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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2answers
161 views

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 I generate a Moho depth model from seismic refraction data?

There are several permanent seismograph stations in Eastern Canada that have been recording arrival times for over 25 years. Using refracted Pn arrival times from natural earthquakes I would like to ...
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Over what scales can we begin to apply fluid dynamics to accurately model properties of the mantle?

Over what size temporal/spatial scales do geophysicists and geodynamicists begin to apply fluid dynamics to model the mantle rather than elastic/plastic deformation theory?
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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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What is the origin of oil?

Most people may believe that oil comes from dead plants and animals, but there are alternative theories that are known as Abiogenic Petroleum Origin. If oil in generated in this manner it could mean ...
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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 ...
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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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316 views

How to graph gravity as a function of depth, given radius and density?

I need to do this for a planet that has uniform density, and a planet that has two layers. For the first part, I was given that the density was 550 kg/m³, so I made one column in an Excel spreadsheet ...
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Aspiring Geophysicist

I am interested in becoming a geophysicist. I am currently doing my undergraduate degree in the UK but have not chosen a specialisation. Is it better to specialise in Earth Sciences as an undergrad or ...
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1answer
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Why doesn't Earth absorb our carbon emissions?

If we look at the carbon cycle, we see that man-made carbon emission only account for a tiny fraction of all $\text{CO}_2$ emissions. However, we see a steady rise in atmospheric $\text{CO}_2$-levels....
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1answer
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What is the difference between radiation balance and the global energy balance?

Looking at two diagrams below, they seem to depict the same system. How are they different? Why one is a radiation balance model and the other a global energy balance model? RADIATION BALANCE MODEL: ...
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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 ...
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680 views

What structures form due to the melting of subducting plates? [closed]

What structures form from the melting of subducting plates? Plutons, Accretionary wedges, Deep sea trenches, Faults?
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1answer
606 views

Rossby radius as horizontal scale

In the introduction of "Geographical and monthly variability of the first baroclinic Rossby radius of deformation in the South China Sea", the authors states: In both theoretical and observational ...
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2answers
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Is there any case that changed from earthquake safe zone to danger zone?

Is there any case that changed from earthquake safe zone to danger zone? As plates move, I think that earthquakes belt will change over time. But is there really a case in which the earthquake-safe ...
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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 ...
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Simple way to understand these narrow frequency peaks in recently published "ice shelf singing"?

The Earther.Gizmodo.com article Scientists Discover a Weird Noise Coming From Antarctic Ice Shelf links to the American Geophysical Union video (an more importantly audio) (AGU) This is what an ...
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1answer
108 views

Where on Earth is the highest none polar magnetic fields?

Is there anywhere that magnetic ore deposits are strong enough to have a magnetic field that would be stronger then Earths' magnetic poles by proximity? I'm not asking Where on Earth is the ...
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What exactly are enantiotropic and monotropic polymorphic transitions?

Recently, I've been studying the subject of polymorphism and met two important concepts, the monotropic and enantiotropic polymorphic transition types. However, I can't really seem to grasp the ...
3
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1answer
103 views

How much of the Earth's heat is caused by the hot centre?

What is the percentage of the Earth's warmth that the Earth's hot centre is responsible for? What would be the temperature of the atmosphere if the Earth's centre was 18° C (average temperature on the ...
3
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1answer
129 views

Do our continents lay on the mantle because solid silicon dioxide is less dense than its liquid form?

I don't know whether quartz behaves like ice or not, but could it be because silicon dioxide, which the continents are made of for a big part, is less dense - so the continents lay on top like ice on ...
3
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1answer
117 views

gamma-ray spectrum vs energy decay

I am going through An Introduction to Applied and Environmental Geophysics, a book by John Reynolds (2011), to better understand radiometrics and gamma-ray spectrometry. The author provides some ...
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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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Why do buoyantly rising mantle minerals melt, yet buoyantly rising atmospheric waters condense?

In the mantle, minerals contained in buoyant plumes of rock undergo phase changes from solid to liquid (decompression melting). In the atmosphere, waters contained in buoyant plumes of air undergo ...
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Quantitative mapping of air pollution Sifakis and Paronis

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

How does the changing seasons affect the large scale easterly flow of the ITCZ?

I am new to climate science and have been learning the basic picture of the intertropical convergence zone (ITCZ) and how this leads to the predominant easterly "trade winds". The picture that I ...
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1answer
63 views

Rain Water vs Sprinkler Irrigation

During the rainy season, the crops like corn, cotton are found to be growing faster. Studies shows that the thermoelectric fixation of gaseous Nitrogen during rain storm accelerates the plants growth ...
3
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1answer
62 views

Is there any possible future for high energy geophysics? If so how it is going to revolutionize our knowledge about Earth's interior?

How practice is to map/image the subsurface of the earth using the high energy particles like neutrinos? https://www.geosci-instrum-method-data-syst.net/special_issue2.html
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Plate boundary lon/lat data

I'm working on a map in GMT and am having trouble finding lon/lat data for the minor plate boundaries (specifically the adriatic). Is there a database I can refer to?
3
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1answer
334 views

Open source well information viewer

I am in the middle of a hobbyist experiment and would like suggestions on an open source HTML viewer for mud loggging, FMIs, lithology and seismic. I have used INT before but for this project I would ...
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1answer
147 views

Is there a high-temperature, non-magnetic glue that doesn't dissolve in water?

I have very small mineral samples, and I'm looking for a glue that can hold them through a sample preparation process that I'm doing: heating, polishing, and measuring magnetic moment. For that I want ...
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2answers
372 views

Conditions at the bottom of a VERY deep hole

I'm a science fiction author looking to describe what conditions might be like at the bottom of a cylindrical shaft ~ 30 meters across and ~ 35 km deep. It's located somewhere on the edge of ...
3
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1answer
657 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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1answer
53 views

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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1answer
111 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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1answer
74 views

Energy Density of Porous Rocks

It's very long, I know. But please, don't be discouraged from going through this question if you can help me. The question is at the second to the last paragraph, but you need to read through to ...
3
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1answer
73 views

If the top layer of a large river freezes, is the remainder's rate of flow affected?

This question is a hypothetical, and has to do with the notion of cheap, modular turbines that can be sunk and anchored to a specific depth in a body of water. Each would not generate much power, but ...
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1answer
95 views

Wave train 200 m/s meaning

I ran a 60 m line intended for surficial seismic refraction. Energization with hammer. 12 (10 hz vertical 5 m spaced) geophones and 5 shots (15 m spaced). Record length 0.5 s. Thanks to a borehole ...
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1answer
78 views

What voltage and/or amps cannot be found naturally?

Electricity can come in many forms on Earth but when is amps and/or voltage limited physically on Earth? In other words, what voltage arises naturally on Earth?
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1answer
150 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 ...
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42 views

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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37 views

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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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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Hypothetically, in the near future, could gas hydrate pingos erupt?

Could gas hydrate pingos erupt? If so, how quickly? And how much CH4 could they release? I'm sorry if the questions sounds silly. I'm new here and I don't know much about gas hydrates and oceanography....
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1answer
86 views

How to measure global temperature?

people always talk about global temperature (such as the global temperature goal of 1,5 K) - but how is this value achieved? It seems to me that it clearly depends on where the measuring stations are, ...
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How long for tectonic plates to develop from a planetary, molten planetary surface?

On Earth or an Earth-like planet, how long does it take for a molten surface to solidify into planetary crust, and how long does it take for that crust to develop into tectonic plates?
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Cratonization - how did the Archean cratons form?

Before the onset of modern style plate tectonics and the Wilson cycles in the late Archean, it is thought that smaller units of continental crust, called cratons, roamed the oceanic crust over a more ...
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What is the minimum temperature difference to drive mantle convection?

The condition for convection to cease is that the Rayleigh number $$\mathrm{Ra}=\frac{g\rho\alpha L^3\Delta T}{\kappa\nu}\lessapprox 10^3.$$ For the Earth's mantle I have seen estimates of $\mathrm{Ra}...
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Why an inertial gyro has a frequency and a geostrophic gyro does not?

Inertial flow is given by the balance between Coriolis and centrifugal forces. A geostrophic flow is given by a balance between Coriolis and the gradients of pressure. The frequency of the inertial ...

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