Presentations on tsunamis and preparedness were given by Eric Boldt of the National Weather Service as well as Sgt. Mike Carriles and deputy Bryan White of the county Sheriff’s Department Marina Station at the Marina Affairs Committee meeting April 20.
Boldt, the warning coordination meteorologist for the National Weather Service, presented information on what tsunamis are, their impact, and how they are tracked. Carriles and White, who serve with the sheriff’s Marine Operations Unit, discussed the importance of a safety plan in the event of a tsunami.
Tsunami is a Japanese word meaning “harbor wave,” said Boldt.
“It’s really important to know that it is a series of waves created by a sudden displacement of seawater. With an earthquake underwater, the plates are moving against each other. The stress causes the points to move together, and then pop back and spring the water up, displacing it.
“That’s when the tsunami gets generated. It’s similar to a kid throwing rocks into a pond and seeing the waves spread out,” he explained.
When a tsunami occurs, the National Weather Service detects and monitors the tsunami, and notifies people and governmental agencies in the affected areas. Boldt spoke of the recent response following the large earthquake and tsunami in Japan.
“Multiple waves bounce off islands and other waves and reflect and cause problems,” he noted.
“The last 13 months, we’ve had two very significant tsunamis on the West Coast and we’ve had damage, he said. “Ventura Harbor had $100,000 in damage after the last event and $250,000 in damage after the Chilean earthquake and tsunami. Morrow Bay had almost $500,000 in damage in the last event.
“There was movement of navigational buoys in the Marina harbor; Port of Los Angeles had eight feet of water left under its ships after the arrival of the Chilean tsunami – that’s bad news if they bottom out.
“When you hear ‘it’s coming at low tide and that’s good’, that’s not necessarily okay because you have damage and problems when the water gets drawn out so much that the water level is lowering,” said Boldt.
“In California, you could have a landslide, an earthquake just off the coast that could cause a tsunami. On March 11, the epicenter was just off the coast in Japan around 2:30 in the afternoon, local time, and lasted up to six minutes. It was a long duration and an incredibly devastating earthquake. That is a big signal for a tsunami, a long duration earthquake.
“Looking back in time, from 1900 to now, only a handful of earthquakes get up into the nines or higher, such as in 1964 in Sumatra,” Boldt said of the events’ magnitude on the Richter Scale.
“Japan started out below a nine and then they raised it to a 9.0. There are a lot in the eights, one per year, roughly that get to 8.0. After the earthquake in Japan, the tsunami hit land in as little as 10 minutes. It was very measurable after 20 minutes. We’ll focus on long distance tsunamis, the ones that happen a long ways away and travel, and we have many hours to prepare,” said Boldt.
“But if we had an earthquake that lasted a very long duration, that’s your signal to move inland, if it happens here, because you might not have much time to react. If there’s an earthquake here and the tsunami hits in 10 or 20 minutes, there wouldn’t be enough time for a warning.”
The West Coast and Alaska Tsunami Warning Center is located in Palmer, AK. It monitors earthquakes world-wide and determines if a tsunami has been generated which may affect the U.S. West Coast. All West Coast tsunami warnings, advisories, watches and informational statements are issued by this warning center, said Boldt.
“It also looks at the Atlantic and the East Coast and the Caribbean since the event in Sumatra (southeast Asia tsunami in 2004). Now the warning center is open 24 hours a day since the Sumatra event. There is a place on the Web page to get signed up for information, the “tsunami watcher,” and you can receive e-mails and text alerts.”
The website for the center is http://wcatwc.arh.noaa.gov/.
The Pacific Tsunami Warning Center is in Hawaii, but it provides warnings for the ocean and the islands.
“The local National Weather Service is the middle guy; we’re getting that information, relaying it to the public, activating emergency alert systems, taking part in conference calls with the warning center every couple of hours, and get local information,” said Boldt.
Boldt also spoke of the DART (Deep-ocean Assessment and Reporting of Tsunamis) warning devices, which are buoys put out across the oceans to detect tsunamis.
“It’s a simple buoy floating on the surface, tethered to the bottom, and relaying information to satellites and then to the warning sensors. The sensor is lying in the ocean to detect a change in the waves. A tsunami wave is the entire depth of the ocean. Normal waves we see every day, it’s just the wind blowing on the top of the waves. The tsunami wave is changing the entire ocean.
“It can detect something as the tsunami passes the buoy; it passes information at that point. It can detect a tsunami that is one centimeter. Most of the time if you’re in a boat in deep water on a ship or boat, you wouldn’t detect it. They are in very deep ocean water – two and a half mile- or maybe four- mile deep ocean water, most will be 200, 300, 400 miles off our coast, and that’s important.
“Most are around the perimeter where earthquakes happen, the Pacific Rim. It’s really important the buoys are near Japan, because when the buoys there are hit, we get the information and can determine what’s going to happen when that tsunami gets here to our coast,” Boldt said.
In 2001 there were six tsunami buoys across the Pacific Ocean. Today there are 39 for the Pacific, Atlantic and Caribbean. Boldt’s presentation included a chart that showed the monitoring of the buoy placements. He said that occasionally one will malfunction because of the rough environment, and it will be a red color to indicate that it’s not working. “The Aleutian Islands (a chain of rugged volcanic islands of southwest Alaska that separate the Bering Sea from the Pacific Ocean) are very critical, and monitoring the buoys would give us time to prepare in case of an earthquake and tsunami,” he said.
“If there is a near-shore event, off the Oregon coast, the buoys warn the people in the western Pacific. The closest buoy to us is about 200 nautical miles southwest of Los Angeles. You can go online and watch the buoys in real time for a demonstration.”
Charts show the origination point of the tsunami, and what the wave height will be as it crosses the ocean. Boldt said there is a natural trench across the ocean that funnels the ocean toward Crescent City.
“The models show the height of the waves that might be expected, and also the travel time of the tsunami, to indicate when it might hit. Everyone is fixated on arrival times. Don’t do that,” Boldt said.
“Arrival times just mean the start, and typically not a lot happens at first. The real action happens many hours later, and that’s when people get in trouble. It’s tough for people to be out at sea, they know the arrival time, and ask why they can’t just come back in. It could be four or eight hours later when the big waves hit – major problems at that point.”
“Definitions include: informational statement – there’s been an earthquake and we’re still evaluating things. Later, a decision is made to issue a watch, similar to a weather event, such as a big rainstorm. We put out a watch for flash flooding potential. It may impact later and could be upgraded. The watch is the first indication we could have a tsunami. It’s not that common for it to be downgraded. The next step is issuing an advisory for a smaller event up to three feet or so, or a warning, that would be over one meter. The emergency alert system is activated in a watch. The advisory is more for harbors and marinas for surge problems.
“Our office is in Oxnard, and we have weather warning responsibility for Ventura, Los Angeles, Santa Barbara and San Luis Obispo counties. That’s what we do 24/7 every day of the year. We put information on our Web site regarding event advisories, warnings, impacts, concerns, arrival times.” Information, Weather.gov/LosAngeles.
“We use the weather radio system – 162.4 and 162.5 MHz radio frequency. We tone-alarm the weather radios and radio and TV stations monitor and broadcast it. Having a weather radio is a good part of preparedness,” said Boldt.
Boldt stated that at Port San Luis near Morrow Bay, the tide buoys monitor the ocean. In Santa Barbara, the first indications of the recent Japan tsunami came at low tide. The event lasted over four days as registered by the buoys.
“A series of waves doesn’t mean that’s the time of the largest waves, and they can last many hours and days. We don’t give the all-clear, that is up to coastal officials to do,” he said.
“There may be no warning for a local earthquake and tsunami. These are the warning signals – if you feel the earthquake when you’re at the beach, or you see unusual wave behavior, such as water pulling back, or you might hear a loud roar from the ocean.”
Sheriff’s Department presentation –
Carriles of the Marina Sheriff’s station noted that small tsunamis can cause damage.
“In the morning, at 8:32 a.m., we didn’t see anything significant,” he said. “At 9 a.m. we started seeing something, but it wasn’t until about eight hours later that we had our most significant change in the Marina. We started seeing the surge come up about 28 to 30 inches in 30 minutes. Thirty minutes later, it dropped. All of that water movement in the harbor can cause damage.
“The boats are tied up, but the water movement puts significant stress on the lines. Fortunately, we didn’t have any significant damage. Our concern is also for people on the beaches and boats,” he said.
Carriles showed a chart of a mock-up for the tsunami inundation zone. It is based on the projected maximum run-up of 42 feet, and it reaches to the Los Angeles Police Department Pacific Station area (at Culver Boulevard and Centinela Avenue) in Del Rey.
He said the sheriff’s department gets its information directly from NOAA on teletype, and whether it’s advisory or a watch or warning.
“Once the tsunami has been generated, our emergency operations bureau will get notification, and they’ll assign people and monitor what’s happening. We monitor what’s happening in other areas, such as Crescent City, if something is coming down from Alaska, or Hawaii after the Japan event. We had time to figure out what we were going to do and what steps to take.”
“We talked about locally generated tsunamis. Basically, if it’s strong enough to knock you off your feet, go to higher ground. If we have an 8.5 earthquake that lasts 20 seconds, one or two minutes, we have to worry about a tsunami, but think about what is going to happen to our buildings, freeways and roads.
“There are a lot of things we have to consider, especially with a locally-generated tsunami. With a teletsunami ( a tsunami generated at a far-away source) we can have six to 11 hours of notice to get the word out. If it’s locally generated, if our boat isn’t already off-shore, they’re coming in and we have to evacuate our headquarters, and make notices to people via PA (public announcement) system and everything else,” Carriles said.
“We are looking at AlertLA, which is reverse 911. Business owners and land-line users will already receive that. The issue is people on boats, even residents, don’t have land-lines. You can register your location with a cell phone if you’re a business owner here but live somewhere else like Simi Valley.
“This is a recreational community and we need to address how to notify them. Helicopters, siren systems are options. Sirens are great if everyone knows what it means. We are pushing for the capability of giving instructions by voice over a large distance and these methods would work for other disasters,” Carriles said.
“We are also pushing the CERT (Community Emergency Response Team) program. We train the community to help. We have over 8,000 people here, and two police cars and a boat at this station. We’ll do our best getting the word out. We have the fire department, Baywatch, but the community will also have to rely on itself for help.
“Regarding evacuation routes, there are signs around the Marina and Venice. If you’re in a building, evacuate vertically and get higher in the building. Trying to get that many people out of the area could just endanger them. Marina del Rey and Venice would be pretty much underwater.”
Education is critical. Having a plan and an evacuation route for employees or family is important rather than waiting until something happens. CERT training educates about disaster preparedness, he emphasized.
Carriles said the department is looking for a local venue to have a CERT training event. We can train a lot of people, but six months later it could be a whole new group of people.
Carriles suggested that marina operators and business operators train their employees, dock masters and maintenance people so that someone will be in charge.
“If we get something that generates a 42-foot tsunami, we’ll have a lot more issues, in my opinion, with our buildings and everything else. If it’s six meters or a two-meter tsunami and a high tide, we’ll get some flooding. A two-story building might be okay but there’s no guarantee. We have good earthquake standards but there are other issues,” he said.
“Our plan is 100 fathoms – 600 feet, or four or five miles going out in the ocean.”
Regarding a question about outgoing traffic using both lanes to evacuate, Carriles said that in the event of an emergency, Washington Boulevard traffic would likely be one-way on both sides, Lincoln Boulevard at a certain point would be one-way, and the 90 Freeway would be one-way. He said the 90 Freeway would be above the projected inundation zone. For a 42-foot locally generated tsunami, there are concerns about structures and roadways coming down, he said. Information, http://watchthewater.org.