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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Why is the inside of the Earth so hot?
I have heard that the Earth is made up of four layers, being the crust, the mantle, the outer core and the inner core. I have also heard that the Earth's temperature increases as you move from the ...
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Did the impact event that caused the Chicxulub-Crater definitively and single-handedly cause the Cretaceous-Paleogene extinction?
Opinions abound on the web. What is the state of the current science regarding this theory and what is the best evidence? Is the theory gaining or losing traction? If it's losing what's the best of ...
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When a tectonic plate subducts, does any of the subducted material melt, or is it just the mantle above the subducted slab that melts?
I know that water released from oceanic crust causes melting of the mantle in subduction zones, but does any part of the subducted slab melt as well - such as the sediments on the slab or the basalt? ...
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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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How are subsurface wave speeds determined without subsurface sensors?
This is something I've never quite understood from a geology class I took years ago:
Consider the following picture (courtesy of wikipedia)
Obviously, we can't possibly have sensors deep in the ...
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Why is ocean surface velocity around 3% of wind velocity?
Many introductory level textbooks suggest that, as a rule of thumb, the velocity of the ocean surface is around 3% the wind velocity at 10 meters above the sea surface.
For instance, Ocean ...
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What do the derivative or the integral of amplitude of a seismogram mean?
I'm doing a project in which I'm analyzing earthquake seismogram waves. I used a program to graph the exact amplitudes and how they changed over the course of a single earthquake. For the project I ...
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Should one extract wavelet from seismic or well log for the generation of synthetic traces?
Synthetics are generated by convolving reflectivity series with the known wavelet. I have seen most of the wavelet are extracted from seismic data itself. Is there any hard and fast rule, or can one ...
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Why does seismic activity shed light on the inner core rigidity?
Reading Introduction to Geology (MIT 2005) and Wikipedia's article on Earth's inner core, it is specified that:
Earth was discovered to have a solid inner core distinct from its liquid outer
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When will the Final Ice Age happen?
As the Sun's luminosity slowly rises, the Earth's surface temperature will climb. Will Earth ever be too warm to have any more glacial periods? If so, when will that be?
Edit: The existing answer ...
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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?
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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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Is the epicenter always directly above the hypocenter?
All the graphics I've seen showing epicenters with a hypocenter (labeled focus in the graph below) appear to show that epicenters are always directly above their related hypocenters. Is this correct?
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What happens to the higher frequency content of the tremors associated with a volcanic eruption?
From [1]:
The main characteristics of volcanic tremor depend strongly on
whether a volcano is erupting explosively and on the intensity of the
event. Long before an eruption, tremor is ‘narrow-band’ (...
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Is the Earth heated up by the tides?
Reading about moons of other planets they often get heated up by the tides so for example Io and Europe of Jupiter get friction by which eruptions and liquid water can arise. But is there also an ...
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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 ...
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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 ...
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Why is the lithostatic pressure gradient 1 psi/ft? How is it derived from density?
Why is the geostatic (or is it the lithostatic?) gradient 1 psi/ft? How is that derived from g/cc? Thanks.
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Changes in Earth's orbital and rotation speeds
What are the Earth's maximum and minimum orbital speeds around the Sun?
Is there any way to calculate orbital speed at any point of Earth's orbit? Is there a way to relate this to the calendar?
Does ...
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What "g" would be needed to keep helium on Earth?
I know that helium is a very light and rare gas on Earth because Earths gravity is not strong enough to keep it. Instead, helium and hydrogen are rising through the atmosphere and escape into outer ...
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Does the Coriolis Effect affect a wind from East to West?
I'm studying meteorology for a pilot license and there I was taught as a rule of thumb that wind at higher altitudes is approximately turned 30° clockwise to the wind on the surface due to the ...
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Are the oceans rising or the continents going down? How can we know?
The century old sustained rising of oceans, at a rate of 2-4 mm/y, remains a unexplained phenomenon; there is no correlation with temperature variations, so it is not due to the thermal variation of ...
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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.
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How do seismic charges help to investigate the subsurface?
In the film Kong: Skull Island, scientists investigate an island's structure by dropping explosive charges from helicopters:
Source: YouTube trailer
In reality, geophysicists do something similar ...
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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?
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Why doesn't the Earth's outer core 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 is ground water rising on these forest rings?
I am seeking a physical explanation for this;
There is huge amount of such a Forest rings in Earth; (Link to Google Maps to one ~400 m Ring)
They range in diameter from 30 metres to 2 kilometres, ...
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Is there evidence to delineate where a southern extension of the East African Rift 'plate boundary' is developing?
The East African Rift system is described by James Wood and Alex Guth of Michigan Technological University in the Geology.com web-article East Africa's Great Rift Valley: A Complex Rift System as ...
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Could evidence of a signal from an exocivilization be found in the geologic record?
We know that the current SETI efforts have not found evidence for the existence of intelligent exo-civilizations (XCIV). There also has not been any evidence found of ancient non-human civilizations ...
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Thermal expansion of Earth
Matter tends to change its volume in response to changes in temperature--or, hot things tend to be expanded. Is the thermal expansion of Earth significant?
That is, is it significant when compared ...
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What is the tectonic explanation for parallel ridges in the Arctic Ocean?
Looking at a map of the underwater features of the Arctic Ocean reveals three roughly parallel ridges, separated by basins (see image below):
Image source
The three ridges, as labelled are the Alpha ...
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How can we measure the thickness of the Earth's mantle? [duplicate]
According to Wikipedia the earth's mantle is approximately 2900 km (1,800 miles) thick.
How is it possible to achieve such measurements?
Obviously we haven't sent anything down that far to check.
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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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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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Why are all rainbows are not the same? [closed]
How does these rainbows water drops differ? I know it has to do with the size of water drops refracting light.
Is there a formula that determines the type of rainbow?
Icebow
Unlike this questions ...
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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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Forest rings shape regularity
In the answer to "Why is ground water rising on these forest rings?" it is written:
these rings are too numerous and too regular in shape to be related to either kimberlites or (even more ...
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What is the highest balloons possible in a chain?
The BU60-1 balloon attained an altitude of 53.0 km (32.9 mi; 173,900 ft).
Weather permitting, would a series of climbable balloons in a chain be able to be linked from the ground to that height of ...
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What are some good resources to learn about geophysics? [closed]
What are some good textbooks and online resources for learning about geophysics? That is, physics, as it relates to the earth's geology, shape, and internal structure.
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Can a shock wave travel around the Earth's curvature?
Can an explosion be felt in the ground on the opposite side of the Earth like from an asteroid? Would planes in the air on that side of the Earth be able to survive?
Does the shock waive follow the ...
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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 ...
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