Super moons and earthquakes

There are so many potentially rare events,
one of them is sure to happen.
David Brooks
PBS Nightly News

As I'm sitting at my desk now, I see an enormous full moon setting behind the clouds to the west. If you're lucky and have clear skies tonight, look for this "perigee" moon as it rises in the east. It will be 14% larger and 30% brighter than the ordinary full moon. The moon is as close to the earth as it will get for the next 18 years-- this increases gravitational pull on tidal and (perhaps) tectonic forces. Some meteorologists believe a supermoon might cause earthquakes, although this idea is controversial. But how about this? The last extreme supermoon occurred a few days after the 9.0 Indonesian earthquake in 2005.

About the time Mozart was composing music, out here in the Northwest wilderness a 9.0 magnitude quake occurred along the Cascadia subduction zone. Geologists know the exact date and time, because this earthquake sent an"orphan tsunami" across to Japan, where they recorded damage and loss of life. There have been at least seven "megathrust" earthquakes here in the last 3500 years, which suggests return times of 300-600 years. Oh boy. Are we overdue?

We don't get rattled often by earthquakes, and so we become complacent. Subduction zones similar to the Cascadia have big earthquakes every 100-200 years, so the long interval here means stress buildup causes unusually large quakes. The other unhappy earthquake phenomenon in Seattle is "liquefaction." Our sandy soil will become the consistency of Jello, causing building destruction similar to Kobe, Japan in 1995. If that's not bad enough, the tsunamis produced by these megaquakes reach 100 feet on the coast. To put that in perspective, the wave that just hit Japan was about 75 feet high.

So, other than moving far, far away-- is there really a way to "prepare" for a natural disaster of that magnitude? So just pore me another glass of wine, and we'll enjoy looking at the moon tonight.