27 votes
Accepted

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 ...
  • 2,573
22 votes
Accepted

Can living where (rare) earth magnetic ore is abundant provide any protection from cosmic radiation?

Absolutely not. First of all, "rare earth magnet ore", meaning the ores of metals like neodymium (Nd) and samarium (Sm), is not magnetic at all. It only becomes a magnet once you make a ...
  • 22.3k
14 votes

Can a cosmic impact break Earth's crust in large area exposing the magma ocean?

Let me first correct a small misconception. Where you are talking about 'the magma ocean', you are implying that one exists. This is in fact false. There is no 'magma ocean' in the Earth at the moment ...
  • 22.3k
11 votes

Can living where (rare) earth magnetic ore is abundant provide any protection from cosmic radiation?

No. Cosmic radiation are high-energy particles that create particle showers high up in the terrestrial atmosphere. Those particle shower are heavily beamed downwards, and although in principle some ...
11 votes

Why don't scientists use fire entry suits to study volcanoes?

I think the answer to "Why don't scientists use fire entry suits to study volcanoes?" is that this is a question of professional ethics rather than of technology. For some institution to support, ...
  • 3,780
9 votes
Accepted

Does Magnetic Deviation depend on altitude?

Technically yes, but practically, usually no. The magnetic field varies in three dimensions and the variations are not parallel to the Earth's surface. However, horizontal distances varies usually ...
  • 5,906
8 votes
Accepted

Is there an earth science discipline, or subdiscipline, that only studies magma or lava?

Perhaps they are called Igneous Petrologists ? Someone who studies magma/lava flows tends to go by Geophysicist because they inherently study continuum mechanics and fluid flow.
  • 6,386
8 votes
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What are rare earths and why do they cluster near alkaline magmatism?

What are the rare earths? The rare earths are a group of several elements. The widest definition includes the 15 lanthanides: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and two ...
  • 22.3k
7 votes

Why are alkali basalts found at rifting centres and on top of 'plumes', whereas MORBs are generally tholeiitic?

Geology/Petrology has proposed some models for the origin of basalts which are based upon chemical evidence from rocks. Modern origin-models have been constrained by isotopic chemistry for some time. ...
  • 3,780
6 votes
Accepted

Why are alkali basalts found at rifting centres and on top of 'plumes', whereas MORBs are generally tholeiitic?

Short answer Na and K are incompatible in the mantle. Low degree melting that occurs deep in the mantle forms magmas enriched in Na and K. Magmas formed due to hot spots are formed deep in the mantle....
  • 22.3k
5 votes

Why do (some) silicic bodies behave effusively instead behaving explosively as in common?

To complete Gimelist's answer: many silicic domes and flows lie right on top of a tephra layer with the same age and composition. See for instance this classic paper of Fink (1980) about Little Glass ...
5 votes
Accepted

Why do (some) silicic bodies behave effusively instead behaving explosively as in common?

Explosive volcanic events happen mostly because of saturation in gases, and increase in pressure above the strength of the top of the magma chamber. As the magma decompresses or cools, H2O (mostly), ...
  • 22.3k
4 votes

Why is ignimbrite associated with felsic magmas?

Felsic magmas contain much more silica (SiO2) than mafic magmas (almost by definition). The excess silica chains cause the magma to be much more viscous and therefore more prone to explosive eruptions ...
  • 947
4 votes
Accepted

Relative dating of intrusion

It does seem like it's impossible to know unless you have additional information. However, I think there is a hint in there. See this white halo around the intrusion? My guess (and I could be wrong ...
  • 22.3k
4 votes
Accepted

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

Yes, they are. It's not the sills or dykes that "jump", it's the magma. Depending on the various parameters such as viscosity, stress, temperature, pressure, and local conditions and availability of ...
  • 22.3k
4 votes
Accepted

What is the difference between subvolcanic rocks and plutonic rocks?

Main difference between a subvolcanic verses a plutonic is depth at which the rock solidified at from its molten state. Plutonic implies a depth greater than subvolcanic by definition but I am sure ...
4 votes
Accepted

What is the difference between a depleted mantle, and a fertile or enriched mantle?

Basically, a fertile mantle is a portion of mantle that has not experienced any melting. On the other hand, a depleted mantle has experienced partial melting, and subsequent extraction of this melt. ...
3 votes

How does one get a steep-sided stratovolcano with extremely fluid, low-viscosity lava?

Volcano Café just published a series of articles about Nyiragongo, with one part answering this very question: "Steep slopes despite very fluid lavas. How Nyiragongo got it shape". (It is ...
3 votes

Why the "Mission to Earth’s core" proposal suggests using liquid iron instead of lead?

I've already commented on this before here. This will not work regardless of whether this is iron or lead or anything else. The fact that it was published in Nature does not mean it is true, always ...
  • 22.3k
3 votes

Melting basalt on the lunar surface - what would the resulting material be like?

Melting lunar dust of basaltic composition will result (unsurprisingly) in basalt lava. There might be some volatile loss - if for some reason the basalt had some H2O or CO2 trapped in the solid you ...
  • 22.3k
3 votes

Why don't scientists use fire entry suits to study volcanoes?

Main danger to life near a volcano is not heat from the lava but volcanic gases. Volcanic gases are typically very acidic, poisonous gases and can displace breathable air near lava flows. http://...
2 votes

Volcano magma chamber

You might get a lava seepage, but I doubt it. The cross-sectional area of a borehole is small compared to the total cross sectional area of fractures that are there already. Note that volcanoes bulge ...
2 votes
Accepted

Do the rocks below an active sill go down, or those above go up, or both?

It's both. The rocks above the sill go up, whereas those below it go down. For shallow diking events it's mostly up. This is all based on theory of linear elasticity. People model deformation using ...
  • 2,361
2 votes

Cooling time of basalt flows?

Of course there is, and in not that complex. Is called the heat equation, and is a type of diffusion equation that can be easily solved numerically or analytically in some simple geometries. If you ...
  • 17.1k
2 votes

Can living where (rare) earth magnetic ore is abundant provide any protection from cosmic radiation?

Magnetite is a type of iron ore and does not significantly affect the Earth's magnetic field. It would not protect you from cosmic radiation. However, cosmic radiation is more intense high in the ...
2 votes
Accepted

Heating and cooling a non-magnetic iron ore causes it to become magnetic?

What's happening is called induced magnetism, detailed in a variety of places, including this paper by Kostadinova-Avramova and Kovacheva in Geophysical Journal International: It is well ...
  • 3,144
2 votes

Why does the loss of water from a felsic magma encourage crystallisation?

This answer is based on Winter's presentation for his textbook. Look up chapter 7 on his website, and start at slide 39. First let's go through some of your statements: Felsic magmas crystallise ...
  • 22.3k
2 votes

Can living where (rare) earth magnetic ore is abundant provide any protection from cosmic radiation?

The magnetic field stops the charged particles mostly by trapping them along their fields lines (globally parallel to the ground at most latitudes, plunging to the ground near the poles (therefore ...
  • 21
2 votes

Can living where (rare) earth magnetic ore is abundant provide any protection from cosmic radiation?

Although the other answers have correctly pointed out that this isn't a relevant thing on Earth, it should be mentioned that such an effect does occur on the Moon: it is the likely cause for the Lunar ...

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