Magnitude 8.8 earthquake off Chile coast

The entire universe in blog form
Feb. 27 2010 9:59 AM

Magnitude 8.8 earthquake off Chile coast

Last night at 06:34 UTC, a huge earthquake struck on the coast of Chile, with a reported magnitude of a numbing 8.8 -- making it one of the largest earthquakes recorded on Earth since 1900.

A tsunami warning has been issued for the entire Pacific ocean. This is no joke; the tsunami gauges in the deep ocean have registered a wave spreading from the quake. I don't know how big the amplitude is, but there have been confirmed reports of waves a meter high in Chile. That may not sound like much, but water weighs a ton per cubic meter/yard, so a wave that high has a lot of destructive power.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

Advertisement

The tsunami should hit Hawaii around 11:05 local time, and it's not clear at all how big it will be. In 1960, a larger earthquake happened off Chile and a tsunami hit Hilo, Hawaii causing quite a bit of damage. If you live anywhere near a Pacific coast, please check the local news and the Pacific Tsunami Warning Center. Also, a live stream of news from Hawaii is on HawaiiTsunami.com. I've been listening and the coverage is pretty good.

If you live in Hawaii, now might be a good time to check out that higher ground you hear so much about. At the very least, stay away from the beaches! People are already starting to evacuate the coasts, so if you choose to get out, the earlier you get moving, the better. Traffic is bound to get snarled. Please please please don't panic. Stay calm, and keep focused.

It's unclear if this will be a big wave or not. But if you're in Hawaii you should consider moving to higher ground.

Here is a map by the NOAA of the modeled energy wave expected from the earthquake:

noaa_2010_quakeenergy

It's unclear to me just how big a wave this means in terms of real height (it's a model, not an actual measurement), but it should bring home that you should take this seriously.

I'll note that the magnitude scale doesn't translate perfectly to energy released, but roughly speaking an 8.8 quake releases the energy equivalent of 20 billion tons of TNT, or 400 time the largest nuclear weapon ever detonated (Tsar Bomba, a 50 megaton test done by the USSR in 1961). If the measurement hold up, this will be the fifth or sixth strongest earthquake recorded since 1900. The strongest ever recorded, in 1977 1960, was magnitude 9.5, also in Chile -- the one that caused the tsunami in Hilo.

Thanks to Sean Carroll for the link to the energy map. Note also, in this post I referred to the Richter scale, which is no longer used. I corrected that.