Deciphering Nature's Seismograph: How Sediments Record Past Earthquakes and Inform Future Hazard Assessments

People have been recording seismic activity for centuries. To assemble a detailed earthquake history of an area and understand how faults may behave in the future, however, scientists need to go further back in time—from several hundred to many thousands of years ago.

Paleoseismology is the study of earthquakes that pre-date modern instrumentation. For example, the 1700 Cascadia earthquake occurred before seismometers existed to measure it; the timing and magnitude was inferred from historical evidence such as sunken coastlines, salt-killed forests and written records of an "orphan tsunami" that reached Japan. Paleoseismology incorporates such evidence to help scientists understand the likelihood and risks of future earthquakes.