Predicting the Eruption at Mount. Pinatubo: Methods (CS)

Question 1

History as a method

Answer 1

• Pinatubo last erupted in the 14th Century, with radiometric age dating showing it had erupted 4 to 5 times in the last 2000 years.
• Such infrequent eruptions are violent; the length of time between these suggests one is likely to occur.

Question 2

Seismic Monitoring as a method

Answer 2

• The USGS immediately established a radio-telemeter network of 7 seismometers around the volcano that measure the S-wave shadow and give a continuous 3-D overview.
• 40-150 earthquakes occur a day at 8km deep.
• Tiltmeters and geodetic networks installed to defeat new ground movement.

Question 3

Visual observation

Answer 3

-The US airforce flew daily over the volcano looking for signs of eruption. Surface change as well as the number and scale of steam emissions was recorded.

Question 4

Gas Emissions

Answer 4

• Helicopter flights take gas samples using correlation spectrometers.
• Sulfur Dioxide levels increase from 500 to 5,000 tonnes/day in 5 weeks.