Posted by: drgeophysics | March 15, 2011

Tragedy in Japan.

I have been following the earthquake and tsunami damage in Japan very closely.  I learned of this earthquake very early on Friday morning, around 6AM.  I had been watching earthquake activity offshore Japan for the proceeding days and was worried (as I always am with respect to seismic hazards in Japan) about a repeat of the 1923 Kanto earthquake in which more than 100,000 people died.

Here are some images:  The Wiki that I took the information from is found here:

This is what keeps geophyscists from sleeping when thinking of Japan.

This entire slide is taken from Wiki:

A few days before the earthquake I had noticed large off-shore earthquakes showing up on quake.usgs.gov.

Foreshock I noticed and worried about.

This is the onestop for earthquake related information.  It is linked to this site on the right-hand side.   The focal mechanism showed the worst possible motion with respect to Tsunami generation.  Tsunami means “harbor wave” in Japanese and was given to waves that seemed to be caused by Harbors.  Fisherman returning from far at sea would return from their work to find entire towns and villages mysteriously destroyed by these waves, which they had not seen.  The violence of Tsunami motion comes from the density of water and the debris picked up by a rapid surge of water.  Although we think of walking around with glasses of water or carrying a 20 liter gasoline can, a cubic meter at 4 degrees Celsius weights 1,000 kilograms.  This is a metric ton in a cubic meter of material.   With this material then picking up cars, buildings, steel, soil and other material and it just knocks down everything in it’s path.  There is no escape for people caught up in this.

It was sickening to think of this and the density of people living in eastern Honshu Island.  I checked Shemya, Alaska and found that the Tsunami, this is one of the first places to which these waves arrived, was only 2 meters.  It was a relief that only limited Tsunami damage was suffered in other regions of the Pacific.  The importance of the Tsunami Warning Center was confirmed.

After shocks every hour.

This is a nightmare for the people living in Honshu.

The bravery of the rescue workers is of the first caliber and hard to imagine or describe.  There were aftershocks nearly every five minutes for the day following the main shock.  While each of these represents no danger to people in undamaged buildings, these rescue workers were crawling into tsunami destroyed buildings and each represented real danger.

Some updated numbers: as a 9.0 magnitude earthquake this event released 474 megatons TNT equivalent of energy, and was 1000 times (with respect to energy release) larger than the 7.0 Haiti earthquake.

The Harvard Seismology preliminary rupture model of the March 22, 2011 earthquake and sequence of events can be found here.

The USGS Earthquake Summary Poster can be found here.

The generation of reactors now in serious problems has been a global problem.  This NYTimes article shows that since 1972(!) the basic safety of the design was in serious question.

The tsunami hazards for these facilities and similar facilities needs to be rethought.  Let’s stay focused.  Plate tectonics and spatial analysis of geohazards provides a strong background to understand and mitigate these sorts of hazards.  There are important lessons to be learned from this sad and tragic event.  I hope that our children are safer because of our taking these lessons to heart and making the world safer.  Tsunami, earthquakes, volcanic eruptions, floods and other geohazards are part of our restless earth.  We can mitigate them all with careful and science based spatial and engineering analysis.   I am worried that this earthquake event has changed the stress tensors in the central Honshu region around the Tokyo region.

Video from Oirase Town, Aomori Prefecture.

Video from RT.  Seawall overwhelmed.

Video from Crescent City, California.

Video from above beach Crescent City, California.

Time Lapse of tsunami arrival at small marina, Crescent City, California.

Related to risk assessment, bowtie model is described here.

FEPS, Features, Events and Processes, is described here.

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