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

The simple answer is that you can't drill to 50 km depth. The deepest holes ever drilled were to a little more than 12 km, one is named the Kola Superdeep Borehole in Russia, which was a scientific ...
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26 votes
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Is it true that earthquakes are not felt in a cave?

Ground motion results due to passage of elastic waves. Now there are different kinds of waves, e.g., P waves, S waves, surface waves, etc. Most of the shaking (and therefore damage) is caused by ...
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  • 2,361
26 votes

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

10 seconds is a worthwhile warning time. The Japanese use it to switch off compressors on gas lines (or open release valves on them), emergency break bullet trains, and in particular shut down nuclear ...
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17 votes

Is it true that earthquakes are not felt in a cave?

There are three main types of waves produced during an earthquake: P, S, and L waves, which stands for Primary, Secondary, and Love. (There was a mnemonic I read many years ago that went P=pressure, S=...
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  • 2,137
16 votes

P wave to S wave conversion

P and S waves are fundamentally different, when it comes to properties of the wave. An example might be that P waves can travel through fluids while S waves cannot. However, when it comes down to wave ...
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15 votes

Is it true that earthquakes are not felt in a cave?

Googling leads to a very old document: EFFECTS OF AN EARTHQUAKE IN A MINE AT TOMBSTONE, ARIZONA stating that in many cases, mine workers did not notice earthquakes which were felt above ground. A ...
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  • 994
14 votes

Why are there more intense earthquakes in Iran than in Iraq?

These two images probably explain it best: This is a map from the US Geological Survey Earthquake Hazards Program, which shows all recorded large earthquakes in the region from 1900 to March 2012. ...
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  • 5,337
14 votes

Why Vp/Vs and not Vs/Vp?

After quite a bit of conversation on Twitter, I think it's arbitrary. Tradition is probably the prevailing reason. It would be interesting to go back through the literature to see who first used it. ...
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13 votes
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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 ...
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  • 2,211
12 votes

Are Richter-magnitude 10 earthquakes possible?

Well the dinosaur-killing asteroid that struck the Yucatan peninsula in the gulf of Mexico (65 million years ago!) generated a seismic shock or earthquake that went around the world and registered ...
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12 votes
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Interpretation of a seismogram (three components)

Yes, the vertical component of the seismogram looks different than the horizontal components. There are surface seismic waves (Love waves or Q-waves) that are horizontally-polarized. The ground motion ...
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  • 3,780
12 votes

What do the derivative or the integral of amplitude of a seismogram mean?

This is a very simple answer, and it depends on the what the seismometer is measuring. I'm assuming you mean the time derviative/intdegral $\frac\partial{\partial{}t}$ or $\int{dt}$ Most ...
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  • 6,376
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 ...
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  • 1,044
11 votes
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Successful Earthquake predictions

The Haicheng Earthquake is the only successful evacuation of a devastating earthquakes. It's notable that the Chinese scientists thought they had figured out ot predict earthquakes, but have ...
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  • 6,376
10 votes

How accurately can explosions be triangulated from the IRIS seismogram data?

David Salzberg and Margret Marshall suggest that using green receiver functions (which might make more sense given how we determine the difference between explosions and earthquakes) can locate a ...
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  • 6,376
10 votes

Are Richter-magnitude 10 earthquakes possible?

It's definitely possible, though not very likely as mentioned above. An unusually long subduction zone, like the Peru-Chile Trench, Aleutian Trench, or Japan-Kamchatka Trench would have to rupture in ...
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10 votes
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Can earthquakes contribute to Antarctic ice loss?

There are two ways in which earthquakes could affect the Antarctic ice sheet, either by occurring on the Antarctic continent or by occurring elsewhere and sending tsunami-type waves towards the ice ...
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10 votes

Is there a correlation between hot springs and earthquakes?

Yes, there is a correlation. In other words: places with hot springs are more likely to experience earthquakes than places without hot springs. The relationship is scale-dependent in time and space (...
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10 votes
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Why do most seismic inversion methods ignore high frequencies?

Because those frequencies are not present in the seismic data. Here's an example with some typical numbers: Seismic sample interval: 4 ms Therefore Nyquist is 0.5 $\times$ 1/0.004 = 125 Hz Usually ...
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9 votes

Regarding velocity of P/S-waves

That is not a silly question! And your intuition is correct: As you bury and compact a sedimentary rock, its porosity will decrease, so its density increases. But we also see that its velocity tends ...
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  • 947
8 votes

Probability distribution of fault throw displacement and height limiting mechanisms

This is a very interesting question, and one that many people have explored. It's also a very complex question, as geology is inherently complex. A complete answer would probably require you attending ...
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  • 1,044
8 votes
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Why does seismic activity shed light on the inner core rigidity?

The question that Azzie Rogers linked to: How can we determine the size and composition of Earth's inner core? Does answer the theory part of the question, but I will extrapolate a little more to ...
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  • 6,376
8 votes
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Temporal Resolution of Seismic data

In seismic data analysis we have to distinguish between vertical (temporal) and horizontal resolution. The (First) Fresnelzone is linked to the vertical resolution and defines the area in which the ...
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8 votes

Is earthquake prediction possible?

See it is relatively easy to predict where a large earthquake might occur, assuming you have been monitoring deformation for a long enough period, more or less equal to the average inter-seismic ...
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  • 2,361
8 votes

Do other terrestrial planets have "earthquakes"?

For terminology, "Earth"quakes might be replaced with "seismic activity" since earthquakes are by definition restricted to the Earth. Technically speaking the other terrestrial planets in our solar ...
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8 votes

About Earthquakes and their properties

The presence or absence of a large number of massive buildings has no bearing on where and when earthquakes occurs, or their magnitudes; particularly along major fault systems such as the San Andreas ...
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8 votes
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Is there a correlation between hot springs and earthquakes?

Hot springs usually exist in volcanic regions or in areas where there are extensive (normal) faults. The water circulates through the fault zones (basically damaged zones with high permeability) ...
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  • 2,361
8 votes
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Where does the 2015 Nepal earthquake rank amongst earthquakes since 1900?

About 80th. I counted the earthquakes of each magnitude on the List of deadly earthquakes... article. If the Nepal earthquake is about M7.8, then it's in the range 69th to 86th on that list: Note ...
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