The Tortoise and the Hare: Slow vs. Fast Earthquakes

In the past decade, earthquake scientists have discovered a family of unusually slow earthquakes.  These slow earthquakes occur in diverse geologic environments.  Like ordinary earthquakes, they occur as slip on the same faults that host ordinary earthquakes, but they take a long time to unfold, such that they can be described as "slow."

Their discovery was enabled by deployment of highly sensitive earthquake monitoring networks.  Slow earthquakes are slow in a systematic way that leads us to define them as a new earthquake category in much the same way that astronomers categorized main-sequence and off-main-sequence stars nearly a century ago.

Unlike ordinary earthquakes, which grow explosively in size with increasing duration, slow earthquakes, whether large or small, grow at a constant rate.  They occur on the deep extension of large faults - a location that is "strategic" because it adjoins the part of the faults that generate the more familiar, and dangerous, "ordinary" earthquakes.  Slow earthquakes have the potential to trigger large earthquakes.  For this reason alone they merit intense study.

Dr. Gregory Beroza, Wayne Loel Professor, Deputy Director of the Southern California Earthquake Center and chair of the Department of Geophysics at Stanford University in California, will present “The Tortoise and the Hare: Slow vs. Fast Earthquakes,” on Monday, September 17, 2012 at 7 p.m. in the Pioneer Park Theatre. The lecture is open to community members of all ages for free.

Beroza’s lecture is sponsored by the Incorporated Research Institutions for Seismology and Seismological Society of America’s Distinguished Lectures Series. For a decade, the IRIS/SSA lecture series has enabled world-renowned scientists to travel and speak to public audiences about cutting-edge seismological research. This will be the first IRIS/SSA Distinguished Lecture to be hosted in Alaska.