GEL 1 Lecture Notes - Lecture 14: Nea Kameni, Mount St. Helens, Resurgent Dome
Review:
why do we have explosive eruptions?
● combination of high silica and high volatile contents
How do we monitor volcanoes?
● satellites to measure ground deformation
● volcano "breathing" mountains lift up ~20 centimeters at a time
○ magma moving around
○ baseline behavior
caldera
● erupting magma leaves a hole in the ground (empties the magma chamber), surface
collapses
● crater lake
● resurgent dome (the island in the middle)
● still active
some well known eruptions during recorded during human history
● Mount St Helens in 1980
○ mountain height decreased by 1330 ft
○ also has a resurgent dome
○ vertical spewing of ash
○ lateral blast bc weak spot on the side
○ stratovolcano
● Santorini, Greece (Bronze age, 1645 BC)
○ turned one island into 3
○ Kameni Islands: the resurgent portion
○ in the ocean so didnt make a lake
○ reduced crop years
○ buried by ash
● Pompeii, 79 AD
○ Roman city destroyed by Mount Vesuvius in 79 AD
○ just far enough away that it got preserved, was rediscovered in 1748
○ major trading hub
○ had to have at least one major earthquake that broke a plug in the volcano
○ pressure build-up, kicked off by another earthquake event
○ volcanic ash w/ some water is very similar to concrete, and more dense
■ collapses the buildings
○ cast of victims at pompeii killed by pyroclastic flow (solidifying ash)
Document Summary
Combination of high silica and high volatile contents. Volcano breathing mountains lift up ~20 centimeters at a time. Erupting magma leaves a hole in the ground (empties the magma chamber), surface collapses. Resurgent dome (the island in the middle) Still active some well known eruptions during recorded during human history. Lateral blast bc weak spot on the side. In the ocean so didnt make a lake. Roman city destroyed by mount vesuvius in 79 ad. Just far enough away that it got preserved, was rediscovered in 1748. Had to have at least one major earthquake that broke a plug in the volcano. Pressure build-up, kicked off by another earthquake event. Volcanic ash w/ some water is very similar to concrete , and more dense. Cast of victims at pompeii killed by pyroclastic flow (solidifying ash) Most believed to have been killed by the surge deposits (burned), body.
