Visualising the New Zealand earthquake

New Zealand is very active for eathquakes and vulcanism, unlike its bigger brother Australia, which is perhaps the most tectonically stable piece of crust floating around anywhere on this ball of magma. Thats because NZ sits atop the place where the Pacific ocean floor dives down under the aforementioned Australian plate. On September 4th there was a big slip around Christchurch, resulting in an eathquake measured at 7.4 in magnitude, which damaged hundreds of buildings and was felt all over New Zealand. Chris McDowall is a kiwi informatician who assembled 6 months of NZ earthquake activity into a cool data visualisation that shows just how common it is for the ground to move down there. Each earthquake appears as a purple blob, of intensity matched to the magnitude of the temblor, leaving a little red mark behind to show the accumulation over time. I was struck by how much of the activity is concentrated in two parallel lines running southwest-northeast on the north island. When the Christchurch quake hits the middle of the south island it just seems so big and out of place. Anyway, its a great bit of data visualisation and I thought you might like it too. Via my colleague Malcolm Bowman at Stony Brook U.

Visualising six months of New Zealand earthquake data (Apr 1 - Sep 7, 2010) from Chris McDowall on Vimeo.

What do expectant parents and the Chilean earthquake have in common?

The recent Chilean earthquake was a disaster on a mind-boggling scale; one that had its genesis beneath the sea.  The temblor, and all those in Chile before it, including the biggest ever recorded anywhere, resulted from the Nazca plate sliding down under the South American plate, under the sea to the South West of Santiago.  Well, it doesn't exactly slide, I always imagined it would sound like a creaking door if you could speed up the process a few zillion times.  The upward pressure this collision puts on the South American plate is immense and produces the longest mountain range in the world, the Andes.

Anyway, this most recent slip, which shifted about 10 meters and registered 8.8 on the Richter scale, caused a small tsunami.  Now some researchers from Scripps and UCSD want to know whether it was because of the sea floor movement itself, or because the quake triggered undersea landslides ("slumping") that produced the wave.  They are going to do some nifty multi-beam sonar work to map the seafloor changes in unprecedented details.  Sonar technology has become a really cool tool these days; the same sorts of benefits that new parents reap when they ultrasound their new bundle of joy also give scientists a fantastic new view on the sea floor.  Just check out this example of a shipwreck revealed by NOAA's nautical survey side-scan sonar.