What’s the most recent eruption of Vesuvius and will it erupt again?

 

Photo by Italian Air Force from Green and Short (1971).
Vesuvius has erupted about three dozen times since 79 A.D., most recently from 1913-1944. The 1913-1944 eruption is thought to be the end of an eruptive cycle that began in 1631. It has not erupted since then, but Vesuvius is an active volcano, it will erupt again.
The [...]

Why are there so many volcanoes in the Pacific Northwest and Alaska?

 
The distribution of volcanoes in the northwest and Alaska is the result of plate tectonics. In the northwest, the oceanic Farallon Plate is being pushed beneath (subducted) the continental margin of the North American Plate. When the subducted plate comes in contact with the hot asthenosphere beneath the continental plate conditions are right for the [...]

How do volcanoes affect the atmosphere and climate?

This photo shows the large white billowing eruption plume from Rabaul being carried in a westerly direction by the weak prevailing winds. At the base of the eruption column is a layer of yellow-brown ash being distributed by lower level winds. A sharp boundary moving outward from the center of the eruption in the lower [...]

How does a thermocouple measure the temperature of lava without melting?

A thermocouple works on the principle that the electrical resistance at the point where two wires of different composition join, is very sensitive to the temperature. So…a thermocouple consists of two wires joined to an electrical source. Current passes through the wires and they only touch eachother out at the tip of the thermocouple probe. [...]

How do volcanoes help scientists learn about the Earth’s interior?

The deepest samples of the Earth’s interior brought up from drill holes come from a depth of 12 km . . . . volcanoes provide direct samples of the Earth’s interior from much greater depths . . at least 100 km, and, perhaps, as deep as the core-mantle boundary.
John Dvorak

How do Volcanologists predict volcanic eruptions?

The prediction of volcanic eruptions is difficult because, to be of practical use, they must be made before eruptions! Its a lot easier to see patterns in monitoring data after an eruption has occurred. But great progress has been made because of the lessons learned over many years at Kilauea volcano in Hawaii, and applied [...]

What tools do Volcanologists use to study volcanoes?

Photograph of a tiltmeter courtesy of U.S. Geological Survey.
Volcanologists use many different kinds of tools including instruments that detect and record earthquakes (seismometers and seimographs), instruments that measure ground deformation (EDM, Leveling, GPS, tilt), instruments that detect and measure volcanic gases (COSPEC), instruments that determine how much lava is moving underground (VLF, EM-31), video and [...]

What makes the magma come out of the chamber and how does magma form?

Magma forms from partial melting of mantle rocks. As the rocks move upward (or have water added to them), they start to melt a little bit. These little blebs of melt migrate upward and coalesce into larger volumes that continue to move upward. They may collect in a magma chamber or they may just come [...]

Why is lava so hot?

Lava is hot for two reasons:

It’s hot deep in the Earth (about 100 km down) where rocks melt to make magma.
The rock around the magma is a good insulator, so the magma doesn’t lose much heat on the way to the surface.

Steve Mattox

Why is lava different colors?

The color of lava depends on its temperature. It starts out bright orange (1000-1150 C). As it cools the color changes to bright red (800-1000 C), then do dark red (650-800 C), and to brownish red (500-650 C). Solid lava is black (but can still be very hot).
Steve Mattox