This report was first published in this blog on May 16th. I decided to bring it back because of a report in today's (July 18th) San Francisco Chronicle covering the tsunami that hit Pangandaran, Indonesia this past Monday. More than 300 poeple were killed in this latest tsunami. More than 216,000 people died in the 2004 tsunami.
In both cases the victims were given no warning.
Although regional early-warning centers notified Indonesia that this latest deadly tsunami was approaching, the country has no system in place to warn its residents.
What happened in Indonesia can just as easily happen in California.
This is a second warning call to us here on the West Coast of the United States. WE HAVE BEEN WARNED!
Here then, is the original posting from May 16th:
Scientists tell us that San Francisco is much more likely to suffer a major catastrophe not from an earthquake on the San Andreas fault as in 1906, but from a mega-tsunami generated by a major earthquake occurring along the Pacific Ocean floor at the Cascadia Subduction Zone.
University of Washington student scientists Ray Flynn and Kyle Fletcher, with input from Ruth Ludwin and Bill Steele, produced a clear and concise report on the danger of the Cascadia Subduction Zone. It is a very long sloping fault that stretches from mid-Vancouver Island to Northern California. It separates the Juan de Fuca and North America plates.
New ocean floor is being created offshore of Washington and Oregon on an a continual basis. As more material wells up along the ocean ridge, the ocean floor is pushed toward and beneath the continent. The Cascadia Subduction Zone is where the two plates meet.
This is where all hell will break loose.
Great Subduction Zone earthquakes are the largest earthquakes in the world, and can exceed magnitude 9.0. Earthquake size is proportional to fault area, and the Cascadia Subduction Zone is a very long sloping fault that stretches from mid-Vancouver Island to Northern California. It separates the Juan de Fuca and North America plates. Because of the very large fault area, the Cascadia Subduction Zone could produce a very large earthquake, magnitude 9.0 or greater, if rupture occurred over its whole area.
The Cascadia Subduction Zone is one of the most dangerous places on Earth.
The last known great earthquake in the northwest was in January, 1700, just over 300 years ago. Geological evidence indicates that great earthquakes may have occurred at least seven times in the last 3,500 years, suggesting a repeat time of 300 to 600 years.
The Indonesian earthquake and tsunami of December 26th, 2005, produced an ocean surge that in some areas was more than 90-feet high. Trillions of tons of water were instantly raised from the ocean floor, creating a tsunami and quake that began some 60 miles off the northwestern shore of Sumatra and ripped along the seabed at 2 miles per second, traveling for nearly eight minutes, leaving a "rupture zone" that stretched to the north about 750 miles.
A 9.0 earthquake along the Cascadia Subduction Zone of our coast would likely create a tsunami so powerful that the ocean surge slamming into San Francisco would be as high as the base of the Ferry Building Clock Tower. It would sweep houses and buildings from their foundations throughout the Richmond and Sunset Districts and would scour much of San Francisco right down to the sand and bedrock.
A devastating tsunami is due ... any day now.
The last known major earthquake along the Cascadia Subduction Zone was 306 years ago. Scientists estimate another major, devastating earthquake in the 9.0 range may be expected somewhere between every 300 to 600 years. It can happen any time. It is due.
Get ready now! Learn what to do to save your life ...
The best way to prepare is to enroll in one of the San Francisco Fire Department's Neighborhood Emergency Response Team (NERT) training programs. They are free and conducted by professional firefighters of the SFFD. You may learn more about the SFFD NERT program here.
Story tools and references:
ABAG (Association of Bay Area Governments) Tsunami Page
Cascadia Megathrust Earthquakes
USGS Pacific Northwest Tsunami Facts
Cascadia Subduction Zone Info, USGS
Cascadia Subduction Zone Strain Monitoring
72-Hours.Org - San Francisco Office of Emergency Services
San Francisco Fire Department NERT
3 comments:
If people are too damn stupid to read the warning signs at Ocean Beach and end up drowning in the rip currents, then what on earth makes anybody think they will be intelligent enough to recognize the dangers of a tsunami and prepare accordingly!
I want to answer the previous comment. True, there are signs posted at Ocean Beach that warn the public about the dangerous rip currents that run between the submerged sand bars. Each year thousands of tourists visit Ocean Beach. Many of them know nothing or very little about the power and danger of the Pacific Ocean. Many of them come from communities that are hundreds, or even thousands of miles from the ocean.
San Francisco is one of the top tourist destinations of the world. We are hosts to people from every continent on the planet. Because we lucky enough to live in this magnificent City we are, by default, hosts to the thousands of visitors we see in our City every day of the year.
Would we not be hateful and arrogant people if we dismissed the death of others as easily as you seem to do because others do not meet your intelligence expectations?
We do not warn people about earthquakes and tsunamis because they meet some artificial standards we create for them. Rather, we warn people about potential dangers because we are good stewards of the City in which we live and because we genuinely care for the people who are our fellow citizens and those who are our guests.
San Francisco is only 7 miles by 7 miles. It is a compact city and we have a lot of people living here. We manage to make room for thousands of guests coming to see our City and we are happy to share our City with them.
Your reasoning is completely out of line and not acceptable. In San Francisco we want everybody to be accepted and nobody rejected.
- Sam Spade's San Francisco
Fortunately, most people living above Marin to the Oregon border are only all too aware of how prone the coast is to tsunamis ...the relatively low influx of newcomers to that region helps. As for the people with more money than sense who have desecrated much of the California coastline: while I wouldn't wish the tragedy on them, some of them seem hellbent on daring Mother Nature to keep on doing what it has done for millions of years. I'm glad for some passionate geology & geography profs back in the day who instilled what in me what I'd hate to think of as an aberrant continued interest in the topic and the consequences for the Golden State. In SLO, where my folks are at present, you get an alarm that gives you just enough time to e-mail your family goodbye before a tsunami hits the Diablo Canyon nuclear power plant. After all of the hullaballoo over the last week over the probability of when "the big one" (duh!) will hit ...who needs scary movies when you've got this kind of reality hanging over your head?
Post a Comment