Predicting and Forecasting Earthquakes

Predicting Earthquakes

• humans (including scientists) can’t predict earthquakes
  • no such thing as “earthquake symptoms”
  • risk assessment is better

Prediction vs Forecasting

• prediction: when will the next megathrust earthquake of >M8 happen in the pacific northwest?

• forecast: what is the likelihood that a megathrust earthquake of >M8 will happen in the pacific northwest in the next 100 years?

Forecasting Earthquakes

• use evidence of past earthquakes
  • historical earthquakes
  • geologic record
• to find frequency of past earthquakes (return period)
• useful for long term, imprecise prediction (or forecasting)
• leads up to preparedness and good construction practices

Earthquake Warning Systems - Japan

• alarm goes out when P - Waves are detected by seismometers near the epicenter
  • linked to cellular networks, TV, and radio
• warning time = difference between P and S - wave arrival time
  • seconds to minutes