Volcano

• The magma chamber is the source of volcanic eruptions.
• Magma rises from the mantle to the surface through fractures, faults or fissure vents.
• Volcanic activity can be explosive (violent) or effusive (quiet).
• Magma rises to the surface through cracks or fissures, forming lava flows on the Earth's surface.
• Volcanic ash can be carried by wind over long distances.
• Lahars are mudflows that occur when water mixes with volcanic material.
• Volcanoes are classified based on their shape, size, location, type of material ejected during an eruption, and frequency of activity.
• Explosive eruption occurs when gas bubbles expand rapidly due to high pressure, causing an explosion that ejects ash and rock fragments into the air.
• Shield volcanoes have gentle slopes and are built up by repeated lava flows over long periods of time.
• Effusive eruption occurs when lava flows slowly out of the vent without much force.
• Cinder cone volcanoes are small conical hills formed when hot ash and rock fragments accumulate around a central vent.
• Lava flow rate depends on viscosity, which varies with composition.
• Lava flows are slow-moving rivers of molten rock that flow downhill.
• Pyroclastic flows are fast-moving clouds of hot ash, gas, and rock fragments that travel at high speeds along the ground.
• Ash plumes are columns of fine particles of solid material ejected into the air during an eruption.
• Pyroclastic flow is a fast-moving cloud of hot gas and rock fragments that moves down the side of a volcano during an eruption.
• Shield volcanoes have gentle slopes and are built up slowly over time.
• Ash clouds can cause air travel disruption.
• Cinder cone volcanoes form quickly and consist mostly of cinders and small rocks.
• Effusive eruptions involve slow-moving lava flows from vents at the summit of the volcano.
• Composite/stratovolcanoes have steep sides and are formed by repeated layers of hardened lava and ash.
• Tephra refers to all types of solid particles ejected into the atmosphere during volcanic eruptions.
• Composite volcanoes (stratovolcanoes) have steep sides and alternate layers of hardened lava and ash.
• Stratovolcanoes have steep sides and are made up of alternating layers of hardened lava and ash.
• Cinder cone volcanoes are small conical hills formed from cinders (ash) and scoria.
• Shield volcanoes have gentle slopes and are formed by repeated eruptions of fluid basaltic lava.
• Cinder cone volcanoes are small conical hills formed from cinders (ash) and scoria.
• Cinder cones form from explosions at composite volcanoes and consist of loose piles of cinders and rocks.
• Hawaiian volcanoes are shield volcanoes found only in Hawaii and other hotspots.
• Viscosity is related to the amount of silica (SiO2) present in magma.
• Composite or stratovolcanoes are steep-sided mountains made up of alternating layers of hardened lava and ash.
• Phreatomagmatic eruptions involve steam explosions caused by groundwater coming into contact with magma.
• Hotspot is a place where molten rock rises from deep within Earth's mantle.
• Basaltic lavas are less viscous than rhyolitic lavas because they contain more iron and magnesium and less silicon dioxide.
• Volcanic bombs are large pieces of solidified magma ejected from a volcano during an explosive eruption.
• Pyroclastic flows are fast-moving clouds of superheated gases and solid particles that can travel at speeds exceeding 700 km/h (435 mph).
• Volcanic bombs are large pieces of rock or other materials thrown from a volcano by explosive forces.
• Ashfall refers to fine particles of tephra deposited on the surface as a result of a volcanic eruption.
• Tephra is any material ejected from a volcano during an eruption, including ash, pumice, cinders, and lapilli.