Many of us dutifully participate in the Great American ShakeOut every October, during which time we practice the behaviors that will help us cope when (not if) a major earthquake hits: dropping to the floor, covering our heads with one arm and hand and holding on to whatever shelter we can find. It's a good thing to practice, and the ShakeOut offers an excellent opportunity to do that. It's also a good time to take stock of your emergency plan and update it as necessary.
Of course, earthquakes aren't limited to October, and sometimes nature itself is generous enough to provide its own reminder. Take, for example, last Wednesday's quake near Molalla.
The magnitude 4.0 quake, located about 30 miles south of Portland, didn't cause any major damage, but we're told it was felt as far as away as Scio.
Wednesday's earthquake hit in the same area as a more destructive magnitude 5.6 quake in 1993. The so-called Scotts Mills earthquake caused about $28 million in 1993 dollars, according to a recent story in The Oregonian. It extensively damaged both Molalla High School and the Oregon Capitol building (part of the reason why state Senate President Peter Courtney has been so intent on finding money for seismic work there). A bridge near Dayton was damaged and had to be closed.
But no one was killed in the 1993 earthquake, and only a few people were injured. Similarly, no injuries were reported as a result of last week's earthquake.
The next reminder of the Earth's pent-up power may not be as gentle. Much of the West Coast lies within range of the Cascadia subduction zone, a fault that lies offshore from Vancouver Island down to Northern California. Scientists say when (again, not if) the entire fault slips, the result could be a magnitude 9.0 earthquake that could cause massive damage and thousands of deaths. It could be weeks, if not longer, before officials are able to reach every affected area and power and other basic services are restored.
The last time a quake of that magnitude occurred along the subduction zone, it was 1700. Scientists say the chances of a quake hitting the central Oregon region of the subduction zone in the next 50 years are between 15 and 20 percent.
Let us be clear: That is not cause to panic. But it is cause to prepare, to be sure you have a functional plan in place for dealing with an earthquake (or, for that matter, any natural disaster). Government websites offer plenty of useful information about how to prepare, and the online version of this editorial offers links to sites that we've found useful.
Last week's earthquake also offered another useful test of the state's growing ShakeAlert system, a series of sensors throughout the state that are designed to give a few seconds of warning before the most dangerous waves of energy unleashed by a quake reach an area. The Oregonian story offered a useful primer: Quakes produce two types of energy radiating out from the epicenter: primary waves, or p-waves, and secondary waves, s-waves. The primary waves travel faster and usually don't cause much destruction; it's the s-waves, a few seconds behind, that cause the damage. The system under development senses the p-waves and sends a warning. Depending on the situation, the system could provide vital seconds of warning.
While that doesn't sound like much time, it could offer opportunity to reach cover. And it could provide time to stop a train or trigger automatic gas shutoff valves, steps that could limit the damage a quake could cause. Similar systems work well in other countries. The system here shows promise, but it needs $38 million to be completed. Even for a presidential administration that has shown consistent hostility to science, this seems like a no-brainer investment. (mm)