Earthquakes explained: faults, waves and Richter scale
Faults stick then slip, sending seismic waves; each Richter step means 32 times more energy.
Faults that stick then slip
Plates lock on faults for 100 years while stress builds 5 centimeters yearly. When friction breaks, blocks jump 10 meters in 10 seconds. The 1960 Chile quake slipped 20 meters over 1,000 kilometers.
Ruptures send fast pressure waves at 6 kilometers per second and slower shear waves at 3.5 kilometers per second. Buildings 10 stories tall sway most when 1 second waves arrive 100 kilometers from epicenter.
Scales and survival
The Richter scale is logarithmic: magnitude 9 releases 1,000 times more energy than magnitude 7. Chile 1960 reached 9.5 with 2,000 deaths, while Japan 2011 hit 9.1 and made 40 meter tsunami waves.
You cannot predict exact day but early warning gives 60 seconds after detection 100 kilometers away. Safety rule is Drop Cover Hold On under sturdy tables, then check gas leaks and 3 day supplies.
- Faults lock 100 years then slip
- Waves travel 3.5 to 6 km per second
- M9 is 1,000 times M7
- Chile 1960 was magnitude 9.5
- Japan 2011 was 9.1 plus tsunami