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While concern over the possibility of a major earthquake the Bay Area is warranted, an expert from the United States Geological Survey said locals need not fret much about the prospect of a tsunami hitting Mountain View.
“I wouldn’t want your readers to lose a lot of sleep over that,” said Tom Brocher, director of the earthquake science center for the USGS. “The seismic hazards are what they need to worry about, rather than the tsunami.”
Brocher, who is based in Menlo Park said that the narrow opening of the bay, along with its shallow depth, means that it would be highly unlikely for tsunami waters to do much damage to inland areas in the Bay Area, even in cities like Mountain View, which abut the bay.
Coastal cities are the most at risk from a tsunami, Brocher said. He also said that the Bay Area faults, such as the Hayward and San Andreas, aren’t likely to cause a tsunami.
“In this part of California, the tsunami risk is mainly related to distant earthquakes,” he said.
Faults in the Bay Area are mostly “slip strike” faults, Brocher said — meaning that they grind on each other when they move parallel to one another.
Large tsunamis are created by “subduction zone” faults, he said, areas where one tectonic plate is being forced under another. When faults like this experience a major shift the earth can suddenly drop or rise rapidly. If that happens with an underwater fault, that water will be shoved with great force and may result in a tsunami.
To illustrate his point, Brocher said that the massive 1906 earthquake, that razed most of San Francisco, only generated a swell of about 4 inches.
However, he said, just because Mountain View residents shouldn’t “lose sleep” over the prospect of a tsunami, doesn’t mean that they need not worry about the damage caused by a strong temblor.
There are many faults running through the Bay Area, he said. “We’re so close that the shaking is going to be very strong.”
It is important for families, as well as individuals, to have a plan in case of a major natural disaster, according to Jaime Garrett, public information officer for the Mountain View Fire Department. There are several places locals can go to help devise such a plan, including online and by calling the fire department at 903-6365.
There is also AlertSCC.com, where residents can sign up for automated alerts on their land lines, cell phones and e-mail accounts. The Mountain View Fire Department also has Facebook and Twitter accounts, where emergency information would be posted.
In the event of an emergency, information would also be available on local radio and television — 87.9 FM, KFFH and channel 15 KMVP respectively.
i don’t think its that big of a deal
What are the chances (%) of this happening in MV?
“Coastal cities are the most at risk from a tsunami, Brocher said. He also said that the Bay Area faults, such as the Hayward and San Andreas, aren’t likely to cause a tsunami.”
For anyone that actually needed this pointed out to them…unbelievable.
Actually, Brocher is right with respect to Mountain View. Our greatest risks here are related to the larger local faults, e.g. Hayward fault which is over due for a 7 range quake is an extreme risk for a Kobe or Port Au Prince like quake that would make a direct hit on the east Bay, even with our great resistant building codes, even resilient structures can suffer moderate to heavy damage in a direct hit 7.0 scenario (which might create up to Mercali VIII or IX level ground shaking), ditto for areas immediately above and adjascent to San Andreas (and its 7.9-8.0 potential).
However, we shouldn’t lose sight of the fact that slightly to the north of the Bay Area is the Cascadia subduction zone extending from Mendocino to British Columbia which is capable of producing 9 level moment magnitude quakes (& hasn’t had a large event since 1700).
One thing to consider is the possibility of much larger tsunamis that could affect the CA coastal communities from a Cascadia event at perhaps 10X the heights and extent inland as was seen this weekend from the Sendai megathrust event (wwhere we had well under 1 meter tsunami here this weekend and yet saw several harbors trashed and ~$100M in damage). Areas well away from the Sendai epicenter in Japan saw large tsunamis, great loss of property and life from up to 4-6 meter tsunamis that struck the north and even west coasts of Honshu and many areas of Hokkaido.
Of course he is right. But do we really need to ask what the possibility of a tsunami hitting Mtn. View is?
“United States Geological Survey said locals need not fret much about the prospect of a tsunami hitting Mountain View.”
In other words, the chances for a tsunami hitting MV in not zero?
“Mountain View would likely not be hit by a tsunami”
What about Los Altos Hills? Is there safer?