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DisastersNew fault lines discovered in western Washington

Published 11 January 2012

Geologists have discovered a series of fault lines that criss cross several mountain ranges in western Washington

Geologists have discovereda series of fault lines that criss cross several mountain ranges in western Washington.

The discovery is particularly notable as it suggests that the state’s fault lines could all be connected with an earthquake in one region shedding light on activity in another.

The fault lines were found in several mountains including the Yakima, Manastash, Umtanum, and Rattlesnake.

Every one of those mountains has a fault or two associated with them,” said Brian Sherrod, a geologist with the U.S. Geological Survey. “And almost all of them haven’t had much work done on them yet.”

So far, according to Sherrod, geologists have mapped a series of fault lines that stretch across the Cascades and connect to faults as far away as Vancouver Island. This suggests that seismic activity on one side of the Cascades could result in movement on the other.

Geologists have only recently discovered the faults and are still in the process of understanding what they are capable of doing. It is currently unknown if they are even active, and if so, when the last time they shook.

It’s something that’s going to take a long time to figure out,” said Sherrod, who noted he began his research using work done by geologists in the 1970s and ’80s. “I view this as something I’ll be working on the rest of my career.”

The latest discovery has proven helpful for emergency responders as they now know that earthquakes are a possibility and must be taken into account in disaster planning.

John Schelling, the earthquake management program manager for the state Emergency Management Division, said, “It continues the need for recognition that no matter where you are in Washington, earthquakes are a reality.”

Schelling was careful to note that the new information does not suggest that a disaster is imminent, but the information does offer emergency officials a better idea of where an earthquake might strike.

Emergency officials can now gauge the level of response that may be required for a natural disaster, but Schelling does not expect emergency agencies to make many changes to the plans they already have in place.

Jim Hall, the director of Yakima County’s Department of Emergency Management Services, said officials currently take an “all hazard” approach in addition to special plans for seasonal disasters like flooding and other predictable emergencies.

The new information “hasn’t changed our plans, we’re just more aware of the hazard,” Hall said. “An earthquake is unique, but we would respond to that in the same way as we would anything.”

Currently the state Emergency Management agency and the Pacific Northwest Seismic Network share information so when an earthquake hits, local agencies will know in minutes.

According to Hall, if an earthquake were to hit west of the Cascades, transportation and commerce in the Puget Sound region would likely be affected. More specifically, the Yakima area, which receives 75 to 80 percent of its food from the west side would face serious disruptions.

In addition, Hall said that despite the low probability of an earthquake hitting Yakima, he worries that many of the buildings could be affected as they are older and were not built to withstand seismic activity. 

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