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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39 views

What is common in financial market crash and earthquake/Volcanic eruption? [closed]

Good day, I have two part question. I read all three phenomenon follow similar pattern if you do timeseries analysis. Is this true ? Where would be I able to find such data for earthquake/eruption ? ...
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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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Geo-Spherical shape of Earth

I know that the best possible approximation of the shape of earth is an oblate sphere. But people also call it as geo-spherical shape of the Earth. What is the meaning of geospherical shape? Does this ...
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How much water is the atmosphere losing to space?

Up until recently, I was under a (wrong) impression that the amount of planetary cumulative water resources was finite as I believed its escape from the atmosphere was impossible. I believed that, ...
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2answers
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Why is colored seismic inversion called 'colored'?

One of the seismic inversion algorithms is called 'colored' inversion. It is performed in the frequency domain and the point is in building an operator that directly transforms a seismic trace into ...
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1answer
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Where can I find an anisotropic PREM-like model for Earth's interior?

So, I just discovered PREM (the Preliminary reference Earth model) which models the density distribution of matter inside the Earth to any depth. The PREM is very convenient but since it only depends ...
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1answer
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Elevation accuracy to distinguish maximal gravity anomaly of a sphere with 50% hematite

Question: What is the accuracy required in elevation to distinguish the maximal gravity anomaly of a spherical 50% Haematite (Iron mineral) ore with a radius of <...
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Coriolis parameter approximations

When solving equations involving the Coriolis parameter $f = 2\Omega\sin{\varphi}$, I often see the $f$-plane (constant) or the $\beta$-plane (Taylor expansion) approximations. If I'm solving ...
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1answer
113 views

When will the Earth lose its magnetic field?

Mars lost its magnetic field 4.5 billion years ago according to this article: Mars lost its global magnetic field during the time of this heightened activity. After 500 million years, the Martian ...
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Range of frequencies of the Schumann resonance?

Crossposted at Physics SE As the surface-ionospheric gap acts as a resonator for electromagnetic waves, it should have several harmonic values from the base, fundamental frequency of 7.83 Hz. These ...
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1answer
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IGRF -13 Geomagnetic field, Calculating Partial Derivatives of Legendre Polynomials

I have been trying to implement the IGRF-13 geomagnetic model on my own in C code. I have followed the equations from the website below and I am getting correct results for the B$_{\phi}$ and Br ...
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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 ...
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Do greenhouse gases absorb and re-emit photons or reflect them diffusely? Or both? (CO2, CH4, H2O, N20, HFC-134a, etc.)

Also, would it matter if a particular type of greenhouse gas molecule reflected rather than absorbed and then re-emitted light? Would its GWP be higher or lower? Perhaps this is more of a pure ...
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How can you find the seismic intensity at a given point?

Given the distance, material, and seismic intensity at the epicenter, can you calculate the seismic intensity at a given point?
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3answers
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Are there any techniques for imaging the deep Earth besides seismic waves?

It is well-known that we can learn a lot about the structure of the lower crust, mantle, and core by observing the ways in which they refract different kinds of seismic waves. Do we have any other ...
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What are the boundary conditions for Navier's Equations of motion in seismic?

Navier's equations of motion in seismic have 3 solutions, according to how it is resolved (boundary conditions): for Vp (compression waves) for Vs (shear waves) for Vr (Rayleigh waves) I know the ...
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1answer
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What is the relationship between raw seismic data, CMP Stacking, NMO & Machine Learning

I recently joined a geophysics project to assist with some of their machine learning modeling but am trying to gather the domain knowledge required to participate. Something I don't quite understand ...
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1answer
50 views

Can Hydrocarbons be beneficial? [duplicate]

Do these “fossil fuels” underground help maintain homeostasis in microbial ecosystem or aid in the growth of flora etc? Or are these substances: coal, animal remains and natural gas detrimental even ...
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Why does sea level correspond to boundary between oceanic and continental crust?

Is it a coincidence? the first is determined by the amount of water on the Earth and the second comes from evolution of tectonic plates. Still, oceans seem to fill exactly the oceanic crust.
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Can an igneous rock have a Vp of less than 1000 m/s and need blasting to excavate?

I have run a 60 m refraction seismic line on a mountain summit. The environment was noisy (wind would be the principal agent) and quite difficult to pick first arrivals. It resulted in 800 m/s. A ...
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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
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How to interperet audio magnetotelluric results?

I'm newbie in filed of Geophysics science. I will be grateful if you could help me to understand this chart what does line 12 or Line 11 mean? what about line15-14? How to identify the depths? what ...
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How is the mass of the Earth determined?

According to textbook knowledge, the mass of the earth is about $6 × 10^{24}\,\mathrm{kg}$. How is this number determined when one cannot just weight the earth using regular scales?
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1answer
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Can ultrasounds be used to map the density of large underground regions?

This question arose from a related one at Physics.SE, along with my own personal quest to better understand mineralogical prospecting. I want to know if some kind of ultrasound machine can determine ...
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How long do geostrophic currents last?

My professor posed this question, without any relevant material. I suppose the currents last until the density gradient is neutralized, but I can't find any literature nor articles on this, regarding ...
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Understanding the EM survey results

I have contour maps showing conductivity and in-phase data from an electromagnetic survey done on a ground, where, supposedly, an underground sewer system is running horizontally across the survey ...
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3answers
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How many days has it been since the Cambrian explosion?

I want to know how to calculate the number of days since an event in Earth's past, and am using the Cambrian explosion as an example. I define a day to be one rotation of Earth with respect to the ...
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1answer
563 views

What affects where a terrain will be rocky or grassy?

I’m working on a terrain generator and I now need to color the terrain to be rock, grass, or snow. Ignoring snow for now, at first I thought I’d make flatter areas grass and make steeper areas rock. ...
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0answers
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Construction of a drift curve in the well tie calibration and how to interpret it?. Sonic calibration vs checkshot calibration

Good afternoon. Inside the creation of the synthetic seismogram some softwares have the option to run what is called "sonic calibration" or "checkshot calibration". I have some questions: 1)why some ...
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What is the electrical conductivity of a liquid Komatiite?

I am searching for previous work that has determined the electrical conductivity range for komatiites at the surface. Does anyone have some values or references?
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How hot would days get if it were always the solstice in the northern hemisphere?

Imagine the Earth's axis of rotation were to precess in synch with the orbit of earth around the sun so the north pole always pointed towards the sun (same current axial tilt of about 23 degrees). ...
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Why do we consider hydrostatic pressure and lithostatic pressure separately?

In petroleum geology, why do we consider hydrostatic pressure and lithostatic pressure separately? Surely the pressure at any point, whether fluid or rock, at depth is simply equal the weight of all ...
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Equations for Milankovitch Factors?

Are there equations for the radiative forcings of the three Milankovitch factors at any given time? Or a database of values?
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1answer
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Why should wellbores be supported by pressure, but not mine tunnels?

I recently read about safe mud window - it states that the mud pressure in a wellbore should be high enough to prevent well collapse, and should not exceed the formation's fracture pressure. But ...
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Performing time-frequency analysis (FTAN)

I am trying to do ambient noise tomography and I am quite confused on how to perform time-frequency analysis (FTAN) as shown in figure 13b and 13d of this paper by Bensen et al.. I am using Python and ...
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1answer
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Q factor estimation from VSP

in seismic data processing there is a step of calculating the absorption represented By Q value which is Q factor , how we can estimate it from VSP ! thank you.
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How much would the ground be displaced in a magnitude 11 earthquake?

In a magnitude 5 earthquake, the ground shakes violently and it's often impossible to stay upright. This is caused by about 50-120 cm of displacement of the ground. But how much would the ground move ...
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Quality control in Seismic Acquisition - shot offset shift

I have a problem with seismic data where the minimum offset of the shot is not centered at the nearest receiver, this shift can be for 3 traces 2 or one and maybe more in the two sides !! So is there ...
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1answer
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Can a planet be heated by the green house effect to a temperature higher than that created by its incident and net absorbed, peak external radiation?

In that the green house effect, as caused by various atmospheric gases (e.g., H2O, CO2, CH4, etc), acts as an insulating layer which only retards the escape of heat from the planet, it would seem that ...
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3answers
239 views

How Can We Establish Precisely What Earth's Core is Made Of?

The consensus view is that that the Earths core is composed mainly of iron alloyed with about 10 percent nickel and traces of other heavy metals, but I have seen at least one account which says it is ...
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2answers
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How much of all current energy on earth arrived as sunlight vs. as kinetic energy during formation?

For example, sunlight captured by plants would count in the "arrived as sunlight" category, whilst heat energy in the core of the earth would count in the "kinetic energy during ...
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1answer
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What would happen if the inner core bulged and moved a tiny bit?

The inner core is solid only because of the very high pressure of the outer core and mantle . Say, if the inner core moved a teeny tiny bit would some of it liquify and melt? Or does it stay solid? ...
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1answer
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Will California become a subduction zone in the distant future

California is one of the few places in the world that lie on a transform fault. My question is why considering the fact that North American Plate is moving westward shouldn't California be a ...
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3answers
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Is Mount Everest currently becoming taller or shorter every year?

Is Mount Everest becoming taller or shorter every year? By how much? I would like an explanation in terms of tectonic plate movement if possible. Source: IamKatieHoffman.com
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How do the Andes get so high?

I'm interested in the limiting factors on the height of mountains. There is a very good explanation at https://www.quora.com/How-tall-can-a-mountain-become-on-Earth-Neil-deGrasse-Tyson-says-Mount-...
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3answers
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Does gravity increase the closer to the core you get?

Or does the mantle and crust above you counteract the increase at one point and it actually decreases?
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1answer
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Does the shear modulus of silicate minerals vary significantly with changes in P and T?

I know that the bulk modulus, K, varies with pressure and temperature for silicate minerals and liquids, but what about the shear modulus? If so, is the change drastic for changes from standard ...
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Conversion of SEG-Y relative to MSL

I am working on the conversion of CSF file from SonarWiz into SEG-Y data. However, it comes back always related to the Sensor depth/altitude and never to the MSL. I have tried changing the bytes from ...
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2answers
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Relationship Between Ratio of Atmospheric Gases and Ocean Gases

A version of this question was posted in Chemistry SE and Worldbuilding SE but I've been told it wasn't appropriate to either SE. I was told to give this SE a chance. If you think it doesn't belong on ...
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Differentiate correlation of between depth and bouguer anomaly

Assume we measure bouguer anomaly (g) and depth (H) of the certain horizon through a profile at each point. Based on data we get a correlation between H and g and express it with a polynomial equation ...

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