Skip to main content
13 votes
Accepted

How is known that the Earth core is solid?

This is a good observation. The reason we can measure S-wave (transverse) propagation in the inner core is because P-waves can set up S-waves and vice versa. When an S-wave hits the mantle-outer core ...
bon's user avatar
  • 2,211
12 votes

Carbonate reef not horizontal in seismic section?

This phenomenom is called velocity pull-up. The seismic waves that reflected off the top of Layer 2 beneath the carbonate layer have also travelled through the carbonate. Because carbonate (at least ...
stevej's user avatar
  • 1,044
8 votes
Accepted

SEGD and SEGY recorded data

SEG-D is a specialized format, while SEG-Y is a general-purpose format. In general, SEG-D is intended for field recordings of seismic data, and SEG-Y is intended for 'seismic data exchange'. Having ...
Matt Hall's user avatar
  • 11k
8 votes
Accepted

2018 Swan Islands earthquake tsunami

This is the centroid moment tensor published by the USGS as of 01/10/18 (it will likely be updated in the future). As you can see this was an almost pure strike-slip mechanism on a near vertical plane....
bon's user avatar
  • 2,211
8 votes
Accepted

Do planetary alignments affect Earth's seismic activity?

It's easy to make prediction of earthquakes in Turkey/Türkiye, it's in one of the most active seismic zones on the planet. The February 2023 earthquake had a magnitude of 7.8, with aftershocks of ...
Fred's user avatar
  • 24.7k
7 votes
Accepted

Using accelerometer as a seismograph

The magnitude of an earthquake is related to the total energy released, therefore to estimate it from a seismogram you need to know the distance to the source. In the case of the Richter scale for ...
Camilo Rada's user avatar
  • 17.7k
7 votes
Accepted

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

SEG-Y files are a general purpose archival format. So they can be "anything". 2D seismic, 3D seismic, raw, processed, unstacked or even derivatives (seismic attributes). How to get information about ...
Way of the Geophysicist's user avatar
6 votes
Accepted

How to interpret seismic interferometry data?

It is a differential InSAR image that shows wrapped phase in radians which is a measure of the change in range (or distance) between the ground surface and a (more or less) fixed point in space from ...
stali's user avatar
  • 2,381
6 votes
Accepted

What is the purpose of wavelet extraction from the seismic trace?

We're usually not interested in the wavelet per se, but we need to know it in order to understand how the seismic trace relates to geological properties we are interested in. According to the so-...
Matt Hall's user avatar
  • 11k
6 votes
Accepted

Are seismometers over the world "feeling" the small earthquakes caused by air raids and shelling on Gaza Strip?

Bomb explosions are detectable as seismic events, but the energy falls off with distance, so for quakes of less than magnitude 3 you'd have to be with a few 10s of kilometers, depending on your ...
jeffronicus's user avatar
  • 3,487
5 votes
Accepted

Prompt gravity signal induced by the 2011 Tohoku-Oki earthquake - could this really be useful for warnings?

If you have a sufficient number of sensors, e.g., land-based or ocean-bottom seismometers, in the vicinity of where strong earthquakes typically happen, then it will take a few seconds for seismic ...
Wolfgang Bangerth's user avatar
5 votes

Relationship between tides and earthquakes

I don't find Ide et al's recent paper to be very convincing. They only studied three earthquakes - hardly a statistically representative sample. There are millions of earthquakes on record, and ...
Gordon Stanger's user avatar
5 votes

What causes ringing effect when using corner filter?

Filtering is always a convolution of the signal. What you are doing in the frequency domain will also be manifested in the time domain. A sharp edge in frequency domain will create a long convolution ...
user2821's user avatar
  • 5,946
4 votes

Good Open source alternatives to SeisImager & RES2DINV?

Actually, there are plenty of alternative DC Inversion software; I hate using res2dinv; unfortunately it's relatively easy to get into. I would have much preferred ZondRes2D for it's user experience. ...
Coastal's user avatar
  • 146
4 votes
Accepted

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

You need to see the InSAR data. E.g., see this image which is based on radar data acquired by ESA's Sentinel-1A satellite. For straight faults the pattern is not this complicated. Using such ...
stali's user avatar
  • 2,381
4 votes

Is the centre of Italy still at risk of earthquakes?

The Italian Civil Defense's map of earthquake risk zones shows Rieti in at best Zone 2, "Medium-high seismicity, quite strong earthquakes possible", and near or in Zone 1, "High or catastrophic ...
cphlewis's user avatar
  • 521
4 votes
Accepted

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

Accelerometers, preferably triaxial (i.e., those that record horizontal and vertical motion). Beyond that your question is indeed a bit too open-ended. Some use many cheap MEMS (http://onlinelibrary....
Erik's user avatar
  • 1,999
4 votes
Accepted

Would climate change result in an increase in seismic activities?

Dilation of the Earth's surface due to atmospheric temperature changes will be negligible due to the amount of temperature increase. Stronger precipitation will not directly lead to an increase in ...
Fred's user avatar
  • 24.7k
4 votes

Does the Moon affect earthquakes?

Actually, yes, but indirectly Well, the tidal forces produced by the Moon's gravity are not enough to distort the Earth's crust enough to produce any significant displacements of the crust, and ...
Alastor's user avatar
  • 261
3 votes

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

The intent with this (very, very cool) device seems to simply be to improve hazard assessment and mitigation by providing higher resolution motion data. It reminds me of tiltmeters used on volcanoes. ...
user7939's user avatar
3 votes
Accepted

seismic wave detection standing at the epicenter

A person would not detect much else than the surface waves (Love and Rayleigh waves). The later body waves phases are of very low amplitude and are only detected by a sensitive seismometer. Also, at a ...
user2821's user avatar
  • 5,946
3 votes

How do seismic charges help to investigate the subsurface?

Explosives are just one way we can produce seismic waves in the ground. By placing geophones on the surface, which measure the rate of change of displacement of the surface, we can actually guess ...
Jay's user avatar
  • 61
3 votes
Accepted

How does moveout correction work in seismic reflection profiling?

The offset is measured in meters, but the depth is still measured in time. The extra distance the wave have traveled to a longer offset is therefor also seen as an increased time in the CMP-gather (...
user2821's user avatar
  • 5,946
3 votes

Global scale seismology experiments / observations disproving flat earth conspiracy?

As you rightly say, seismicity is one geological proof of an almost spherical planet, but surely it is far easier to prove your case by satellite data, such as scenes from http://weather.msfc.nasa.gov/...
Gordon Stanger's user avatar
3 votes

How can we determine the size and composition of Earth's inner core?

The previous answers are correct in that geophysics and crust-mantle samples are the main tools for sorting out the composition of the core. In addition, don't forget that meteorites are the solid '...
Gordon Stanger's user avatar
3 votes
Accepted

Detecting seismic waves using Software Defined Radio

I hope I understand your question right, I think there are some confusion about frequency range and wave-types. Seismic waves are acceleration of matter that transfer kinetic energy from a seismic ...
user2821's user avatar
  • 5,946
3 votes

Seismometer records ground displacement or acceleration

A geophone (type of seismometer) contains a coil of wire, wrapped on a mass, surrounded by a magnet. As the Earth moves we assume the mass stays still due to inertia and this changing magnetic field ...
Jay's user avatar
  • 61
3 votes
Accepted

Lights associated with earthquakes?

I am not too much into the subject, but it is a curious phenomenon indeed. There is a recent publication in Scientific Reports (Enomoto et al., 2017) where a group of scientists performed some lab ...
ValeVolc's user avatar
3 votes

Acoustic impedance in geophysical context

This concept actually comes from the electrical. They define the impedance as $Z=\frac{V}{I}$. Where V is potential difference/ voltage and I is current. In acoustics, a similar expression can be ...
Amartya's user avatar
  • 347

Only top scored, non community-wiki answers of a minimum length are eligible