Methods of Predicting Earthquakes

Question 1

Precursors

Answer 1

precursors are events or actions that signify an earthquake will happen

Question 2

Ground level changes

Answer 2

Uplift, subsidence or tilting for example.

After several Japanese earthquakes scientists could identify ground level changes had occurred, but only after the event is too late

Question 3

Foreshocks

Answer 3

• Minor seismic events that precede a major one.

- Foreshocks have been found to form a small ring around the epicentre, although this information is yet to be used

Question 4

Radon Gas Emissions

Answer 4

2009 study found 125 reports of radon gas changes before 86 earthquakes. However the changes:

• occurred up to a thousand kilometers away
• months later
• At all magnitudes.

Question 5

Dilation Theory

Answer 5

• Rocks along fault line become stressed
• Microscopic cracks open in surrounding rocks
• These cracks can change characteristics of the rock (suggested as water levels in wells, increasing radon release, electrical resistivity, temperature)
• If measured can indicate an impending quake

Hope is a pattern of activity can be identified

Question 6

Seismic Gap Theory

Answer 6

• “In areas where earthquakes are known to regularly occur but recent records show little activity, then stress must be building and a quake becomes more likely.”
• Loma Prieta 1989 earthquake on San Andres fault occurred after 20 years of dormant activity.