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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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How can we determine the size and composition of Earth's inner core?

From Wikipedia: Earth's inner core is Earth's innermost part and is a primarily solid ball with a radius of about 1,220 km (760 mi). (This is about 70% of the Moon's radius.) It is believed to consist ...
Ben A. Noone's user avatar
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26 votes
7 answers
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Could the Earth's core lose its heat?

Will all the drilling and digging to use the Earth's natural heat as geothermal energy affect the Earth's core, causing it to cool down? If so, would it result in an ice age? If not, how does the ...
tux's user avatar
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14 votes
1 answer
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What are the causes of the supercontinent cycle?

Throughout geologic history, Earth's continents have broken apart and come together to form supercontinents multiple times, in a somewhat regular period, known as the supercontinent cycle. The length ...
congusbongus's user avatar
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36 votes
3 answers
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Why is Earth's inner core solid?

I have never understood why earth's inner core is solid. Considering that the inner core is made of an iron-nickel alloy (melting point around 1350 C to 1600 C) and the temperature of the inner core ...
tux's user avatar
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20 votes
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What fraction of dry land is below sea level?

Someone just asked me if it would be practical to counter the rise of sea level by pumping water into storage on land. It struck me that if there is enough land below sea level, this would require ...
mwengler's user avatar
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17 votes
2 answers
2k views

At what point does plate tectonics stop?

As the core and mantle of the earth cools, it will reach a point where new crust cannot be produced. How can this point be calculated? If we can, has anyone done such calculations? Thanks!
rnrneverdies's user avatar
16 votes
3 answers
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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, ...
amphibient's user avatar
8 votes
3 answers
1k views

What is the total Earth's interior energy budget?

What is the total Earth's interior energy budget? What is the heat flux per m2 that warms the Earth surface because of the Earthy's internal heat. How much of that heat is replenished from the ...
Irigi's user avatar
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44 votes
6 answers
108k views

Are Richter-magnitude 10 earthquakes possible?

The largest earthquake since 1900 according to the United States Geological Survey (USGS) was Richter-9.5 magnitude quake in Chile in 1960. Are magnitude 10 earthquakes possible? If so, what is the ...
blunders's user avatar
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41 votes
2 answers
8k views

Farthest point from the center of the Earth

At first glance, this seems like such a simple question of "What's the highest point on Earth". However, I also know that the Earth isn't perfectly round. So that "highest point" may be in a ...
Richard's user avatar
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20 votes
3 answers
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How did Earth's plate tectonics start?

Plate tectonics is a theory which describes Earth's lithosphere as being composed of distinct plates which are able to move atop of the underlying asthenosphere. At plate boundaries, this movement ...
Kenshin's user avatar
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1 answer
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Can large (and wet) storms really trigger large magnitude Earthquakes?

At the 2011 AGU Fall meeting, this poster claimed that the water erosion from Taiwan's wettest storms could prematurely trigger large magnitude earthquakes , $ M \ge 6.0 $. If this was true, this ...
Neo's user avatar
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18 votes
1 answer
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How long until Earth's core solidifies?

How much longer does Earth have until the core turns solid? Does global warming change these estimates at all?
user avatar
18 votes
2 answers
874 views

Why is there Uranium in Earth's Crust?

Uranium's density is greater than most elements, so you would expect it to settle to the bottom of a volume of fluid. In the case of the Earth, which was molten in the beginning, you might then expect ...
Cjxcz Odjcayrwl's user avatar
13 votes
3 answers
4k views

Why does Earth's outer-core rotate in the opposite direction to the inner-core?

Is it true that Earth's outercore rotates in the opposite direction to Earth's inner-core? Is there a plausible explanation for why this phenomenon occurs and what is the available evidence ...
Kenshin's user avatar
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11 votes
2 answers
1k views

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 ...
Guillermo Phillips's user avatar
8 votes
1 answer
14k views

Why does the wind periodically change direction?

Image Subtitle: Wind going across the page - and changing direction To clarify, imagine you were sat in a boat in the middle of a lake recording the wind direction every minute. You notice that the ...
Ōkami's user avatar
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-2 votes
1 answer
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Safest spots when an asteroid hits? [closed]

I am breaking this question and no longer making an effort in refining it with the exception of adding an associated link with the scenarios. I always wondered if a devastating asteroid was ...
Muze's user avatar
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48 votes
5 answers
33k views

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?
Kenshin's user avatar
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32 votes
8 answers
3k views

Is earthquake prediction possible?

After the Tohoku and East Coast quakes, I skimmed over several books discussing the validity of earthquake prediction as a discipline, yet found no significant breakthroughs. What should change in our ...
Deer Hunter's user avatar
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30 votes
4 answers
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Why is Earth's outer-core liquid?

The Earth's inner core is solid because despite the enormous temperature in this region, there is also enormous pressure there, which in turn raises the melting point of iron and nickel to a value ...
Kenshin's user avatar
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23 votes
2 answers
500 views

What properties must a rocky body possess in order to exhibit plate tectonics?

The Earth exhibits plate tectonics, but the other terrestrial planets do not (though Mars and Venus may have exhibited plate tectonics in the past). What is "special" about Earth that allows it to ...
senshin's user avatar
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21 votes
2 answers
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Why are minerals found in "large" quantities and not scattered throughout the earth as individual atoms?

Heavier elements are created in stars. After stars die they scatter these heavier elements throughout the universe. These elements eventually gather to form planets. But why do we find "chunks" of ...
Zac Patterson's user avatar
20 votes
2 answers
48k views

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?
Azzie Rogers's user avatar
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20 votes
2 answers
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How does one measure what causes earthquakes?

I know that they occur when energy that was previously stored is released in seismic waves. But how is the energy stored in the earth in the first place, and what can trigger the release of such ...
Tom Au's user avatar
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19 votes
2 answers
17k views

Where is the calmest place on Earth?

I have done some research online, and I've found out that Antarctica has the calmest winds (lowest maximum wind speed) recorded on Earth. However, it is uninhabitable for human life. Other very calm ...
Muze's user avatar
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16 votes
1 answer
3k views

Can impact events cause widespread volcanic activity on the other side of the planet?

The currently accepted theory for P-T mass extinction is environmental change triggered by the Siberian Traps volcanic activity. A paper(1) suggests that the Siberian Traps were caused by a hotspot ...
Gimelist's user avatar
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12 votes
2 answers
1k views

Change in earth mass since the time of the dinosaurs

Is there a significant difference in the mass of the Earth between now and the time of the dinosaurs (250 - 75 million years ago)? I was just wondering if the force of gravity on dinosaurs would have ...
Brian M. Hunt's user avatar
12 votes
3 answers
1k views

How do Rossby Waves in the ocean form?

So on land, I believe that one factor in their formation is due to inhomogeneities in surface heating between land and ocean (and also inhomogeneities in surface heating due to terrain effects like ...
InquilineKea's user avatar
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11 votes
2 answers
16k views

How do I derive the formula for lithostatic (overburden) pressure?

The title pretty much says it. I have the formula: $P = \rho g h$ where $\rho$ is the density, $h$ is how deep the pressure is in the Earth and $g$ is the gravitational acceleration(?). I don't get ...
Tamás's user avatar
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9 votes
1 answer
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What is the current status of geophysical global cooling theory?

Plate tectonics effectively rubbished the theory of geophysical global cooling as a means of explaining many surface features on the Earth. However, this wiki says that the same process is responsible ...
christopherlovell's user avatar
7 votes
5 answers
5k views

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 ...
Florian's user avatar
  • 257
7 votes
2 answers
299 views

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 ...
Brendan's user avatar
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6 votes
3 answers
5k views

Why is the density of Earth higher at the core

If gravitation decreases as we approach the core and if density is a function of gravity we should expect a void core. Unless the accretion disk was formed starting with the objects of highest mass ...
andrei peri's user avatar
4 votes
1 answer
386 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 ...
Adam Bailey's user avatar
2 votes
1 answer
259 views

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 ...
Camilo Rada's user avatar
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36 votes
3 answers
17k views

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?
HingedHD's user avatar
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30 votes
2 answers
23k views

Where on Earth is the magnetic field intensity stronger?

Are there places on Earth that have a strong magnetic field other than the magnetic north and south poles? Can living where (rare) earth magnetic ore is abundant provide a mini-magnetoshere?
Muze's user avatar
  • 1
30 votes
3 answers
45k views

Why is Earth's inner core made of an iron-nickel alloy?

This question has puzzled me for a while. I know that earth's mantle is made of different minerals, metals and rocks etc. and that has always made complete sense to me. But why is the inner core made ...
tux's user avatar
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22 votes
1 answer
77k views

Why are oceanic plates denser than continental plates?

In the theory of tectonic plates, at a convergent boundary between a continental plate and an oceanic plate, the denser plate usually subducts underneath the less dense plate. It is well known that ...
Kenshin's user avatar
  • 7,616
22 votes
12 answers
7k views

How to quickly or easily prove the world is spherical?

A relative of mine has recently introduced me to the modern flat earth theory, which she believes in. Setting aside for the moment that it is ridiculous, and that sending up some balloons with cameras ...
dutch's user avatar
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20 votes
3 answers
4k views

Can the overuse of geothermal energy become an environmental concern? [duplicate]

At what power output would we be using so much geothermal energy that we cool the core enough to endanger the Earth's magnetic field and have to stop using it? Is this a conceivable concern for a ...
Mazura's user avatar
  • 495
20 votes
1 answer
426 views

Why Earth's magnetic poles are (and were) in their positions?

This is a sort of a follow-up question to What causes the Earth to have magnetic poles? The Earth has magnetic fields, and according to dynamo theory I roughly understand why. If the Earth's rotation ...
Pavel V.'s user avatar
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20 votes
4 answers
17k views

Will the Earth ever stop rotating?

It is well known that the Earth's rotation is slowing down and that millions of years ago there was a point in time where there was only a mere 20 hours in a day on Earth. My question is in two parts....
Kenshin's user avatar
  • 7,616
19 votes
2 answers
657 views

To what accuracy and precision do we know the volume of the Earth?

Satellites such as GOCE and GRACE measure the geoid with unprecedented accuracy. Altimeters can determine local surface elevation with millimetre-precision. This makes me wonder: to what precision ...
gerrit's user avatar
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19 votes
4 answers
5k views

What would be the first thing which will render the Earth uninhabitable?

There are quite a few things which can make an otherwise habitable planet uninhabitable, and some of these will eventually happen, sooner or later: engulfed by its star when it becomes a red giant ...
vsz's user avatar
  • 464
18 votes
3 answers
1k views

Why is there a line of volcanoes along the northwest coast of North America?

Mount Hood in Oregon is a dormant volcano, and in Washington Mount St. Helens and Mt. Ranier are both active volcanoes. What causes this line of volcanoes running parallel to the coastline along the ...
Chris Mueller's user avatar
18 votes
0 answers
231 views

How much heat is transported from the interior to the surface in the form of hydration enthalpy?

Heat is transferred from the interior to the surface through several methods. One is simply the conduction of sensible heat through the crust - I would guess this accounts for most of it. But some is ...
N. Virgo's user avatar
  • 1,602
17 votes
2 answers
476 views

What geophysical events can (temporarily) increase the Earth's rate of rotation?

My understanding is that the dominant factor behind the slowing of the Earth's rotation (i.e. the lengthening of the day) is tidal friction induced by the Moon's gravity. As seen on the graph below, ...
senshin's user avatar
  • 1,885
17 votes
2 answers
2k views

What causes the Earth to have magnetic poles?

A compass can tell me the directions of the Earth's North and South poles? What is it about the Earth that produces this "polarity" such that a compass can pick it up? The first thing that jumped ...
Kenshin's user avatar
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