Geophysics

The study of Earth using the combination of Geology and Physics, it lets us understand what is going on under the Earth's surface. Find questions on different types of seismic activities such as earthquakes and volcano eruptions here.

5,632 Questions
Earth Sciences
Geophysics

Where does Earth's water originally come from?

The Short Answer:

Some of it was here when the earth was made (but locked into the rocks as hydrates ... much of that released as the Earth became molten.)

And some came from comets and other ice particles that have bombarded the Earth since it was formed.

No one knows which part was the major contributor.

In more depth...:

At some early point in time (after the moon) the Earth was a hot, glowing ball which would have out-gassed fairly completely. Hydrogen is light enough so that most of it would have escaped. Free Hydrogen is lost from a planet as small as Earth, it takes the outer gas giants with much stronger gravitational pulls to hold it Additionally, there was little or no oxygen (all the bound oxygen was in the rocks - which is mostly still there).

One common theory of where the Earth's water comes from was the comet impact theory. The belief was that earths water came from comets that impacted on the early Earth (recall that at this time there would be no atmosphere to disintegrate the comets). Scientists have looked at samples of ice from comets and the ratios of heavy water (water with an isotope of hydrogen called deuterium) does not match the water found in the oceans. This has lead scientist to believe the oceans are not made up of mostly cometary water.

Evidence of water on the early Earth comes from Zircon Crystals dating from 4.53 billion years ago, only about 200 million years after the planet formed. Zircon crystals can only be created in the presence of water. This has lead scientist to believe that a large percentage of water was already in the rocks on Earth when it was created.

However examination from "fossil water" taken from Hawaiian volcanoes that originally comes from the bottom layers of the crust also shows differences from modern water.

A final note:

The following is a quote from the founder of Ask an Astronomer, Dave Kornreich:

No, H20 cannot exist in stars, but H and O separately can. Hydrogen is the basic building material of the universe, created in the Big Bang. Oxygen is created by nuclear reactions in stars. If you put H and O together in the cold of space, you get H2O. There are enourmous amounts of water in space. In fact, nearly all of the oxygen in space is in the form of water or carbon monoxide. Similarly, most the carbon and nitrogen in space are also in their most hydorgenated forms: methane (CH4) and ammonia (NH3).

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Geophysics
Plate Tectonics

What are answers 1-17 on the plate tectonics crossword puzzle?

1.Thermal Convection2.Tectonics

3.Asthenosphere

4.Subduction

5.Mantle

6.Crust

7.N\A

8.Lithosphere

9.radioactivity

10.Midoceanicridges

11.spreading

12.Trenches

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Earth Sciences
Geophysics
Plate Tectonics

What is the continental drift valley?

The hypothesis that the continents slowly move across Earth's surface.

A2. You are mixing two terms, Continental Drift, and Rift Valley. But both are related.

Continental Drift is as above, where the more-or-less rigid tectonic plates are moved across the Earth's surface by movement of the plastic magma beneath the earth's crust.

Rift Valley. Sometimes these tectonic movements cause a crack to develop in the surface crust, and it splits apart. This is currently happening in Africa, causing the Rift Valley. This is well below sea level, and is HOT, and has many volcanoes. Check out the Afar Depression in Wikipedia.

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Physics
Earth Sciences
Geophysics

What creates Earth's magnetic field?

Scientists think that the presence of the molten nickel iron layer of Earth's outer core and the spinning of the planet creates the magnetic field through the geodynamo mechanism.

The geodynamo mechanism couples the convection of the liquid metal in the Earth's core with the magnetic field to create the current responsible for the magnetic field.

Other planets with a molten metal core can also have a magnetic field.

See related links.


Earth's magnetic field is generated by the electric currents in the conductive material of its core.

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Geology
Geophysics
Rocks and Minerals

Is fluorite a silicate or non-silicate?

Fluorite is a non-silicate mineral.

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Geophysics
Earthquakes

The human effects of muzaffarabad earthquake?

The earthquake of magnitude 7.6 claimed more than 80,000 lives

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Geology
Geophysics

The lithosphere is broken into large sections called?

tectonic plates

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Math and Arithmetic
Geophysics

What will happen in 20 years from now?

You will be 20 years older still waiting for a stupid answer to this dumb assed question. Or dead.

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Drifting
Geophysics
Plate Tectonics

Who propounded the theory of continental drift?

Alfred Wegener

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Earth Sciences
Geophysics

What is the inner core of the Earth made of?

The inner core is made up of both iron and nickel.
The most current science suggests the inner core is nearly pure iron, hot enough to be molten, but because of high pressure it is forced into a metallic state. There are alternate theories (lots of them) but this is the leading current theory.
The most current science suggests the inner core is nearly pure iron, hot enough to be molten, but because of high pressure it is forced into a metallic state. There are alternate theories (lots of them) but this is the leading current theory.

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Earth Sciences
Geophysics
Plate Tectonics

Why wegeners ideas about continental drift were not believe?

His ideas where not generally believed because he was an astronomer and meteorologist. Also scientists believed the earth was shrivelled like an old apple.

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Geophysics
Earthquakes
Plate Tectonics

How do tectonic plates move?

Tectonic plates are segments of the Earth's lithosphere, the hard rocky outer shell composed of the crust and the uppermost mantle. This shell is divided by lines of faults, ridges of plate creation, and zones of plate destruction. All in all, there are roughly 30 tectonic plates which cover the entire surface of the planet. Plates can be composed of oceanic crust, continental crust, or a combination of both.

Plate movements occur because the layer of Earth directly below the lithosphere, the asthenosphere, is hot enough, and under enough lithostatic pressure to prevent its melting, that it can deform without fracture. And although convection of heat does play a role in the movement of lithospheric plates, the convection currents themselves may be caused by gravity, which induces the sinking of older dense slabs of oceanic crust at subduction zones (a process known as 'slab pull').

The energy driving all of these processes is heat from the interior of the Earth derived from radioactive decay and residual heat from Earth's formation, and gravity which results in slab pull and push.

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Geophysics
Earthquakes

Can the US gov create an earthquake?

no. earthquakes are set off by sudden movements in the earths crust

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Geophysics
Earthquakes
Plate Tectonics

What are tectonic plates and how do they move?

Tectonic plates are segments of the Earth's lithosphere, the hard rocky outer shell composed of the crust and the uppermost mantle. This shell is divided by lines of faults, ridges of plate creation, and zones of plate destruction. All in all, there are roughly 30 tectonic plates which cover the entire surface of the planet. Plates can be composed of oceanic crust, continental crust, or a combination of both.

The movement of the plates is caused by the convection currents of heat from the Earth's interior. This heat, rising toward the surface through the mantle causes movement of plastic like rock in the asthenosphere, the layer of Earth directly below the lithosphere. At thinner areas of the crust, such as the mid-ocean ridges, this plastic rock undergoes a transformation, or phase change, into a liquid due to the decrease of lithostatic pressure. The molten rock rises and eventually cools, forming new crust.

At the other end of the convection current, older, cooler oceanic crust is being subducted under less dense crust, falling back into the mantle. The Earth's plates are riding on top of the currents caused by these processes.

The main features of plate tectonics are:

  • The Earth's surface is covered by a series of crustal plates.
  • The plates are composed of crustal rock and solid upper mantle which is called the lithosphere. * Plates are composed of continental and oceanic crust.
  • The oceanic crusts are continually moving, spreading from the center, sinking at the edges, in a process of recycling.
  • Rising legs of convection currents beneath the plates create additional plate material at mid-ocean ridges, sinking legs of convection currents swallow old crustal plates at subduction zones.
  • The heat driving the convection currents is from radioactive decay of material within the Earth and from residual heat from accretion processes during Earth's formation.
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Geology
Geophysics

What is the source of the Earth's internal heat?

The source of the Earth's internal heat is a result of gravitational compression and to a much lesser extent, the decay of radioactive isotopes.

The heat present in the Earth is due to several factors.

The first source of heat is from the remnants of heat from impacts with planetesimals early in Earth's history. Impacts with large bodies such as these (including the impact which led to the formation of the moon) trapped the thermal energy of the collision in the surrounding rock of the planet, and may have been enough in certain circumstances to completely melt the early Earth.

The second source of heat is also a remnant of an early Earth event known as the Iron Catastrophe. With much of early Earth still molten, denser metals, particularly iron and nickel, migrated to the center of the planet. Tremendous amounts of frictional heat was created, enough to completely melt the planet once again.

The third source of heat in the Earth is from compression due to gravity.

The fourth and final source of heat in the Earth is from the decay of radioactive elements. This source of heat is gradually declining due the decreasing amounts of radioactive isotopes, the decrease being caused by the decay.

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Geology
Landforms
Geophysics

Why can't the wind lift and carry large particles?

The particles are to heavy for the air to carry them. I hope this answer your question:)

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Geophysics
Earthquakes

What is the Richter scale and what does it measure?

RICHTER SCALEThe Richter scale (known as the local magnitude scale to seismologists) was originally developed to measure small to moderate magnitude earthquakes in southern California by Charles Richter and Beno Gutenberg. The numerical levels indicate the energy released by a particular quake.

The numerical value is obtained from the logarithm of the maximum amplitude of seismic waves as recorded on a seismometer. This value is then scaled to account for the distance from the epicentre of the earthquake to the seismometer so as to allow the value to be correlated with the local magnitude readings from other seismometers in differing locations (as seismic waves lose their energy as they propagate through the earth so if this correction was not made, then different seismometer stations at different distances would give differing Richter magnitudes for the same earthquake). The Richter magnitude measurement produced by this methodology in theory has no limit and may be positive or negative.

As stated above, the Richter scale itself is a logarithmic mathematical formula which is calibrated so that a ten fold increase in amplitude relates to a single whole number increase on the scale (e.g. an earthquake with a Richter magnitude of 5 has seismic waves with a maximum amplitude 10 times larger than those for a magnitude 4). It has a number of practical limitations, in that it is poor at recording earthquakes with magnitudes greater than 7 and at distances greater than 650 km from a seismometer.

The equation for calculating the Richter magnitude (MR) is shown below:

MR = (Log10A) - (Log10A0)

Where

A = maximum zero to peak amplitude of seismic wave (mm) recorded.

A0 = Empirical function derived from the distance from seismometer station to earthquake epicentre

Log10A0 From 0 to 200 km distance:

Log10A0 = 0.15 - 1.6 log(distance in km)

Between 200 and 600 km distance by:

Log10A0 = 3.38 - 3.0 log(distance in km)

Due to the limitations described above (distance and maximum size of measurable earthquake), it has since been replaced by the Moment Magnitude Scale in the measurement of large earthquakes - for information on this, please see the related question.
the richter scale reads the magnitude of earthquake.

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Science
Geology
Physics
Geophysics

What state of matter is represented by Earth's lithosphere?

Earth's lithosphere, its rigid outer shell, generally represents the solid state of matter.

117118119
Geology
Geophysics

Why is the inner core of the Earth a solid if it is the hottest layer?

The melting point of materials varies depending on the applied pressure. As pressure increases so does the melting temperature. This relationship is normally shown in a phase diagram.

The main constituent of the inner core is iron and the inner core pressure is approximately 330-360 GPA while the temperature varies from approximately 5000 to 7000 K.

The extremely high pressures in the Earth's inner core therefore drive the melting point of the iron up beyond the temperature that occurs and the metals of the inner core cannot melt.

As such the inner core is solid, even though it is the highest temperature region in the Earth.

Please see the related links.

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Geology
Geophysics

What is a group of diamonds called?

A group of diamond is called a cluster

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Geology
Earth Sciences
Geophysics

What is the core of the earth made of?

Outer core - predominantly liquid iron and nickel.

Inner core - predominantly solid iron and nickel.

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Geology
Geophysics

Why is the inner core solid if it is the hottest layer?

The pressures from surrounding material is so intense that despite the high temperatures, the metals of the inner core cannot melt.

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Geophysics
Science Experiments
Rocks and Minerals

Is basalt valuable?

No, there are billions of tons of basalt throughout the world.

117118119
Geology
Geophysics
Plate Tectonics

Why was the continental drift theory or hypothesis rejected at the time that Alfred Wegener proposed it?

Wegener proposed the continental drift theory, and provided scientific evidences for such, but couldn't explain the mechanism or processes behind the movement of continents. It was difficult for anyone to imagine how entire continents might move. It wasn't until the mid-twentieth century with the discovery of the Mid-Atlantic Ridge and sea floor spreading that the processes causing plate movements began to be understood and led to the science of plate tectonics.

Wegener was also a meteorologist and this was not in his field of science, resulting in skepticism by the establishment geologists of his time.

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Geophysics
Oceanography
Coastlines
Tsunamis

What can tsunamis cause?

Tsunamis can cause financial ruin and harm to humans: loss of livestock, loss of loved ones, home loss, job loss, loss of crops and food supplies, leakage of sewage into fresh water sources causing disease, loss of all personal belongings, business losses and other destruction from which many never recover. Other impacts of tsunamis on governments include that many citizens will be homeless, unemployed, hungry, injured, and unable to pay taxes.

Some environmental impact could be: wildfire; injured and killed people, plants and animals; deforestation; damage to coral and marine reefs; destruction of buildings and homes; ruin of businesses; damage to power plants; release of nuclear material from a nuclear power plant; and billions of dollars worth of more destruction.

If you are in the sea when one occurs, the most you will feel is a bump, like a large underwater wave. Tsunami waves can move right under large vessels on the water without notice until the wave reaches the more shallow waters near shore where they can rise as much as hundreds of feet above sea level.

Once it hits land, then the chaos occurs.

The first wave is slow moving, going crawling on the floor of the sea bed. The next wave rides on the first, moving fast and with a very large volume. These enormous waves cause death and destruction on islands or coastal areas.

It causes damage and floods.

When a tsunami wave comes ashore, it can affect a huge area of land, transforming the landscape. First, a tsunami wave throws salty seawater over the land. Too much salt is bad for living things, so if soil becomes too salty, crops cannot grow or will not grow well. In addition, the force of a tsunami can ruin pipelines and factories. This lets out sewage, oil, or dangerous chemicals into the environment. It can take many years for the environment to revert to normal.

A tsumani affects the Earth by killing or damaging everything in its destructive path. Plants and animals are hurt if they do not sense the pending tsunami and leave the area before it hits.

More:

Tsunamis will definitely cause casualties and injuries. Tsunamis, as they originate from the sea or another large body of water, will wash fishing boats and other boats anchored close to the shore (such as cruise ships) onto shore and sometimes deep inland. The boats will be stuck on shore and usually wrecked from the forces of the event.

The tsunami will also cause fish and marine life to be washed onto shore and trapped there to die.

They can also flood the lands near the shore, causing people to die from them. They will damage the crops and cause nearby buildings to collapse. Some people might be trapped under the buildings and die. They uproot trees too, causing them to fall on houses and people.

Lastly, they cause economic decline as the people and governments have to spend a lot of money rebuilding the houses and restoring the original landscape. This can be extremely costly, especially if it is a beautiful resort area. They would also have to compensate the victims' families as a form of comforting. They would also face a decrease in tourism.

Due to the damages and loss of life, tsunamis can also cause despair problems to survivors and witnesses of the tsunami, including relatives of the victims. This problem is a most serious one, as it is very difficult to cure and it takes a very long time.

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