Lecture 11: Earthquake Prediction

Question 1

What data are needed to predict EQ? (5)

Answer 1

1) Historical and pre-historical data (paleoseismology) for M>6
2) Active monitoring (dense arrays of seismographs = better constraints on depth, location, magnitude, and focal mechanism)
3) Monitor “seismic gaps” and areas susceptible to “stick-slip”
4) Analogues: new research by Geological Survey of Canada plans to use knowledge gained by Chilean EQ record (frequent EQs) to predict style of rupture along the Cascadia Margin (Southern BC and Washington State area)
5) Improved modeling of seismic wave energy through different rock types (material properties, Young’s modulus)

Question 2

Direct volcano hazards (12)

Answer 2

Lava
Pyroclastic flow
Nuee Ardentes
Pyroclastic surge 
Ash fall
Acid rain
Bombs
Lahar
Debris avalanche
Shock wave
Lateral blast
Gases

Question 3

Indirect volcano hazards (3)

Answer 3

Change in groundwater
Lack of vegetation
Lack of solid ground

Question 4

Splatter cones

Answer 4

Numerous locations, even on other volcano types, low viscosity, basalt

Question 5

Shield volcanoes

Answer 5

Mostly ocean islands above mantle plumes (Hawaii and Iceland), basalt

Question 6

Stratovolcanoes

Answer 6

Volcanic Arcs above subduction zones (e.g. Maipo (Chile) or Mt. St. Helen’s (Washington State) andesite

Question 7

Caldera or super volcanoes

Answer 7

Involve continental crust, high viscosity, very explosive (e.g. Yellowstone, Long Valley) rhyolite

Question 8

How do we predict volcanic eruptions? (4)

Answer 8

Much easier than EQs

1) Previous eruptions are good indications, edifices are already there, so we know previous chemistry (viscosity) from the rock types
2) Monitor water content (viscosity), gas composition and volume (depth and composition of magma)
3) Monitor changes in steam temperature and topography (bulges on side of volcano)
4) Monitor local small EQs to sense depth, size, and ascension of magma