Questions tagged [geophysics]

Geophysics is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment.

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4
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1answer
419 views

Why is fluid pressure in a fractured rock reservoir only dependent on hydrostatic pressure?

Why does lithostatic pressure not play a role? (or does it?)
4
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1answer
212 views

Gravitational Anomaly of a subsurface body

How does the gravitational anomaly measured at the Earth's surface and produced by a subsurface body depend on its depth and on the density contrast of the body relative to its surroundings?
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2answers
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How viscous is the Earth's mantle?

I'm posting here to get some more expert information based on this question. If the Earth were to stop rotating, removing the centrifugal force causing the equatorial bulge, how long would it take ...
12
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1answer
908 views

What's the distance between the center of mass and geometrical center of Earth (CM-CF offset)?

I asked the same question on Physics StackExchange site. I now know that there are several types of "center" and I can tell, I'm interested in the CM-CF offset (CM = geocenter, CF = center of figure). ...
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1answer
636 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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0answers
93 views

SeismicUnix - Finite Difference Migration [closed]

I'm trying to apply sumigfd on simple.su data which is used in the John Stockwell course in geophysical image processing - in the Migration chapter on page 85. I have not had any success because the ...
9
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3answers
580 views

How bad is geo-engineering?

It is just curiosity that forced me to ask this question. At some point in time, if we can't control global $\sf{CO_2}$ emissions, temperature will increase until a tipping point and it will be a ...
8
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1answer
140 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 ...
10
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1answer
4k views

Why is the South Pole colder than the North Pole?

This question popped into my head because I am designing a fictional world map, and I was wondering what factors influence the amount of ice at poles. I want to know why there is much more ice ...
6
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1answer
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Compute direction of gravity vector

As I understand to compute vector of gravity not saficient to compute normal to elipsoid, but we need to computer normal to geoid (by definition geoid is a surface to which the force of gravity is ...
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4answers
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Does gravity differ from place to place on Earth

Does a particular object have the same weight on every part of Earth or does it vary?
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3answers
267 views

How probable is is that earth magnetic field will change 180 degrees at once?

Today the Earth's magnetic field is moving a little bit. But is there going to be a point where the field suddenly radically changes direction? If so what is the cause of that? If not, then is the ...
2
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1answer
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Why are oceans so deep?

Some areas of oceans are about 11 km deep. Is it because continental plates were moving away because of troughs in the middle from where new rock is formed? If so, why did it become deep? If not, what ...
4
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1answer
189 views

Is there a differential angular rotation on Earth?

I asked a question about solar day difference between two latitudes on the same longitude here on the Earth surface. The answer was clear due to constant angular rotation time is the same. Tangential ...
6
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2answers
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Is there a time difference between two points at the same longitude but at different latitudes?

Assume we have two cities A and B both at the same longitude (say $45^{0}$ E) but at different latitudes say $8^{0}$N and $90^{0}$ N. Can we get a time difference between these two cities. I raised ...
9
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2answers
711 views

Terrain correction for gravity data using Nagy, 1973

I am working with an algorithm for terrain correction of gravity data. I am using Nagy, 1973. However, I could not get the results I need. So, this is the problem. I have this function where x,y,z ...
9
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1answer
202 views

What is the current status of geophysical global cooling theory?

Plate tectonics effectively rubbished the theory of geophysical global cooling as a means of explaining many surface features on the Earth. However, this wiki says that the same process is responsible ...
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2answers
311 views

Next Ice age may be unavoidable

During the warm period before the most recent ice age, 120,000 years ago, roughly half of the Greenland ice sheet melted.This is thought to have been the cause of the last ice age. Question: If this ...
8
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3answers
470 views

Why is the elevation of the Iberian Peninsula so high?

The Iberian peninsula lies more than 600 m above sea level, on average, far above similar geological regions in western Europe. Even tectonically undeformed areas in the inner basins present a ...
4
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1answer
68 views

Where to start with P190s Seismic Navigation Files?

I have a few P190s navigation files from a 2D reflection seismic acquisition shoot and wondering what the best way was to extract UTM's (or latitude and longitude) and depth. I am reading through the ...
44
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12answers
30k views

Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?

I am in O'Fallon, Missouri and today it is -15 °C (5 °F) outside. I was taught water freezes at 0 °C (32 °F). I could understand if it was exactly 0 °C (32 °F) that the water might not be turning to ...
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0answers
61 views

meaning of Grid resolution [duplicate]

I have some queries regarding grid. What does this mean. The grid has spatial resolution of 1/2 degrees latitude × 2/3 degrees longitude.?
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1answer
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If we could stay still in the air. Would we be travel around the entire world in 24 hours? [closed]

I just wonder why, if we ourselves could stay still in the air (or just float in the air using something such as a hot air balloon). Why doesn't the world rotate around us, allowing us to travel ...
5
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1answer
107 views

Wobbly Tire Theory — Is there an existing theory that fits the following description?

I am not an earth scientist but for many years I have wondered about the following. I am curious if this has already been explored by scientists? If so, what is the theory formally called? and what is ...
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8answers
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How to quickly or easily prove the world is spherical?

A relative of mine has recently introduced me to the modern flat earth theory, which she believes in. Setting aside for the moment that it is ridiculous, and that sending up some balloons with cameras ...
8
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2answers
265 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 ...
3
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1answer
148 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 ...
6
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1answer
164 views

How did the intensity of Earth's magnetic field change through geological time?

Looking at the wikipedia article on the Earth's magnetic field, I see that its strength varies through time. How did Earth's magnetic field change throughout its history, from the beginning of the ...
6
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1answer
183 views

How high do you need to be to see Los Angeles from Washington DC?

If you were to stand on a tall building in Washington, DC and looked west, how tall would the building need to be to see Los Angeles? I would like answers based on if the world was flat and if the ...
3
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2answers
120 views

Is there a risk with putting out smouldering underground coal reserves? [closed]

According to this Discovery News video about Centralia Pennsylvania and other underground coal fires, there are many smouldering underground coal reserves making the land above it uninhabitable to ...
5
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1answer
216 views

Glossary of oil and gas industry geophysical terms

Reviewing market regulatory standards I came across the problem of finding a source that I could cite of concise, worldwide accepted industry geophysical terms. So far I know Schlumberger Oilfield ...
4
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1answer
536 views

Using the Born approximation in seismic inversion

In physics, the Born approximation allows us to separate the wave-function in terms of electronic and nuclear components. Why is this concept relevant in seismic inversion? For example in Colombi et ...
5
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1answer
784 views

Calculating magnetic declination for a non-axial dipole field

I'm trying to answer the following question: Compute the inclination and declination of the magnetic field that would be observed in Boulder, Colorado (40°N, 105°W) if the Earth’s field ...
3
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2answers
2k views

Effect on poles when Earth is not tilted [closed]

Say a Mars size object hits the Earth in such a way that it knocks the Earth in a straight 0 degree angle, and let's assume that we somehow do not go extinct. What would happen to the poles in this ...
3
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1answer
110 views

Quantitative mapping of air pollution Sifakis and Paronis

I am reading this paper about deriving AOT and I have found this ...
6
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1answer
199 views

Can the crust be compared to an arch?

Since tectonic plates are held together by lateral stress, friction, and gravity, and the Earth is a sphere, they work just like a full-circle arch or full-sphere dome. So can the crust be compared to ...
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1answer
550 views

Is it possible that the recent droughts are signs of epic crust failure? [closed]

The full question is: Is it possible that the recent, successive, long droughts from Australia to the West Coast of both American continents are signs of epic crust failure? The question is aimed ...
6
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1answer
192 views

Why do we measure eustatic sea-level from the center of earth?

Earth is rotating so it has a ellipsoidal shape. The measurement will therefore be different from equator and pole. So why do we measure eustatic sea-level from the center of earth?
6
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0answers
69 views

High-resolution laterolog array tool

Does anybody know if it is necessary to apply corrections to the reading given by this logging tool? Corrections such as bed thickness, borehole diameter, invasion, etc.? If so, is there anywhere I ...
9
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2answers
566 views

What are the striations or ridges in the eastern Pacific Ocean?

Messing around on Google Earth recently I noticed a number of striations in the Eastern Pacific. These appear in an East-West orientation and seem to start on the North and South American continental ...
6
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2answers
6k views

Does dirt compact itself over time? If so, how does this happen?

If I were to bury something 10 feet (~3 metres) underground, with loose soil on top, would the ground naturally compact itself over time, until whatever I had buried has dirt tightly pressing against ...
6
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1answer
251 views

What is the mass of our planet's atmosphere, hydrosphere, and cryosphere combined?

What is the mass of our planet's atmosphere, hydrosphere, and cryosphere combined? How accurate can our estimates be?
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1answer
137 views

Mechanism for Pluto's young surface

According to recent reports (e.g. in Nature), Pluto is geologically active. It has some mechanism by which it has "recycled" its surface. I originally thought we had a similar case to Jupiter's moon ...
4
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2answers
147 views

Is it dangerous to live in Seattle due to the earthquakes?

I'm considering a move/vacation to Seattle, and I'm concerned it may be dangerous due to the risk of an earthquake?
7
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1answer
632 views

petrophysical crossplots

I recently developed a computer program that generates some petrophysical and elastic parameters from well logs such as water saturation and hydrocarbon saturation, bulk volume, irreducible water ...
4
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1answer
61 views

State of Stress in rotated 2D system

I'm working on the rotation of the state of stress using the book Geodynamics of Turcotte page 101. The 2D coordinate system $x'$ and $y'$ is inclined at an angle $\phi$ with respect to the $x$, $y$ ...
5
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2answers
2k 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 ...
11
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2answers
293 views

Can rocks have pressure signatures?

Since rocks can have magnetic signatures, as is the case with paleomagnetism, can they store past pressures also? For example, when researchers are trying to determine past ocean levels, they ...
6
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1answer
136 views

How to define the force at the base of an oceanic crust

In the book of Turcotte and Schubert, Geodynamics I'm trying to solve problem 2.8. The pressure in the water, in the oceanic crust, and in the mantle beneath the oceanic crust are (from equation 2.19,...
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1answer
1k views

Available Matlab code to design Seismic Colored Inversion Operator?

I want to apply seismic colored inversion technique to my datasets. Is there a Matlab code available that I can easily use? Are there any other recommended codes to apply seismic colored inversion?

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