Questions tagged [volcanology]

The properties and behaviour of volcanoes.

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3
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1answer
787 views

how high was mount vesuvius (mount somma?) before it erupted in AD 79?

I guess the highest point of the Mount Vesuvius / Mount Somma complex is currently 1,281 metres (4,203 feet). My question is: how tall was it before it erupted in AD 79?
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1answer
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Why do human populations concentrate near fault lines, volcanoes, etc.?

I've noticed that many places with large populations tend to be prime zones for natural disaster. Examples: Silicon Valley = earthquakes, Houston = hurricanes and floods, Japan = tsunamis and ...
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1answer
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What is likely to have happened with these newly discovered antarctic volcanos below the ice?

The Guardian article Scientists discover 91 volcanoes below Antarctic ice sheet highlights a recently published University of Edinburgh School of Geosciences discovery and cataloging of over ninety ...
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2answers
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Volcanoes and Lightning [duplicate]

Just wondering about this question has been popped into my head many times and as what I have seen in some volcanic activities that when a volcano erupts there's a lightning, & i don't know if ...
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2answers
358 views

Water and explosive volcanoes in the Pacific ring of fire

Most volcanoes in the Pacific Ring of Fire have an explosive nature. This is due to high concentrations of water in their magma. Obviously, this magma comes from several kilometres below the earth's ...
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3answers
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Do volcanos really create fertile soil?

I'm developing an ecology for a portion of my world that's geologically active and I remembered hearing that volcanic ash in soil makes it more fertile to agriculture. After extensive googling I've ...
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0answers
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What happens to the earth after volcanism/tectonics slows?

If we move far enough into the future that the core begins to solidify to the point that volcanism and tectonics are non-existent, what does the surface of the planet begin to look like? Does the ...
9
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1answer
613 views

How are data from tiltmeters used to monitor volcanic activity?

I've just learned in this answer that tiltmeters (which I assume measure changes in tilt) are used near active volcanos. (Saw a mention in item 4. here also.) What kind of geological (volcanological?)...
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1answer
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What drove the Puy de Dôme volcano?

The Puy de Dôme is an extinct volcano located pretty much smack in the middle of France. It last erupted some seven thousand years ago, which in geological terms is fairly recent - prehistoric humans ...
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1answer
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A circle shape in Madagascar

I was seeing Madagascar on Google Maps and accidentally i saw a circle shape near Bebao. Coordinates are 17.4317443°E and 44.644248°S. Please, to satisfy my curiosity, can you tell me why is this ...
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2answers
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Why did it take so long to discover the volcanic nature of mid-oceanic ridges?

I just read this article and was astonished to see the following: Oceanographers stumbled on [the mid-oceanic ridges'] volcanic nature in 1973. What I find surprising is how recent that is. ...
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2answers
690 views

What would happen if magma flows into a very large oil deposit?

If there were an earthquake that somehow cause a crack in the earth and allowed a significant amount of magma to flow into a very large oil deposit. With that high amount of explosive energy that ...
5
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1answer
154 views

Is the momentum of a volcano's high-velocity ejecta mostly due to expanding gas?

When I was very young I was always amazed that water didn't come shooting up out of the first ice-fishing hole of the season, due to the weight of all the ice. It doesn't, because the weight of the ...
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1answer
73 views

What causes lava eruptions (and shutoffs)?

I understand the process of volcanism and the reason for magma deposition on the surface of the earth. What is not clear to me, or what seems to be less well explained is why eruptions occur and then ...
5
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1answer
163 views

Yellowstone Eruption Possibility?

What is the probability of the Yellowstone supervolcano erupting during any given year? I had heard that it erupts once every 100,000 years. Does that mean there is a .001% chance of it erupting ...
4
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1answer
913 views

The position of magma chambers

Where do magma chambers exist? Is it necessary that they exist in the asthenosphere where the circumstances of temperature and pressure are suitable for the rocks to be molten? Or they exist in places ...
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0answers
219 views

What is solidus and liquidus temperature of granite?

My understanding is that because a rock is composed of variety of minerals, so it does not have fix melting point, rather there is a range below which whole rock is solid and above which whole rock is ...
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1answer
192 views

If lava flows back into the ground, would it be called magma?

If lava flows back into the ground, would it be called magma again? Is there a difference if it flowed into a new hole vs the flow it came from?
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1answer
160 views

Are the other causes of an earthquake (e.g. volcanic eruptions) the cause of the “sudden slip” which is the main cause of an earthquake?

I am to deliver an informative speech about earthquakes in class. However, I was not the first to talk about earthquakes and his discussion of the cause of earthquakes is different from mine. He ...
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1answer
147 views

Is there a 'standard size' for volcanic eruptions in terms of gas output?

We saw recently the Iceland volcano Eyjafjallajökull produced significant gaseous output that impacted the flight paths of several planes. When we look at volcanic gas components, we see they ...
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2answers
184 views

Does the size of Earth increase due to volcanism?

In a volcanic eruption, magma rushes to the 'outside' of the Earth. Does this mean the size of Earth also increases? If not, how is the volume left after the magma rushed out refilled?
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1answer
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Lava and Magma, Meteor and Meteorite--What's the Difference?

Some features of Earth (and beyond) have been bugging me for quite some time. When molten rock is beneath the surface, it's called "magma". Above the surface, it is called "lava". When a bolide is ...
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1answer
182 views

If I can drill a hole to mantle, does it form a volcano?

Suppose if I can drill a hole to mantle at arbitrary point of crust, will magma start rise from the hole and finally become a volcano?
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3answers
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Is the term “fertile ash” a misnomer?

I understand that volcanic ash contains minerals and can make soil more fertile. But I've also heard the term "fertile ash" in some documentary (I have forgotten in what context). Is that a ...
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Basalt vs. columnar basalt

I recently visited a cliff on the south coast of Ulva in the Inner Hebrides where there are ~10m thick flows of columnar basalt. The columnar basalt forming most of the cliff is sandwiched between ...
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3answers
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Can human activity affect volcanoes?

As part of a course on Natural Disasters, I have a group presentation in which we focus on a specific natural disaster. One of the questions we have to address is how human activity may have affected ...
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0answers
242 views

How big a risk is Mount Vesuvius for the local population?

How much of a risk does Mount Vesuvius pose for the population of the surrounding area?
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343 views

Do lava lakes exist in all volcanoes initially?

I know persistent lava lakes are rare, but do they occur in all volcanoes originally, and just not persist over time?
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525 views

Can we see lava in a divergent tectonic boundary?

Can we actually see an orange line of lava if we look down to the crack of the divergent boundary of tectonic plates?
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2answers
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What is the source of lava of volcano? From magma below crust? Or from molten crust by rubbing?

Ok, it looks like a very simple question but I still have some point want to clarify... Most images explain volcanos contain some orange stuffs as magma below volcanoes as magma chamber, but the ...
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1answer
120 views

Do discordants dykes ever travel concordantly (are transgressive dykes a thing)?

Transgressive sills "jump" between bedding planes, following joints: ...
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Earthquake severity during supereruption at Yellowstone caldera?

Theoretically, I ponder what type and strength a supereruption would generate, say for example at the Yellowstone caldera? The last supereruption was roughly 70,000 years ago when Toba erupted. It's ...
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4answers
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Can we reduce the scale of volcanic eruptions by drilling some canals or bombing some holes in the crater?

As we know, when large scale volcanic eruptions occurs, large amounts of ashes and lava rushed out at short time, is it possible to drill some canels or bomb some holes in the crater so that the gas ...
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1answer
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Volcano magma chamber [duplicate]

If I use a really big drill and drill all the way down to a magma chamber what exactly would happen? From what I understand we cant drill to a Magma Chamber because it is really hot, but I have a ...
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1answer
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How long would it take for Mars to cool after asteroid impact? [closed]

As someone interested in terraforming, the main obstacle to colonizing Mars is the lack of a magnetosphere and Atmosphere. To create a magnetosphere of sufficient magnitude the Martian core must be ...
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1answer
602 views

Are volcanoes formed from earthquakes?

I know that some earthquakes are caused by volcanoes and that some earthquakes can trigger volcanic eruptions close to where the earthquake is. But what if a great earthquake(8.0 or above) occurs and ...
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1answer
528 views

Does flow banding only occur in silicic rocks?

I made a video about what I learnt in my A Level Geology course so far, about igneous rocks. One thing I mentioned was that flow banding is mostly only found in silicic rocks (and so mostly rhyolite) ...
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3answers
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Why doesn't the whole volcanic cone appear black?

Cooled lava looks black, but why the whole volcano, even near crater, doesn't always appear black like cooled lava?
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2answers
603 views

Volcanoes in the Great Barrier Reef

Was there ever at any point in time a volcano in the great barrier reef? I thought atolls develop from volcanic islands, and the coral grow around them.
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1answer
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Do the rocks below an active sill go down, or those above go up, or both?

Having read a little about sill formations like the Palisades Sill (eastern USA) and Whin Sill (UK), I understand that strata became separated by the injected layer of magma, with monumental ...
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2answers
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Are Pompeii and Herculaneum unique?

Has anyone ever found or gone looking for similar locations, i.e. volcanic eruption sites in which unfortunate victims – human and non-human – have been entombed in the volcanic ash, with the ...
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1answer
111 views

Do higher global temperatures increase volcanic activity and earthquakes?

I've read that when global temperature increases significantly, liquid magma can make it's way closer to the surface of earth, causing increased volcanic activity and earthquakes. Is there scientific ...
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3answers
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Can volcanos change the climate?

I have heard politicians claiming that volcanoes are the sole cause of global warming and using so called "NASA data" to show that the Earth is actually cooling instead of warming. While the nature ...
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1answer
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Difference between the oxygen/$CO_2$ ratio during the period of the dinosaurs and the present

Here's the base of my question: Was volcanic activity more prevalent when the dinosaurs roamed? Is it true that during the time of the dinosaurs, both the oxygen requirements (by all living creatures ...
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2answers
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Red volcanic soils - what are the likely constituents?

I live very near an extinct Andesite volcano and hiking in that area I've noticed bands of soil that have a dark red coloration. I've also been in Kauai, one of the volcanic islands of Hawaii, but ...
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Is the magma in one volcano different from the magma in every other volcano?

First off, a confession: I'm asking this question because of The Lord of the Rings. If you're not aware already, in the story, a magical ring can only be destroyed in a specific volcano. The reason ...
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2answers
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Can volcanos cause isostatic depression

Isostatic depression is normally associated with glaciation, but can other geologic processes result in similar behavior of the lithosphere? Especially, can the weight of a volcano cause the ...
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5answers
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Why does New Zealand and cold countries have volcanoes?

I understand that volcanoes are caused by the heat that causes high intense pressure below the Earth's surface. This intense pressure gets released and causes magna which becomes hot lava to flow out ...
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2answers
816 views

What processes produced the basalt columns of the Giant's Causeway?

The Giant's Causeway is, according to the Wikipedia page was formed during during the Paleogene Period, Antrim was subject to intense volcanic activity, when highly fluid molten basalt intruded ...
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1answer
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Is this article self-contradictory, or am I missing something?

This article: Anderson, C. H., C. J. Behrens, G. A. Floyd, and M. R. Vining. 1998. “Crater Firn Caves of Mount St. Helens, Washington.” Journal of Cave and Karst Studies 60: 44–50. discusses, among ...