street entertainers face the free-rider probl
Examples of free-rider problem It is good to reduce ou...
A magma with a lot of dissolved gases will form a lot of large bubbles. It is the bursting of these bubbles that causes an eruption to be explosive, so the more volatiles in the magma, the more violent the eruption.
A volcano’s explosiveness depends on the composition of the magma (molten rock) and how readily gas can escape from it. As magma rises and pressure is released, gas bubbles (mainly of water vapor and carbon dioxide) form and expand rapidly, causing explosions.
On land, volcanoes form when one tectonic plate moves under another. Usually a thin, heavy oceanic plate subducts, or moves under, a thicker continental plate. … When enough magma builds up in the magma chamber, it forces its way up to the surface and erupts, often causing volcanic eruptions.
Major health threats from a volcanic eruption
Health concerns after a volcanic eruption include infectious disease, respiratory illness, burns, injuries from falls, and vehicle accidents related to the slippery, hazy conditions caused by ash.
Volcanoes are formed when magma from within the Earth’s upper mantle works its way to the surface. At the surface, it erupts to form lava flows and ash deposits. Over time as the volcano continues to erupt, it will get bigger and bigger.
Livestock and other mammals have been killed by lava flows, pyroclastic flows, tephra falls, atmospheric effects, gases, and tsunami. They can also die from famine, forest fires, and earthquakes caused by or related to eruptions. … Eruptions can influence bird migration, roosting, flying ability, and feeding activity.
“Black smokers” are chimneys formed from deposits of iron sulfide, which is black. “White smokers” are chimneys formed from deposits of barium, calcium, and silicon, which are white. Underwater volcanoes at spreading ridges and convergent plate boundaries produce hot springs known as hydrothermal vents.
The secondary hazards are the indirect consequences such as lahars, tsunamis and epidemic disease and post-eruption famine. During eruptions, volcanoes release a huge amount of pyroclastic rocks or tephra into the atmosphere and these clastic deposits will fall back and accumulate on the surrounding Earth’s surface.
Which volcanic eruptions were the deadliest?
|Unzendake, Japan||1792||Volcano collapse, Tsunami2|
|Lakagigar (Laki), Iceland||1783||Starvation2|
The largest and most violent of all the types of volcanic eruptions are Plinian eruptions. They are caused by the fragmentation of gassy magma, and are usually associated with very viscous magmas (dacite and rhyolite).
the primary factors that determine whether a volcano erupts explosively or quietly include characteristics of the magma and the amount of dissolved gases in the magma.
Stratovolcanoes are considered the most violent. Mount St. Helens, in Washington state, is a stratovolcano that erupted on May 18, 1980.
Explosive eruptions are favored by high gas content & high viscosity magmas (andesitic to rhyolitic magmas). The explosive bursting of bubbles fragments the magma into clots of liquid that cool as they fall through the air.
Although there are several factors triggering a volcanic eruption, three predominate: the buoyancy of the magma, the pressure from the exsolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber. What follows is a brief description of these processes.
A periodic weak to violent eruption characterized by fountain lava. … A steam-driven eruption as the hot rocks come in contact with water. Phreatomagmatic. Is a violent eruption due to the contact between water and magma.
Thick lava, for example acid lava, has the potential to cause much larger and more explosive eruptions, therefore presenting a larger threat and increased potential for hazardous activity. The location of a volcano is also a large variable in determining the nature of its eruptions.
geo quiz 6