VOLCANOES
marlo fosco
Volcanoes are openings, or vents where lava, tephra (small rocks), and steam erupt on to the Earth's surface.
They form along boundaries where rock is heated and turned into magma, where it builds up a pocket. Sometimes the magma continues flowing and creates a hotspot, a place where a magma pocket remains and creates volcanoes even if the plate has moved.
They form from series of cracks within and beneath the volcano, and a vent connects to one or more linked storage areas of molten or partially molten rock (magma).
Magma Types
Basalt: The first type of this liquid is basalt and it is very low in silica and has a very low gas content as well. In addition, this liquid has a low viscosity, meaning that it appears thicker.
Andesite: Andesite magma occurs at a slightly lower temperature than basalt, ranging from 800 to 1,000 degrees Celsius. It also has a slightly higher content of silica and gas and is moderately viscous compared to the low viscosity of basalt liquid rock.
Rhyolite: The third type of magma is rhyolite and it occurs at the lowest temperature possible for this substance, ranging from 750 to 850 degrees Celsius. It is the complete opposite of the basalt version as it is rich in silica and has high gas content. In addition, it has a high viscosity.
Cinder Cone: Small pieces of solid lava, called cinder, that are erupted from a vent. They look like cones with an opening at the top.The eruption is where gas-filled magma bursts out of the peak and is thrown around.
Composite Volcano(Stratovolcano):They are usually tall with steep even sides and are made out of repeating layers of lava flows, volcanic ash, cinders, blocks, and volcanic bombs.
The eruption of these kinds of volcanoes is the most violent, high-viscosity magma explodes out of the top and solidifies after landing.
Shield Volcano: Shield volcanoes are built almost entirely of fluid lava flows. Lava pours out of vents in all directions, either from the top (summit) or along to three rift zones (fractures) that radiate out from the summit in long strands.Eruptions of these volcanoes have low-viscosity magma that builds up the volcano itself.
Caldera: They form when a large magma chamber is emptied by a volcanic eruption or by subsurface magma movement. It looks like a giant crater or valley. These are not volcanoes, but are a result of one. These form after a stratovolcano has an eruption.
High viscosity andesitic or rhyolitic magma blocks the hole that magma flows out of and it builds up, after a while the pressure gets to be too much and it explodes.
Active, Dormant, and Extinct Volcanoes
Active volcanoes:Volcanoes that have erupted at least once in the last 10,000 years.
Dormant volcanoes: Volcanoes that haven’t erupted in at least 10,000 years, but are expected to.
Extinct volcanoes: Volcanoes that haven’t erupted in at least 10,000 years and are not expected to at all.
Lava flows: is where lava runs along the sides of a volcano and reaches down to the bottom of the volcanoe.
Volcanic gas:Gas from a volcano escapes and covers the sky and makes it hard to breathe.
Volcanic bombs: Volcano that spits out a high viscosity ball of lava.
Lahars:Mudslides of debris from a volcano that run down when a heavy rain falls.
Pyroclastic flows:Volcano has a small eruption and hot ash, lava fragments, and gases are ejected harshly and move at great speeds downslope.
Tsunami:Earthquake can trigger huge waves of water from a nearby source of water and the waves crash into land and can ruin anythingin their path.
Seismometers and seismographs are used to predict volcanic eruptions because they have good measurements of the ground near a volcano and can detect deformation well. Seismographs:Used to measure earthquakes by having a part that moves while the earthquake is happening and a part that does not.
Seismometers are used to help pinpoint where earthquakes happen and the magma flow and movement along fissures.
Very small earthquakes near the volcano, swelling of the volcano, and increased gas and heat are all ways to tell if a volcano is going to erupt.
We can predict using seismographs and seismometers, and we can tell where but not when.