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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Finding out actual dip and dip direction of refractor

We have two traveltive curves for first arrivals (direct and refracted) from a dipping refractor in the forward and reverse directions along a profile line. my question is: Is there a logical way (non-...
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Effects of Centrifugal Force on Gravity Vectors?

I've been asked this question twice now from our favourite science denying community, and I don't know how to parse it. I can do centrifugal force and gravity given mass, but have never tried to even ...
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What is the largest hurricane possible?

With Earth getting hotter and hurricanes also getting larger I wonder; Is there a limit on how big a hurricane can physically get?
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where are the poles of rotation of the tectonic plates located?

Euler's "fixed point" theorem ... can be stated as: The most general displacement of a rigid body over the surface of a sphere can be regarded as a rotation about a suitable axis which passes ...
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Zoeppritz equations derivation

I have been long looking for the derivations and step by step explanation of Zoeppritz matrix but either internet is full of final versions or I can’t find it...I would be very thankful if anyone can ...
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Can a 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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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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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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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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129 views

Does subduction of continental crust happen at continental-continental convergent boundaries?

What exactly happens at a continental-continental (cc) convergent boundary? I read myself through the web for the last few days and what I came up with is that such a boundary will start as an oceanic-...
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Transmitter receiver coil separation for Electromagnetic Terrain Conductivity Measurement

Why increasing transmitter-receiver coil separation in EM survey (EM31, also here) increases depth of penetration? Suppose there is a horizontal flat conductive layer underneath a flat resistive ...
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If the accuracy of measurement of the earth's volume is not known, how can scientists assert that the earth is not expanding?

Volcanic eruptions, undersea earthquakes, fissures in the crust, meteoroid accumulation could all be seen as empirical evidence of expansion of the earth. Sink holes and other phenomena could be ...
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48 views

Barotropic vorticity equation

I came across the barotropic vorticity equation (below) in Sakamoto (2002) and I cannot figure it out. The notation is not clear to me. How can it be derived from the Navier-Stokes equation? $$ \beta\...
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121 views

How does multiple layer seismic reflection work? How do we distinguish arrivals from different layers and their velocities?

Whenever we are investigating multiple layer interfaces in a seismic reflection survey the root-mean-squared velocity is often employed to deduce travel time to a certain n-th layer and also to deduce ...
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Can extratropical cyclones force global cooling?

We are living in a historical period of global warming since about 20,000 years ago. This global warming period is one of about ten in human history. Those periods may very well be forced to start by ...
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Travel Times for Seismic Wave Types - Why reflected t-x plot curves

I do not understand how the reflected wave in a seismic survey has a steepening slope (slows down) Please bear with me as I lay out my thoughts because I feel like I can grasp all of this except this ...
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47 views

Near-Surface Investigations: FWI vs. MASW

MASW is a common processing method for civil/geotechnical and even for oil/gas exploration (usually weathering static corrections) applications. In my experience, it seems to work well for most ...
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Which ocean is going to be swallowed by the Supercontinent Cycle, Atlantic or Pacific?

The register shows several supercontinents have been formed on Earth's History: "The most recent supercontinent, Pangaea, formed about 300 million years ago (0.3 Ga). There are two different ...
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Why Earth's outer core does not dissolve into the mantle?

It is well accepted that the outer core is made out of liquid iron and nickel, and as everything else it should tend to reach chemical equilibrium with its surrounding. In particular, I would expect ...
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Why the “Mission to Earth’s core” proposal suggests using liquid iron instead of lead?

Nature communications article "Mission to Earth's core — a modest proposal", suggests placing a large volume of liquid iron in a crack and let it sink all the way to the Earth's core, carrying along a ...
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67 views

Hydrology- flow accumulation

I'm not specialist in hydrology, and I would be very grateful if you answer my question: What is flow accumulation in hydrology? Why algorithms used to calculate it over a raster DEM don't take ...
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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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78 views

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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167 views

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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428 views

What will be the temperature on Earth when Sun finishes its main sequence?

We know that presently Sun is 4.5 billion years into its main sequence. It has another 5 billion years before it enters the Red Giant phase. We also know that Sun's luminosity increases by 10% every ...
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Seismic data acquisition: reliability of high-bandwidth data

In my research, finding and understanding info relating to the lower end of (conventional) surface seismic data acquisition (i.e. 15 - 1 Hz) is relatively simple. However, when I look at specs for a ...
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transition elastic deformation to flow

Let's assume a small (and smooth) vertical deformation of the seabed. If done quickly, I can consider it a vertical force generating an acoustic wave in the water, where every particle of water ...
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167 views

Why did the carboniferous period have so much atmospheric oxygen?

Even if all the carbon dioxide (which makes up less than 1% of the atmosphere) in the air were sequestered by plants, would the atmosphere not remain about 21% oxygen? Why did the carboniferous period ...
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Time standard for IERS Bulletin A

IERS Bulletin A and Bulletin B contains Earth orientation parameters. These include the time difference between UT1 and UTC and pole position. The values for these parameters are listed once per day, ...
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42 views

Love-Wave Propagation

Love-waves cannot exist in a half-space. Layering must be present and there also must be accompanied impedance contrasts associated with the layering. Because layering naturally induces seismic ...
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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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Determining the spatial orientation of a fault given ground acceleration magnitude in different directions

Accelerographs measure ground acceleration in three different components of motion: east-west, north-south, and vertically (up-down). I know that fault orientation is important here, so let's say we ...
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274 views

Unwarranted claim of higher degree of accuracy in zircon geochronology

The uncertainty in the half life of uranium-238 is stated at 0.05% [1]. The same paper gives the date 251.941 myr ± 31 kyr. 251.941 $\times$ 0.05% = 125 kyr. How are the authors justified in ...
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Would oceans regenerate if removed?

On Earth, there is enough Hydrogen and Oxygen to make 13,88 million km$^3$ of water (calculation below). However, oceans contain only a tenth of that. Clearly, most of the hydrogen must be stored in ...
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How do people determine initial ratio of the parent nuclide and daughter product in radiometric dating?

I understand that we have zircon crystals that prevent entering or leaving of nuclide or lead after forming. But how cand we understand what was the initial ratio?
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Difference between landslide waves and earth quake waves

I am new to this field, recently started working on landslide monitoring mainly in signal processing part. I have the following questions? 1.Will each land slide and every vibration have p wave, s ...
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75 views

Volcanic Eruption Calculation?

I was trying to find the amount of energy created during a volcanic explosion, I have been looking around, There was one formula I found where I could use the Kinetic Energy, which is $KE=\frac{1}{2}...
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104 views

Is it possible to create ice in poles? [closed]

Is it possible that human can built under the poles a controlled system to create again artificial icebergs? In order keep tight the melting ice and reduce the sea level? Can this system impact the ...
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189 views

Quality control in Seismic Acquisition - How much data is required?

When it comes to land or marine acquisition (oil exploration, for instance), I can see from literature that quality control (QC) is performed during the survey to ensure that the seismic traces ...
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304 views

Why Do Supercontinents Form? [duplicate]

It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future. ...
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63 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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63 views

Which is naturally more radioactive: a tertiary or cretaceous sandstone? Why?

I've come across this question in a Petrophysics exercise regarding the Gamma Ray well logging. And I don't know how to solve it. This is the "believed" AFAIK session Natural radioactivity on a ...
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411 views

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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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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85 views

Is this a rock with metal or gold? [closed]

I found these really hard rock while i was excavating. It caught my attention the different colors.
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72 views

What kind of purple stone is this? [closed]

I found this stone and I do not know what type of stone is this?
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How much does the Earth's center of mass move around?

How much does the Earth's center of mass move around relative to the most stationary objects on the surface? I'm wondering whether the molten outer core has enough asymmetry to move the center of ...
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181 views

If all the world's ice were to melt, would this shift the earth's centre of gravity with consequential effects on sea levels?

This question on Maths SE asked how we might calculate the effect on sea level if all the world's ice (ie including the whole Antarctic ice sheet) were to melt. I posted an answer containing ...
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Is there a “submerged object” in Australia that causes a magnetic deviation of 20 degrees?

This answer quotes this blogpost as an example of a magnetic anomaly: Basalt formation, “Mt. Jim”, in remote north-east Victoria, Australia, has a magnetic anomaly -20 degree magnetic compass ...