Weather Service forecasts .78 meter tsunami for Coastside

Breaking news

Posted by
Fri, March 11, 2011


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National Weather Service
Map of tsunami energy forecast

A tsunami is expected to strike the Coastside between 7:30 and 8:00 am, driven by a magnitude 8.9 earthquake in Japan.

The National Weather Service forecasts that the amplitide of the tsunami is to be .78 meters at Half Moon Bay. By comparison, a tsunami of 2.2 meters amplitude was measured at Princeton in 1960.

San Mateo County is evacuating areas west of Highway 1 to higher ground. Evacuation areas are Farallone View Elementary School in Montara, Pescadero High School, and Terra Nova and Ocean High Schools in Pacifica.


Just got a phone call at 6am from Cabrillio Unified School District that school is closed today due to the tsunami warning.

Full map is here:

San Mateo County’s alert system is here: https://www.smcalert.info/latest.php

No big deal here in Moss Beach.  The estimate of ~3 ft seemed pretty accurate, along with the arrival time.  Fortunately, the tide was pretty low (+1 ft), so the regular tide + tsunami is about +4 ft or so, well below the +6 ft high tides that we often get.

I’m looking at the damage at Santa Cruz harbor, and hoping that everything’s OK at Pillar Pt. Harbor.  No news is good news, I guess, but I’m staying away from there for the time being.

I’ll post a link to the video of the tsunami once I get it uploaded.

just heard an official vehicle (well, sort of heard it - got the rest from a neighbor) that the warning has now been reduced to an advisory for Montara residents. I’m guessing it’s the same for the rest of the area. I’m well above the water so haven’t been concerned but being new to the coast I’m not quite understanding what the system here is in these situations. I have to admit what I’ve witnessed so far has been pretty haphazard and hasn’t exactly inspired confidence. Scant information available this AM and just now a loudspeaker announcement that if I hadn’t had the deck door open I wouldn’t have understood a thing. As it was I had to get half of it from a neighbor who was able to run up to the vehicle as it left to ask them what they’d just said.

In case you thought the breakwater would save us…

The Kamaishi, Japan, breakwater was in the Guinness World Records as the deepest on the planet. It was a product of decades of research on wave dynamics and dissipation. But the tsunami made short work of it.

Los Angeles Times LINK: http://www.latimes.com/news/nationworld/world/la-fgw-japan-quake-breakwater-20110314,0,4883014.story

Seawalls prove to be counter productive…

At least 40 percent of Japan’s 22,000-mile coastline is lined with concrete seawalls, breakwaters or other structures meant to protect the country against high waves, typhoons or even tsunamis.

The risks of dependence on seawalls were most evident in the crisis at the Daiichi and Daini nuclear power plants, both located along the coast close to the earthquake zone. The tsunami that followed the quake washed over walls that were supposed to protect the plants, disabling the diesel generators crucial to maintaining power for the reactors’ cooling systems during shutdown.

New York Times LINK: http://www.thepelicaneye.com/2011/03/seawalls-offered-little-protection-from.html