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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What are the fields in Petrel's IESX seismic horizon file?

I have a text file containing 23 seismic horizons from Petrel, Schlumberger's seismic earth interpretation and modelling tool, using the 2D IESX format. Here are the first few rows: ...
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Why do Euler poles for plate motions not stay fixed in time?

Surely if a plate motion is a straight line across a sphere, this can be described by a fixed Euler pole, however I've been reading about a problem which I confess I don't fully understand which is ...
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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 ...
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Cooling time of basalt flows?

In places like the Giant's causeway in Ireland (Antrim basalts) there are columnar basalt flows of 100 metres or more. I'm aware that the cooling mechanism is complex, but is there any rough and ready ...
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Why does part of the P-wave convert into a S-wave with an increase of incidence angle?

With the increase of incidence angle, a portion of a P-wave converts into a S-wave, how does this behaviour occur?
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In quasi-geostrophic frontogenesis, what happens if the potential vorticity is negative?

In particular, what happens if the Sawyer–Eliassen equation cannot be solved? I know that a condition for the Sawyer–Eliassen equation to have a solution is $F^2 N^2 - S^4 >0$, which means that the ...
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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 ...
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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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Is there a time difference between two points at the same longitude but at different latitudes?

Assume we have two cities A and B both at the same longitude (say $45^{0}$ E) but at different latitudes say $8^{0}$N and $90^{0}$ N. Can we get a time difference between these two cities. I raised ...
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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 the Ring of Fire there? [duplicate]

The Ring of Fire goes through the places that have the most earthquakes. Why is the Ring of Fire there, not somewhere else? Any help would be appreciated!
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How to convert mol/m^2 to total mass ( e.g gram, kg etc )?

I want to calculate the total $\rm{NO_2}$ amount in a year using satellite Sentinel-5p NO2 dataset. But the problem is sentinel satellite data stored in $\rm\frac{mol}{m^2}$ unit. But I have to ...
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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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Why are pole reversals not more detrimental to life?

This question is linked to the following question, and has two parts. Mars interdicts approximately 40% of the radiation (per square meter) of the sun that Earth does. It has been claimed that Mars ...
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1answer
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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 ...
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1answer
202 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 ...
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492 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 ...
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What is (negative) wind stress curl?

I'm currently doing research for a paper in school where we need to research on a university-like level. When I read the paper Causes and impacts of the 2014 warm anomaly in the NE Pacific, I found ...
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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 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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336 views

Hydrocarbon potential in Ganges Brahmaputra delta

According to Curray (1991): Total sediment thickness beneath the [Ganges–Brahmaputra delta] southeast of the hingezone exceeds 16 km... Considering a normal geothermal gradient and data for oil ...
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Is the Cameroon Line still an active rift zone?

The Cameroon Line is described by the Oregon State University's Volcano World webpage What is known about the volcanoes of Cameroon? as a a chain of volcanoes extending from Annobon Island in the ...
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Would it be wise to monitor real time human activity to anticipate earthquakes?

Documented strange behaviors of animals before an earthquake could invite us to believe that some of them anticipate tectonic activity. We also know that human complex organization makes it difficult ...
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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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What theories exist connecting volcano temperatures to eruption probabilities?

Wikipedia names thermal monitoring as one of the methods for predicting volcanic eruptions. I was able to find some papers (First, Second) on such thermometry and while they are challenging (I retired ...
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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 ...
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1answer
105 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 ...
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1answer
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Seismic migration concepts

In Dr Hua-Wei Zhou's book Practical Seismic Data Analysis (2014), he includes and explains figures from previous classic works (i.e. Schneider, 1971) in order to describe migration from a fundamental ...
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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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How much does the electric current within the Earth' core depend on the axis of the Earth's orbit?

I always thought that the movement of the iron core was caused by the axis of orbit of the Earth. Probably that isn't quite as true as I read, because in the core the iron material undergoes types of ...
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195 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 ...
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291 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?
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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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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
414 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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1answer
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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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1answer
520 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.
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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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2answers
222 views

How can I calculate the sensitivity of a seismometer?

I would like to know if a specific seismometer can measure 1 micron/sec velocity. I have a few specs from the datasheet but I'm not a seismologist and am trying to figure out how to relate the specs ...
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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 ...
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779 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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639 views

Megathrust earthquakes on subduction zones

I am a beginner in geology and earthquake studies, and learning about subduction zones recently. Question is: do large earthquakes (sometimes referred to as megathrust quakes) occur on any point in ...
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Why can Thomsen's parameter $\epsilon$ be negative in VTI media?

I just got several well log curves, some of which are Thomsen's parameters. They are a result of interpretation of Sonic Scanner tool measurements (Schlumberger). Negative epsilon values appear quite ...
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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 ...
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Is an underground mine collapse or a tunnel collapse called a sinkhole?

Imagine there's an underground man made structure e.g. a tunnel or an underground train station that collapses creating a depression in the surface. Would that technically be called a sinkhole? What ...
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Does the Earth 'Flare' like the Sun does?

Solar Flares are a commonly discussed phenomenon, which have effects ranging from geomagnetic storms to radio disruptions to absolutely nothing noticeable. Given that part of the core of the Earth ...
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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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SEGD and SEGY recorded data

What is the difference between a segd recorded data and a segy recorded data and can we convert from segd to segy and vice versa?
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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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What percentage of the earth's surface is covered by 2D or 3D reflection seismic data?

It was recently asserted to me that we have no idea what Planet Earth really looks like below our feet. I responded that (mainly oil-industry) seismic data covers a vast area and so actually we have a ...

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