Cinder Cone Volcanoes
- Conical shape, steep angled size, 1000 feet high.
- Commonly found on the flanks of other volcanoes
- Neraly 100 cinder cones on the flanks of Mauna Kea, Hawaii
- Initially form around a volcanic vent, made up of alternating layers of ash and cinders (blobs of lava from the volcano rom an eruption)
- During an eruption cinders are erupted and settle around the opening of the vent, then the ash will settle, creating the layers.
- Direction of the wind can cause an irregular shaped base
- Active for 9 years between 1943-1952
- Reached a height of 1200 feet
- Destroyed the nearby twon of San Juan and killed 3 people.
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- Broad, low in height, baal diameter ranges from a few km to over 100 km. The height is usually 1/20th of the width.
- Very runny lava, not very viscous, basaltic lava
- Usually travels quite far before solidifying
- Often found at divergent plate boundaries
- Nearby residents have been breathing in high levels of sulphur dioxide
- In 1990, an eruption created a lava field that engulfed the town of Kalapana
- There is acid rain from the released sulphur dioxide, damaging crops and buildings.
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Composite or Stratovolcano
- Tall cone shaped volcano
- Made up of lava, ash, pumice and tephra (rock fragments and particles)
- Much more explosive than Shield eruptions but less extreme than Calderas
- Magma is andesitic, meaning it contains alot of silica, making it very viscous.
- This plugs up the crater, making eruptions more explosive.
Mount St.Helens, USA
- May 18th 1980
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- Formed when the volcano collapses in on itself
- This occurs when the volcano erupts, expelling alot of magma, leaving the land above with no support below, leaving it to collapse inwards.
- Can be up to 100km wide
- Formed after a plinian eruption
- Massive eruption 1883
- Heard 300miles away
- Change dthe global temperature, down by 1.2 degrees C for 5 years
- Destroyed almost the whole island it was on
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Acid / Dome Volcanoes
- Form when andesitic lava solidifies quickly creating a steep sided convex cone
- Formed by repeated violent eruptions of slow moving lava
- High silica content in lava making eruptions violent
Mount Pelee, Martinique
- Erupted massively in 1902
- Killed 30,000
- Most killed by pyroclastic flow
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- Occur at divergent plate boundaries
- Linear vents, usually a few metres wide
- Basaltic magma rises through the cracks, not very viscous
- Eruptions are gentle and persistent
- The eruption is ongoing from 29th August 2014
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