Geology AS case studies

Mount Pelée is an active volcano at the northern end of Martinique in the Caribbean. 

Worst volcanic disaster of the 20th century. The eruption killed about 30,000 people.

Pyroclastic flows completely destroyed St. Pierre, within minutes of the eruption.

The eruption left only three survivors in the direct path of the volcano.

Mount Pelée is on a subduction zone.

About 2 years before, signs of increased fumarole activity were present in a crater near the summit.

Located in the Pilipines.

Stratovolcano, on Island arc.

Many small earthquakes preceded the eruption, growing in magnitude and increasing in frequency.

Sulfur dioxide emissions increased substantially before eruption.

Citizens were evacuated 10 weeks before eruption, saving 5000 lives and ~$250 million in property.

Syncline dipped into valley.

Heavy rainfall caused land to slip.

Oct 9th 1963, 10:41pm south wall slipped into reservoir.

270 million cubic metres of rock.

wave 100m above dam.

Dam survived.

killed 20,000 people in Longorone.

slope was creeping at 2cm/week and increased to 20cm/day.

Caribbean Sea.

Warning signs: Small earthquakes, small eruptions of dust and gas.

Subduction zone (South american plate going under Caribbean plate).

Southern half of island successfully evacuated. (2/3 of population)

Main city (Plymouth) destroyed.

Eruption killed 19 people.

Team on roofs, shoveling ash off.

Sprayed lava flow to stop it and save harbor.

USGS says no apparent danger.

Next day eruption.

Town of Armero destroyed by lahar.

22000 dead.

Nazca plate being subducted beneath S. American Plate.