Topic 14 - Dynamic Earth Part 2: Volcanoes

What is a volcano?

a buildup of volcanic material into a hill or a mountain, the material has come out of a crack (a vent) in the ground

What comes out of a volcano?

lava, ash, gases (CO2, WV, and more), dust, steam - never smoke, and rocks of all sizes

what is magma?

melted rock material below the ground, under a lot of pressure, lots of dissolved gases

what is lava?

melted rock material above the ground, the pressure is decreased, the gases are released

what are the distinct types of lava in Hawaii?

AA and Pahoehoe

what is AA?

if lava cools quickly and moves fast it can tear into chunky pieces

what is pahoehoe?

If lava cools slowly and does not move too fast, it forms smooth ropy lava

what is ash?

pulverized volcanic glass

what is dust?

pulverized rock (blasted out of the volcano)

what are the three different ways volcanoes are classified?

active, dormant and extinct

what is an active volcano?

it has erupted within recorded history

what are some examples of active volcanoes?

Mount St. Helens, Mauna Loa, Mt. Etna, Mt. Pinatubo, Yellowstone NP

what is a dormant volcano?

the volcano is sleeping, has not erupted in “a while” but shows signs that it could erupt – ground rumbling, small quakes, there is heat in the area

what are some examples of dormant volcanoes?

Mt. Fujiyama, Mount Rainier, Mt. Kilimanjaro

what is an extinct volcano?

dead, no energy left to cause it to erupt. Cold, quiet

what are some examples of extinct volcanoes?

Some of the Hawaiian islands and others nearby

can the status of a volcano change?

yes, Vesuvius was thought to be dormant until the 1940’s

what are the different types of volcanoes (7)?

lava plateaus, shield, composite, cinder cone, dome, caldera and crater

what is a lava plateaus?

also called flood basalts, thin - runny lava not explosive

what is a shield volcano?

thin - runny lava, builds up into a shield shape, not explosive (called effusive)

what is a composite volcano?

well-known volcano shape, alternating layers of thick lava and volcanic ash – the escaping gas causes the strong eruptions

what is a cinder cone volcano?

smallest types of built-up volcano, cinders blast out of vent and accumulate close by, explosive eruptions

what is a dome?

form beneath the surface, magma chamber below ground, never erupted through the vent

what is a caldera?

large circular depression at a volcano's summit, forms when the magma chamber empties, summit collapses inward

what is a crater?

circular, smaller than a caldera, typically forms from the eruption or explosion of a volcano, not collapse

what determines the eruptive activity of a volcano?

temperature and the amount of silica

Cooler lava is …?

thicker - flows less

Hotter lava is …?

thinner - flows easily

The more silica, …?

the thicker the melted material

The less silica, ….?

the thinner the melted material

what comes out of a volcano that can affect people far away from the actual eruption?

gases - held inside the magma by pressure, pressure is released and the gases escape

what are the gases that are released from a volcano?

CO2 (carbon dioxide), CO (carbon monoxide), WV, SO2 (sulfur dioxide), NO2 (nitrogen dioxide)

what are pyroclastic materials?

hot broken rocks released from a volcano during an eruption

What is a lahar?

mixture of ash and meltwater – turns into a “mudslide”, thick dangerous deep river

what is a nuee ardent?

glowing or flaming clouds of incandescent (super hot) gas and dust

what effect can dust and ash have in the upper atmosphere?

can affect sunset colors, climate via sunlight insolation and temperatures