The Santa Barbara Channel contains unstable underwater cliffs that, if upset by a small earthquake, could produce a tsunami headed for UCSB at over 500 miles per hour.
An underwater landslide in the Santa Barbara Channel could trigger a tsunami that would afford UCSB less than an hour before striking the coast. UCSB’s location on the coast of California makes it susceptible to tsunamis generated in the Pacific Ocean as well as those originating from the Santa Barbara Channel. Massive underwater landslides and earthquakes can initiate tremendous waves of water, known as tsunamis, which can travel across oceans at hundreds of miles an hour. When such a wave meets a shoreline, it transforms from a very long wave to a very high one, and can cause great damage when the force of its water collides with buildings on land. One characteristic of tsunamis that makes them easier to avoid than other natural disasters is that they often originate far away, giving coast-side residents time to evacuate before the wave arrives.
Eighty percent of the world’s tsunamis occur in the Pacific Ocean and can be as frequent as one per month, according to the National Oceanographic and Atmospheric Administration (NOAA). However, not all of those waves are destructive, or even reach inhabited land. Those that are destructive can sometimes be avoided if sufficient warning is given.
Tsunamis, often incorrectly called tidal waves, can also originate in the Santa Barbara Channel and while they may not be as massive as waves from elsewhere in the ocean, they would offer little time for residents to prepare. Mechanical engineering professor Stephen McLean said there would probably be only 20 to 30 minutes of warning for Isla Vista if this should happen.
UCSB residents do have a few reasons to take comfort amid all of this bad news: The UCSB campus has been certified “TsunamiReady” by the NOAA and has a program to address tsunami disasters headed by Larry Parsons, director of environmental health and safety for the NOAA. Should a tsunami approach campus, there are communication systems and plans in place that would direct people to safety.
UCSB was certified TsunamiReady by the NOAA in June 2004. The qualifications for this certification involve geographic location and planning of emergency services.
“We have pretty complete plans for everything from storms to earthquakes and tsunamis,” Parsons said. “We have an emergency operations center and use the same radio system as fire and police.”
The location of the campus is also quite important. While much of the surrounding area is not far above sea level, UCSB itself is 40 to 60 feet above sea level, Parsons said. This fact means that it would actually be safer to stay on campus if a tsunami approached with short warning.
“The primary benefit is that we are protected by the bluffs,” Parsons said. “The main plan is to shelter in place. Some of our evacuation routes could be problematic: 217 is in a low-lying area.”
Parsons said that the campus houses about 25,000 people during the day and 3,000 at night. Therefore more emphasis is placed on daytime monitoring, where the staff at environmental health and safety keep track of tsunami warnings.
“We have weather radios that come on automatically if [the tsunami] occurs during the day,” Parsons said.
During evening hours, the tsunami warning radios are monitored by campus police. These authorities would alert people of the disaster and inform them to move to high ground and stay on campus.
“The reason we have the [TsunamiReady certification] is because we have a campus plan and an emergency communication system,” Parsons said.
How a Tsunami Works
A tsunami is not simply a tall version of a normal ocean wave — on the contrary, it is actually flatter, but much longer. A tsunami differs by key characteristics that cause it to be far more destructive than everyday ocean waves, which are usually generated by the wind. One of these characteristics is wavelength, a property that describes how far apart the crests of successive waves are. Normal wind-driven ocean waves have a wavelength of 100-700 feet, which corresponds to a period — or time between crests – of five to 15 seconds.
McLean said that when these waves are traveling on the open ocean, they are classified as deep-water waves because their wavelength is small compared to the depth of the ocean. The waves move across the water near the surface and do not interact with the bottom of the ocean. In other words, it doesn’t really matter how deep the ocean is; the waves would travel in the same way.
Tsunamis differ from these normal deep-water waves in that their wavelength is so long. A tsunami can have a wavelength of over 300 miles and a corresponding period of over half an hour. A wave with such a long wavelength interacts with the bottom of the ocean and is called a shallow-water wave, Mclean said. Because the tsunami interacts with the bottom, it travels at a much greater speed than normal deep-water waves. Tsunamis can reach speeds of 500 miles per hour, the speed of a jet airplane.
McLean said that waves in a pan of water are analogous to waves in the ocean. If someone puts both hands into the pan and shoves the water, a shallow-water wave would be created. This happens because the shove is large compared to the depth of the pan, just as a tsunami wavelength is large compared to the ocean’s depth.
“No matter how deep you think the ocean is, to a tsunami it’s just a little pan of water,” McLean said. “A tsunami is so large — they are caused by movements of the Earth’s crust. Even in the deepest part of the ocean, they feel the bottom.”
The upshot of this is that tsunamis travel quickly and do not disperse as normal waves do. If a tsunami is generated in Alaska, it could easily arrive in Hawaii with enough energy intact to cause massive destruction.
Another peculiar characteristic of tsunami waves is that they have very low height compared to normal waves. A tsunami may only be a few feet high on the open ocean, although hundreds of miles long. A person in a boat would not even notice a tsunami moving right under his feet at 500 miles per hour because the wave has so little height and such a long wavelength, McLean said.
A tsunami becomes dangerous when it approaches land. Even though the wave has little height on the open ocean, as the water gets shallow toward shore, the wave is slowed down by the change in depth. However, it’s difficult to slow down a 300-mile-long wave of water traveling at 500 miles per hour. McLean said the water builds upon itself, creating a wall of water tens to hundreds of feet high that cascades onto land with great force.
“It’s much the same as the waves breaking and coming up the beach, just scaled up 20 to 30 times,” McLean said.
Pacific Tsunami Warning System
The Pacific Ocean is monitored by seven special buoys that record water pressure data and transmit it to two tsunami warning centers, one in Alaska, the other in Hawaii. These buoys were deployed in 1998 where they upgraded an existing system composed of seismic and tide sensors.
The Hawaii center is staffed by five scientists, two of which are on call 24 hours a day, said Delores Clark, an NOAA public affairs officer. If one of the sensors indicates that a tsunami might have occurred, the scientists are alerted immediately via pagers.
“As the water level data starts coming in, that’s when they can tell if a tsunami is coming,” Clark said. “If there is a threat to the Pacific, they will send out a watch or a warning.”
A “warning” indicates that there is very probable danger from a tsunami, whereas a “watch” warns people that there is possible danger from a tsunami. It is sometimes hard for scientists to tell how big a tsunami is because there are not enough sensors to make an accurate judgment, Clark said.
“Until we get more detection gauges, we cannot tell how big a tsunami really is,” Clark said.
Even without knowing the exact size of the wave, there is still much that can be saved by simply knowing that a tsunami is headed for the coast. The warning center alerts each of the 26 Pacific Rim countries that participate in the warning system by various methods.
“The bulletins go out electronically,” Clark said. “Some go through NOAA circuits, but there are a lot of circuits that all countries have access to. One way is fax, another is phone.”
Regardless of how each country is notified of a tsunami, it is each government’s responsibility to make sure people are prepared. Public education is an important part of tsunami preparedness, Clark said.
“Just putting out a warning is not sufficient if the government is not able to alert the public and tell them what to do,” Clark said.
McLean said this was a problem in the recent Indian Ocean tsunami. He said the Indian Ocean does not have monitoring buoys, even though they cost relatively little. If there had been a warning system in place, he said it’s likely that a lot of life could have been saved.
“They were missing two things,” McLean said. “They need sensors to track the movement of the tsunami. They also need a network to let people know about it. There probably was enough time to warn people.”