Friday, March 11, 2011

Japanese earthquake

The big geology news this morning is the 8.9 magnitude earthquake off Honshu, Japan.  Since it struck during the day on Friday (Japan time), there are going to be a lot of impressive images and videos coming through over the next few days (who in Japan doesn't have a camera phone?).

The epicenter (38.322° N, 142.369° E) and depth (24.4 km or 15.2 miles) makes it clear that this earthquake was directly related to subduction of the Pacific tectonic plate beneath the Okhotsk subplate as shown at right (I placed a red dot in the approximate location of the earthquake's epicenter).

Earthquakes as subduction zones can be very large and destructive.  The aftershocks from this earthquake are impressive, as of 10 am EST (1500 UTC) on Friday, March 11, I count 15 aftershocks of greater than magnitude 6 (those are all large earthquakes in their own right) and literally dozens from magnitude 5 - 6 (and many, many more smaller magnitude shocks).

See the National Earthquake Information Center (NEIC) for a real-time list of earthquakes around the world over the past week.

The seismic data for this earthquake shows thrusting and displacement of the seafloor.  This movement of the seaflor can result in a long-wavelength wave which can travel across the entire Pacific Basin - a tsunami when it reaches shorelines.  While coastal Japan experienced a significant tsunami, still waiting to hear about Hawaii and western North America.


  1. It is interesting stuff. Makes me wonder how a whirlpool can form from such a thing.,life,video,video-captures-boat-in-japan-tsunami-whirlpool

    I mean that is not the result of tectonic stress is it? It is either the collapse of a huge underwater space which managed to avoid filling with water run off, or perhaps it is a deep rift which is gushing and filling with water?

  2. The damage and destruction from the earthquake and tsunami in Japan looks massive! I hope the United States and other countries make substantial contributions to the relief efforts there.

  3. Seismic activity is the result of a solar flare on 13-15 February 2011.
    The largest number of thermographs (Portable Thermal Imaging Cameras), to search for people under the rubble by fixing heat of the human body, have the Japanese Self-Defense Forces. Мost of these cameras mounted on military equipment. Some quantity of IR cameras have their manufacturers in warehouses.
    Dubai can help to Japan more than any other. because in Dubai is concentrated 20% of construction equipment (mostly cranes) that may needed to clearing concrete rubble.
    Аdequate logistics for the delivery of this equipment has the U.S. Army and the operating companies of largest aircrafts An-124.

  4. There's no relationship between solar flares and seismic activity. If so, we'd expect to see a periodicity of 11 years in seismic activity like we do with sunspot activity and that doesn't exist.

  5. Regarding whirlpools, I didn't really know why one formed during the Japanese tsunami but it turns out they are common features of tsunamis and apparently form from wave refraction.