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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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8
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3answers
394 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 ...
42
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12answers
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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
50 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
127 views

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
106 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
6k views

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 ...
6
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1answer
240 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
140 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
155 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
182 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
108 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
206 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
514 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
754 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
108 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
194 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 ...
-6
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1answer
522 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
190 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
68 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
512 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
5k 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
237 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?
11
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1answer
136 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
143 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
616 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
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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
290 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
132 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?
6
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1answer
423 views

Why is it necessary in seismic imaging to calculate an image of reflection coefficients when one of the inputs is the velocity model?

Note: I'm not at all an expert in this field. I read in the first few pages of Robein (2010; Seismic Imaging, A Review of the Techniques, their Principles, Merits and Limitations, EAGE) that both ...
7
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1answer
195 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 ...
6
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1answer
100 views

Querying Seismic Databases

I'm trying to find 3-component records of the P-wave arrivals of a variety of earthquakes at seismic stations (specific earthquakes or stations aren't important, I just want a small library of these ...
7
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1answer
82 views

Publicly-available real-time world-wide seismographic information?

Is there a list of websites supplying real time seismographic information for around the world? I could find for specific places. But I'm looking for a list so I can check for anywhere (providing, of ...
31
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3answers
9k views

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

I took a tour of a cave in northern California last weekend. The tour guide asked us, "If an earthquake occurred, what would we feel in here?" My answer was, "fear," but she said we would feel ...
10
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1answer
1k views

What are the challenges in predicting lithology directly from acoustic impedance?

Seismic inversion methods help to visualize the subsurface layers of the earth in terms of petrophysical properties (e.g. impedance). Still some geophysicists use the final inverted impedance model in ...
11
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2answers
864 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 ...
9
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5answers
4k views

Why does New Zealand and cold countries have volcanoes?

I understand that volcanoes are caused by the heat that causes high intense pressure below the Earth's surface. This intense pressure gets released and causes magna which becomes hot lava to flow out ...
9
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2answers
281 views

Impact craters vs volcanic explosions on Mars

A maar is a shallow volcanic crater with steep sides that is surrounded by tephra deposits. The tephra deposits are thickest near the crater and decrease with distance from the crater. Source: http://...
6
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1answer
75 views

Mars maar craters explosive style formation gravitational effect

"Maars usually form when magma rises within a fissure and interacts with groundwater. If groundwater ceases to interact with magma at times during the eruption, continued magma ascent to the surface ...
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1answer
2k views

What is the meaning of seismic spectral blueing?

What is the meaning of seismic spectral blueing? Please cite any good introductory materials if possible.
8
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1answer
569 views

Books for learning applied seismic geophysics

I am a software developer trying to learn applied geophysics. Specifically I am interested in seismic attributes. I have a strong background in mathematics and signal processing and therefore grasp ...
8
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1answer
2k views

How do I extract seismic amplitude on an interpreted horizon?

It seems that seismic amplitude extracted on an interpreted horizon is good for showing channels. E.g.:http://seismicatlas.org/entity?id=98a83c60-ea81-47cc-9304-6041f6ec5277. It seems that often the ...
6
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1answer
429 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.
11
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5answers
6k views

Why is continental crust less dense than oceanic?

Why is it that continental crust is less dense than oceanic, where in fact continental crust is thicker than oceanic crust?
6
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3answers
406 views

Simulating the earths crust

I would like to create a computer simulation which would fold two plane-ish surfaces into two crumpled-ish surfaces. This in order to simulate the earths crust movement and collisions resulting in ...
10
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1answer
577 views

Stochastic seismic inversion

Could anyone recommend a free and reliable software capable of Stochastic seismic inversion for my project? am aware that Petrel is capable of Genetic inversion based on a non-linear multi-trace ...
10
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1answer
2k views

How does one determine the optimum offset in a seismic survey?

I was going through a report on MASW (Multi Station Analysis of Surface Wave) and found this "To avoid the aliasing in the space domain, geophone spacing (Δx) needs to be less than half of the ...