49 votes
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Why is Olympus Mons the largest volcano in the whole solar system?

This is mostly due to the fact that Mars does not have plate tectonics. Therefore the plate stays above the hotspot without moving, allowing magma to rise and pile up at the same place for millions ...
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28 votes

Where can obsidian be found?

The processes forming obsidian are not well understood because an active obsidian-forming eruption has never been recorded by humans. However, we can make many inferences from the composition of the ...
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  • 2,563
27 votes
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Why don't scientists use fire entry suits to study volcanoes?

I'm a volcanologist and I have worked on erupting volcanoes. First of all, volcanologists almost never actually wear those suits. Heat is almost never the hazard that matters in the situations in ...
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  • 2,563
21 votes

Do volcanos really create fertile soil?

As always: It Depends. Assuming enough water and sunshine, crop growth rate boils down to the concept of limiting nutrients. These may be: nitrogen (via ammonia or nitrates), phosphorous (via ...
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21 votes

If the Bennu asteroid were to hit within a 500 mile radius of Yellowstone National Park, will it trigger a super volcano at Yellowstone?

There is actually an hypothesis that large asteroid impacts can trigger volcanism at the antipodal point, where the seismic energy of the impact focuses. On Earth, it has been suggested that the ...
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20 votes
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Why is there a line of volcanoes along the northwest coast of North America?

The Cascades (the volcanic range that Mt. St. Helens and Mt. Ranier are a part of) are "arc volcanoes" (a.k.a. "a volcanic arc", etc). Volcanic arcs form at a regular distance (and fairly regular ...
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20 votes
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What are some of the strongest theories against the existence of mantle plumes?

The best argument I've heard supporting strong skepticism of plumes, if not total dismissal, is that the theory is too flexible. To put it more bluntly, this amounts to saying that it is unfalsifiable ...
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19 votes
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What percent of volcanoes are glaciated?

21.7%, by my calculations (338 / 1556 holocene-active volcanoes). I calculated perennial snow by combining 6 weeks of MOD10A2 data from winter and summer weeks in 2014 to figure out which pixels had ...
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  • 2,563
18 votes
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Where can obsidian be found?

Obsidian is formed when a rhyolitic (or felsic) lava flows cool rapidly. This must mean that it's mostly available on the surface (and I think if you go near volcanos you can find pieces of Obsidian ...
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17 votes
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If the Bennu asteroid were to hit within a 500 mile radius of Yellowstone National Park, will it trigger a super volcano at Yellowstone?

Maybe but it will depend on the state of the magma chamber under the caldera. If the magma chamber is already under enough pressure and has a super-eruptive quantity of liquid melt in it then the ...
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  • 4,227
16 votes
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Does volcanic activity fluctuate?

This is probably an observational effect that is quite common in the Earth Sciences. In scientifically progressing societies there is a higher proportion of observations due to a number of effects: ...
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  • 3,876
16 votes
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Why won't Yellowstone explode?

This is a complex question, and I cannot give you a complete answer I'd like to point out that there is a very important article published in February of this year on the subject: volcanoes are in an ...
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  • 6,356
16 votes

Is the magma in one volcano different from the magma in every other volcano?

In keeping with your Lord of the Rings inspiration, the first reference is from New Zealand, where the Lord of the Rings movies were made. There are three main types of magma that volcanoes currently ...
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16 votes
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How did CO₂ originate on Earth before there was life?

The answer is Volcanos. There might be other inorganic processes capable to produce $\text{CO}_2$, but on Earth, the main inorganic source of $\text{CO}_2$ are volcanoes. In some period of Earth's ...
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15 votes
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Zeolites, odor control, and the witchcraft of sunlight

Zeolites are very similar to clays, with one key difference. The molecular structure of clays is rather compact. In contrast, the molecular structure of zeolites has tiny molecular-sized holes, and ...
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  • 20.2k
15 votes

Why does New Zealand and cold countries have volcanoes?

Surface temperatures on Earth are a consequence of solar heating and radiative cooling - in other words, the heat energy which drives climate comes from sunlight falling on the Earth "now". On the ...
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  • 439
14 votes
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What causes a volcano?

Most volcanism occurs at three major tectonic features: Subduction Zones, Rifting Centers (Like East Pacific Rise) and under hotspots. I will start with the most contentious, hotspots. The clearest ...
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  • 6,356
14 votes
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Why do human populations concentrate near fault lines, volcanoes, etc.?

You're asking Why do human populations concentrate near fault lines, volcanoes, etc.? But the real question is Do human populations concentrate near fault lines, volcanoes, etc.? And the ...
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14 votes
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Why are the latest additions to the Hawaiian-Emperor seamount chain the highest?

As it was explained to me at university there are two factors; buoyancy and erosion. Rock buoyancy is a major factor, fresh Basalt is hot and dry and has a much lower density than older oceanic ...
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13 votes

Does volcanic activity fluctuate?

Whether volcanic activity fluctuates depends rather on the timescales you are looking at. Crisp (1984) compiles available data on igneous activity lasting for longer than 300 years and concludes that ...
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13 votes

Why do some earthquakes and volcanoes occur within plates?

Crustal plates are not homogeneous, uniformly continuous rock masses with uniform stresses. They are a mixture of rock types with variable stresses and stress concentrations. They are also ...
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13 votes

What gases are in the vesicles of pumice?

Pumice does not contain any gas, the vesicles are empty1. The magma which generated the pumice used to contain gas, mostly water and CO2 like you said. But this gas was lost during the eruption. Most ...
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13 votes
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If people aim to reach the mantle, why don't they just use volcano craters?

why don't they just use volcano craters? Because volcano craters don't go to the mantle. Here's a sketch of how the crust, mantle, and volcanoes look like: Tan colour is crust, orange is mantle. ...
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13 votes

Why are there no volcanoes where continents collide with each other?

Or is the continental crust too dry? Exactly this. Continental collision zones are actually full of volcanic rocks, which formed at the time before it was a continental collision zone. The Wikipedia ...
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12 votes
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Is the Yellowstone National Park unique for its geysers?

Yellowstone is thought to be above a mantle plume, of with there are tens to hundreds on our planet, although there is plenty of debate on this matter. The exact nature of mantle plumes is a huge area ...
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12 votes
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Why did the Laki eruption of 1783 produce so much fluorine?

First things first about Laki: it's in Iceland, which means its source is a combination of an ocean ridge and a mantle plume. The plume contribution means that the source composition is relatively ...
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12 votes

Where can obsidian be found?

I have seen it on the surface in some the lava fields of Iceland. This is consistent with @Neo answer. Obsidian is not that often present, but if present, there is usually plenty around. It occurs in ...
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