Thursday/ earthquake alerts

My phone got the test alert this morning. I expected it, but the sound still startled me.

On Sunday, it will be 20 years since the magnitude 6.8 Nisqually earthquake that occurred here in the Puget Sound basin, on Feb. 28, 2001.

We’re soon getting a smartphone ‘shake alert’ system that will produce as much as a 30-sec. heads-up, that earthquake tremors are on the way (see diagram below). Thirty seconds or less — so this is not the time to panic and freeze.  

My plan is to duck under my dining room table — or to run into the smallest room (the guest bathroom). The upstairs bathroom would be the plan for the second floor.

And if you’re driving?
US Geological Survey (USGS) recommends :
– Move your car as far out of traffic as possible.
– Do not stop on/ under a bridge or overpass or under trees, light posts, power lines, or signs.
– Stay inside your car until the shaking stops.
– When you resume driving, watch for breaks in the pavement, fallen rocks, and bumps in the road at bridge approaches.

Earthquake early warning systems like ShakeAlert® work because an alert can be transmitted almost instantaneously, whereas the shaking waves from the earthquake travel through the shallow layers of Earth at speeds of one to a few km/ sec (0.5 to 3 mi/ sec).  When an earthquake occurs, both compressional (P) waves and transverse (S) waves radiate outward from the epicenter. The P wave, which travels fastest, trips sensors placed in the landscape, transmitting data to a ShakeAlert® processing center where the location, size, and estimated shaking of the earthquake are determined. If the earthquake fits the right profile a ShakeAlert® message is issued by the USGS. The message is picked up by ShakeAlert® partners (cell phone service providers) which could be used to produce an alert to notify people to take a protective action such as Drop, Cover, and Hold On and/or trigger an automated action.
[Image created by Erin Burkett (USGS) and Jeff Goertzen (Orange County Register) and updated by Robert de Groot (USGS)].

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