Scientists Discover Earthquake Threat That Could Devastate Millions
Scientists used tree rings to pinpoint an earthquake that occurred in the Puget Lowlands in western Washington about 1,000 years ago.
The earthquake was either the result of all the shallow faults in the region rupturing together, or twin quakes that occurred back-to-back.
Shallow faults typically result in more violent shaking than earthquakes generated from other geological configurations.
The earthquake from roughly 1,000 years ago caused a 25-foot cliff to be thrusted into the air,triggered a local tsunami, and stripped mountainsides of whole forests.
Scientists used tree rings to match the growth patterns of dead trees with patterns from living trees to determine when the earthquake-killed trees died.
The trees died in the exact same year across both the Saddle Mountain and Seattle faults.This suggests that these faults can rupture synchronously or in very rapid succession.
If the Saddle Mountain and Seattle faults went together, it would be on par with the 1906 earthquake in San Francisco.
If the quakes happened back-to-back, the infrastructure and landforms already weakened by one quake would be weakened by a second quake.
This could cause water mains to thrust up, roads to be severed, landslides to be triggered, and local tsunamis to occur.
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