Fierce Planet

New Earthquake Fault Discovered

by Victoria M. Johnson

Another earthquake fault was discovered near Truckee, California, a town about 35 miles from Reno. Using laser imaging technology, the scientists with the U.S. Army Corps of Engineers discovered the fault while they were inspecting the Martis Creek Dam, a dam that already had major safety concerns due to considerable leakage and it’s proximity to three fault zones.

Strike-Slip Fault

Named Polaris, the new fault is an active 22-mile long strike-slip fault. The last time Polaris caused an earthquake was 15,000 years ago. Lewis Hunter, a senior geologist for the U.S. Army Corps of Engineers, says the fault could trigger a 6.5 to 6.9 magnitude earthquake. But because the fault connects to others, the magnitude could be even higher if they ruptured at the same time. Polaris holds the added potential of producing a flood if the Martis Creek Dam is damaged during quake activity.

Though the discovery of Polaris was unexpected, scientists claim there are hundreds of unknown faults around the world.

Do you live in a Danger Zone?

Everyone knows California is earthquake country.  But if you think living outside of California means you’re safe from experiencing an earthquake, think again. The U.S. Geological Survey provides earthquake hazard maps that reveal the true picture of danger zones in the United States. The bright red color indicates a high probability level of ground shaking.

Are you surprised to see that vivid red covering much of South Carolina? That’s due to offshore faults that could potentially shake up the Palmetto State. What about Tennessee, Missouri and Arkansas?  This New Madrid Seismic Zone is of major concern to geologists due to the possibility of several large earthquakes in a region of the country not prepared for such events.

While I expected Washington and Oregon to join California on the red zone map, Wyoming and Utah are a surprise to me.  The USGS updates their maps periodically to include new faults discovered, ground-motion model studies, and updated fault geometry.