What caused the 7.8 Earthquake in Sumatra and what are the details?

[russ_watters]

Just in (6:35 EDT, it's now 6:49), few details yet.

Epicenter: 2.236°N, 97.046°E (Next to an island, just off the coast)
Depth: 46 km

CNN: http://news.blogs.cnn.com/2010/04/06/usgs-earthquake-strikes-northern-sumatra/?hpt=T2
USGS: http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2010utc5.php
NOAA PTWC: http://www.prh.noaa.gov/ptwc/

 

[berkeman]

From the first link:

A "destructive widespread tsunami" is not expected, the Pacific Tsunami Warning Center said, but a local tsunami could affect coastal areas near the quake's epicenter.

At least that's good news. I wonder how bad the damage is.

 

[lisab]

From one of Russ's links, it was 46 km (28.6 miles) deep and about ~50 miles from the island of Sumatra (although there were closer small islands).

According to http://earthquake.usgs.gov/earthquakes/shakemap/global/shake/2010utc5/" , it was in the "strong to very strong shaking" range, with potential damage expected to be light to moderate, according to the legend on the map.

 

[Moonbear]

Interestingly, when I was watching the news about the CA earthquake, a seismologist was being interviewed and commented that earthquakes of about 7 magnitude happen pretty much monthly around the Earth. The only difference recently is that they've been hitting populated areas. (The reporter was asking about the significance of the recent series of magnitude 7+ earthquakes in the past few months...Haiti, Chile, CA.)

 

[rootX]

Interestingly, when I was watching the news about the CA earthquake, a seismologist was being interviewed and commented that earthquakes of about 7 magnitude happen pretty much monthly around the Earth. The only difference recently is that they've been hitting populated areas. (The reporter was asking about the significance of the recent series of magnitude 7+ earthquakes in the past few months...Haiti, Chile, CA.)

I don't understand tectonic plate movements. Why they would starting hitting on populated areas so frequently for past few years/months?

 

[cronxeh]

I can see it now. The 2012 conspiracy theorists will claim it was that huge solar flare from http://www.spaceref.com/news/viewsr.html?pid=33826"

 

[Evo]

I don't understand tectonic plate movements. Why they would starting hitting on populated areas so frequently for past few years/months?

Because at their last convention they realized that hitting unpopulated areas wasn't getting any press?

Or maybe it's because humans are building more on fault lines?

 

[zomgwtf]

Because at their last convention they realized that hitting unpopulated areas wasn't getting any press?

Or maybe it's because humans are building more on fault lines?

Or maybe saying that it's only started recently hitting populated areas isn't necessarily true. It's just happened closer together recently, which could just entirely be left to chance.

 

[russ_watters]

The Hati one hit pretty close to a heavily populated area. The Chili one was a near-miss...the CA one wasn't in CA, it was in Mexico, 110 miles from the nearest decent sized city (San Diego), ! That's selection bias.

 

[Astronuc]

I don't understand tectonic plate movements. Why they would starting hitting on populated areas so frequently for past few years/months?

Because many major cities are built along the coasts, and around the Pacific Ocean, this means those cities are near the subduction zones of the various tectonic plates.

Here is a map of all earthquakes of 7.0 mag or greater since 1973. Notice the distribution around the northern Pacific and across Asia. The orange dots are closest to the surface.

More stats - http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php

 

[rootX]

Because many major cities are built along the coasts, and around the Pacific Ocean, this means those cities are near the subduction zones of the various tectonic plates.

Here is a map of all earthquakes of 7.0 mag or greater since 1973. Notice the distribution around the northern Pacific and across Asia. The orange dots are closest to the surface.

More stats - http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php

Thank you.

Interesting graphs (Number of deaths due to earthquakes on yearly basis):
http://earthquake.usgs.gov/earthquakes/eqarchives/year/graphs.php
There weren't many deadly earthquakes during 80s and 90s

 

[berkeman]

Here is a map of all earthquakes of 7.0 mag or greater since 1973. Notice the distribution around the northern Pacific and across Asia. The orange dots are closest to the surface.

More stats - http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php

Small nit, but whoever came up with that map as USGS should learn their rainbow a little better. Oh well.