Big Wave Project and the Cascadia Subduction Zone


By on Sun, March 20, 2011


The letter below was delivered during public comment at the March 15, 2011 San Mateo County Board of Supervisors meeting.  The comment was made for agenda item 7, “Tsunami Awareness Week”.  Agenda item 8 was the Big Wave Project.  Agenda item 8 was postponed until the next board meeting on Tuesday, March 29, 2011 at 9:00am.  If you have concerns about this project you should phone and/or email the Supervisors.

Tuesday, March 15, 2011

Re: Big Wave and the Cascadia Subduction Zone

Dear President Groom and Members of the Board,

We are witnessing a disaster unfold in Japan that was beyond our imagination last week. On Friday, March 11, 2011 a massive 8.9 earthquake triggered a tsunami that killed thousands and devastated coastal cities and villages, transforming them into debris piles.

We have seen the images on the internet and television of seawalls and breakwaters being overpowered by the tsunami in Japan, right now the Crescent City fishing fleet is wiped-out, Santa Cruz Harbor has a projected loss of 17 million dollars in property damage and just last year the seawall at Pillar Point was over-topped during the Mavericks surf contest, injuring spectators.

San Mateo County Planning Commissioners were not adequately informed by the Planning Department about the significant risks to human safety posed by the Cascadia Fault before they voted to approve a residential facility for developmentally and physically challenged people in a tsunami inundation zone. As Supervisors it is your responsibility to reverse this decision before people with Mental Retardation, Cerebral Palsy, Down Syndrome, and Autism are placed in the path of tsunami.  Today, society has a much deeper understanding of the level of risk posed by tsunamis and planning decisions must take this broader understanding into consideration. When a tsunami pushes a wave of boats, cars, and buildings against a structure significant damage and failure occur.

In April 1946 the tsunami that hit Hawaii had a fifteen-minute interval between wave fronts.  The natural resonant period of Hilo Bay is about thirty minutes.  That meant that every second wave was in phase with the motion of Hilo Bay, creating a seiche wave in the bay.  As a result, Hilo suffered worse damage than any other place in Hawaii, with the tsunami/seiche reaching a height of 26 feet along the Hilo Bayfront, killing 96 people in the city alone. Seiche waves may continue for several days after a tsunami.  The same tsunami hit Princeton and the wave height reached the top of Romeo Pier.

The Big Wave developers have stated that the probability of a tsunami affecting the Wellness Center is approximately once in 10,000 years, which is a risk they are prepared to take. They are wrong.  In fact, the Big Wave project Draft ERI itself references reliable reports of significant damage in Princeton on April 1946, May 1960, and March 1964.

As you may have seen in the news articles surrounding the tsunami in Japan, the Cascadia subduction zone off the west coast of the United States is capable of producing a massive quake and tsunami that would rival Japan.

Recent findings conclude that the Cascadia Subduction zone is more complex and volatile than previously believed. Geologists predict a 37 percent chance of a M8.2+ event in the next 50 years, and a 10 to 15 percent chance that the entire Cascadia Subduction will rupture with a M9+ event within the same time frame.  Link:

The southern end of the Cascadia Fault is approximately 370 miles NW (130 Degrees) of the Big Wave project location. At an average speed of 500 mph, there would be approximately 44 minutes of warning, assuming that the source and threat are immediately identified. Then there are all of the logistics and associated chaos of evacuating a large number of people, immediately—which as we just experienced on Highway 92, is not an orderly process, even when you have more than five hours of advance notice.

The Wellness Center residential component of the Big Wave project is a well-intentioned idea, in the wrong location. After witnessing so much loss of human life, suffering, and homelessness in Japan over the past five days, it would be criminal to approve the construction of new housing for special needs people within the tsunami inundation zone.  The risks posed by the inappropriate project site far outweigh the benefits for residents of the Wellness Center.  Developmentally disadvantaged people deserve better.

You can prevent loss of life by your actions today. Not only can you deny this project, you can initiate actions to prohibit future construction of housing, schools and care facilities in tsunami inundation areas.

Your meeting agenda includes Tsunami Awareness week.  You have a responsibility to locate residential facilities for people with disabilities away from the tsunami inundation zone.

Thank you,

Sabrina Brennan