On shaky ground
November 24, 2008 · Updated 7:13 PM
Today a study team from the University of Washington will present a newly completed map detailing the Island’s precarious position atop a couple of active geologic faults. A presentation for Islanders to hear and see more about the map will be held at noon today at Mercer Island City Hall.
A map of the Island and its geological characteristics had not been done for decades. The map is one in a series of new geologic maps begun in the Puget Sound region in 1998. A major earthquake in the region in 2001 brought even more attention and more data to the mapping project.The map and its components will be key in planning for new development in the coming years.
The new map offers a detailed and sobering look at the Island’s position within the boundaries of the Seattle Fault.
According to the data, the Island is criss-crossed by three smaller fault lines. The map also defines the soils, the geologic formations and patterns of land development that increase the risk of building and living in certain areas.
It is not breaking news that the Island is in the midst of an active earthquake zone; our situation is well-known. However, the Island and the region are now home to thousands. What is of immediate concern is the high probability of the Island’s isolation if a large earthquake does occur, damaging I-90 and key infrastructure. A major earthquake could damage or break our water supply line that runs under Lake Washington from Seattle.
The city has already begun addressing the need for an emergency water supply and has extensive emergency preparedness plans in place. Let’s support those plans, familiarize ourselves with them, and make a few of our own.