Disaster Day

San Francisco's First Skyscraper, April 1906

April 18 is probably the most important day in San Francisco's history.  Its the anniversary of the Magnitude 7.9 1906 Great Earthquake and fire which destroyed the city.  It was the costliest natural disaster in Earth's history at the time.  Commemorations are held each year with dignitaries and an ever shrinking list of the quake's survivors at "Lotta's Fountain", a landmark on Market St. at 5:12 AM.   I attended the ceremony in 2006, along with a crowd of tens of thousands of other early risers.  As the exact hour and minute of the 100th anniversary approached, a hush came over the crowd, and people whispered nervously "could there be another quake on the anniversary?  What are the odds?"

This year on Apr. 18 I was scheduled to give a presentation on the Tohoku Earthquake and Nuclear Crisis, the subject of this blog, to San Francisco State, as part of College of Science's presentation on the quake, tsunami and nuclear crisis I mention in my last post.   However, one hour before the talks were to begin the campus suffered a massive power outage which also took out electricity in the surrounding areas.   After walking from my building to the venue (in the vain hope that a different building would have electricity), I was locked inside the room as officials secured building.   As time went on it became clear that we wouldn't get power back, but that a large number of people were interested.  Dean Sheldon Axler asked the participants if they could give their presentations without visuals, and we all agreed.  "The show must go on."  The room wasn't entirely dark since large windows permitted sunlight in.   I was personally quite disappointed because the event had been my idea in the first place and I'd put considerable work into my presentation.  Nonetheless the presentations all went well, and I was happy with the turn out.

Immediately afterward I had to teach my Astronomy 115 class in a darkened 160 seat lecture hall.  attendance was low, around only 100 students, and there was no way for students to see the white board or to see their own notes.   So I ditched my planned lecture on colliding galaxies and simply opened up the floor for students questions on thing the didn't understand well or though should be covered in this class.  This proceeded for some 45 minutes when suddenly we all the room shake in an abrupt jolt.  As people looked around  and began to say "earthquake?"...a second more powerful jolt struck.  At the front  of the class I shouted "that was an earthquake!  Everybody leave the building!"   I was quite jittery from the days events, and began to speculate.  The jolt was so sudden, and lacked the usual swaying feeling of a quake, that I wondered if it wasn't actually an explosion.   I remembered the huge deadly explosions in PGE's gass lines a while back, and PGE was working nearby to fix the electricity proglem.  Could the days two disasters be connected?

I decided to leave the campus and see how my wife and child were at home.  Before collecting my bike, I swung by the Geosciences office for some quick information.  There I met Prof. Ray Pesteron, with whom I shared the stage earlier and Miriam Knof, Geosciences office manager, whose delightful smile and assistance can always be found in that office.   Ray informed me that it was indeed a quake and that what I had felt was first the P-waves hitting then the S-waves.  Since the were so close in time, the quake must be nearby.  We then made guesses as to the quake's magnitude and distance.  Ray said 3.5 within 10 miles and I said 4.0 within 20 miles.  We later learned that it was 3.8 and only a few miles away.   In fact the San Andreas fault, the same fault that caused the 1906 quake had again moved exactly 105 years to the day later!   Ray said the fault "was just trying to remind is: I'm here.  Don't forget about me, with all this activity in Japan!"

In case you missed my presentation...or incase you were there! the slides can be found at:

http://physics.sfsu.edu/~chris/