years ago. This YouTube clip shows simulations that indicate that this slide resulted in ...