Tsunami awareness requires more than just signs like this one in Pacifica; government support for public education and scientific research is crucial too. Photo courtesy Anita Hart of Flickr under Creative Commons license

After the Sumatra earthquake and tsunami of 2004, the U.S. government quickly expanded funding for the right things. These included the network of DART (Deep-ocean Assessment and Reporting of Tsunamis) seafloor sensors, coastal signage, inundation maps, and procedures to be presented at coastal towns. By 2011, the tsunami program had done a lot of good, and when the giant Tohoku earthquake sent tsunamis across the Pacific, the DART network did its job, emergency workers did theirs, and citizens had a clear idea of what would happen when waves reached America.

What now? Most people would probably agree that a useful, well-operating program should be maintained. When the White House proposed to reduce its funding next year, voices of dismay were easy to find. Environmentalist Jeff Ruch said, "This is like a homeowner trying to economize by disconnecting the smoke detector." The Mercury News editors thundered, "Nobody wants to find out what an unannounced tsunami might do to America's shores." I think those responses are over the top. More realistic was a quote from an emergency management pro: "Preparedness and public education is perishable. People need to be reminded. It's just like earthquakes."

The people running the program didn't seem as upset, and the reported details of the plan appeared to be consistent with an agency tapering off from buildup to maintenance. Still, beneath the concern was a bit of knowledge that's deeply ingrained among earthquake scientists, especially those in California: awareness is short-lived, peaking with significant events and then declining until the next catastrophe. History tells them so.

Early Californians were shaken by earthquakes often. Just since statehood, the Bay Area had damaging quakes (magnitude 6 and greater) in 1861, 1864, 1865, 1866, 1868, 1870, 1881, 1884, 1889, 1890, 1892, 1897, 1898, and then 1906. (See them in this timeline from California Watch.) Historian Stephen Tobriner has shown that 19th-century San Francisco architects designed their structures in full awareness of earthquakes, although building codes did not reflect the need. The 1906 earthquake was followed by strenuous denial of the hazard on the part of officials and business interests. Building codes did not begin to change until after the Santa Barbara quake of 1925, and the Long Beach quake of 1933 led to the Field Act mandating earthquake-resistant school buildings. Since then, scientists and the state have generally had a good relationship in terms of codes and regulations.

Public awareness and mass preparation have been more episodic. In this part of California, large earthquakes virtually disappeared after 1906 until the late 1970s. In the meantime, populations multiplied and memories faded. Since then the tectonic system has been expressing the growing strain that will inevitably spawn the next Big One. It's no wonder that earthquake scientists are staying vigilant.

There is a half-life in public awareness, analogous to the half-life of a radioactive isotope, such that measures of concern peak after an event, soon drop, and then taper off more gradually to a background level. (The web-link service bit.ly has documented its own version of this half-life, and marketing researchers incorporate half-life in models of advertising.) Old-timers in seismology can recount waves of government support for their science that crested in the 1960s (in the Cold War context), the 1970s (after the 1971 Whittier quake) and again after our own wake-up event, 1989's Loma Prieta quake. Volcanologists can tell similar stories about volcano monitoring. The weather service has its ups and downs of government favor, too.

Will tsunami researchers have to go through cycles like this before they reach steady levels of support? Undoubtedly. A key task is to raise that background level of awareness. The road signs and inundation models and DART networks have a built-in robustness that assures them a lasting effect beyond the annual budget cycle. It's up to the rest of us to keep paying attention.

Ghost forest on Washington state's Copalis River during a very high fair-weather tide in December 1997. Photo courtesy of the USGS public domain

If a megathrust earthquake struck the modern world, most of us would know about it within seconds. Bill Steele, Director of Information Services at the Pacific Northwest Seismic Network, would get a detailed account from an extensive array of seismometers located around the globe. Regular citizens would probably get an email, tweet, or Facebook note from a friend.

But what if the quake hit hundreds of years ago? How were scientists able to determine that a Cascadia Subduction Zone megathrust trembler hit sometime between 9:00 and 10:00 p.m. on January 26, 1700?

The story starts in the 1980s when geologist Brian Atwater, dendrochronologist David Yamaguchi, and others began to investigate the Pacific coast of Oregon and Washington. Traveling by foot and boat through the region’s many bays and river mouths, the scientists examined thousands of dead western red cedar and Sitka spruce. The trees had not fallen to the ground but stuck upright out of the sand in great groves, known as ghost forests.

Intriguingly, James Graham Cooper, a naturalist living on the Washington coast in 1853-1854, had noticed the dead trees, too. He thought they had died slowly, sinking into quicksand. Atwater, however, knew differently. When a magnitude 9.5 earthquake hit Chile in 1960, coastal marshes had dropped several feet, allowing sea water to flow in and quickly kill the trees.

Because the spruce and cedar still stood in place, Atwater and Yamaguchi realized they had a clock that would tell precisely when the trees died. All they had to do was look at the trees’ growth rings. Those rings would reveal how the trees had lived and when they had died.

Tree ring analysis, or dendrochonology, is based on the fact that trees add new material each year: early, lighter-colored cells followed by darker cells. Each set is known as a tree, annual, or growth ring. Width depends on the climatic conditions with wider rings in a good growing season.

Yamaguchi found that the trees had wide rings right up until the time they died. This indicated that disease had not killed the trees. He and other researchers then compared the rings of the dead trees with those living nearby. These trees spanned nearly a thousand years of time, from 993 to 1986. Using this data, they tried to match the growth rings of the living trees with the growth ring of the dead trees. A match would tell when the ghost forest trees died.

They had a problem, though. Erosion of the tree’s trunks had obliterated the final rings. Fortunately, in 1996, they dug up eight stumps whose roots had not decayed. In all but one case the rings showed the trees had died between August 1699 and May 1700. Narrowing the timing down to January 26 required another line of evidence, and the assistance of colleagues and documents from Japan.

Proposed tower and berm structure by Ronald Kasprisin. Image courtesy of the Washington Emergency Management Division.

CAMP MURRAY, WASHINGTON- When natural disaster strikes, most of us instinctively run for the hills. But what if you live in the flats, and can't outrun or even out-drive a fast-approaching tsunami wave?

The low-lying coast on the west coast of Washington state is one such region. Residents face both the risk of a major earthquake from the Cascadia fault, and tsunami waves predicted to pummel the shore only 30-40 minutes after the quake. John Schelling, Earthquake Program Manager at the Washington State Emergency Management Division, claims that when a tsunami is approaching, residents need to be prepared to evacuate—vertically.

Schelling worked with a team of engineers to plan a series of towers, buildings and berms to provide a vertical escape option that is easily accessible and can withstand the massive force of a tsunami. The proposal, dubbed "Project Safe Haven," is well underway in Washington's coastal communities, including Ocean Shores and Westport where community members have come together to figure out what “heading for higher ground” will look like for them.

“The community members themselves have been the drivers for a lot of the effort that’s gone on in the Safe Haven Project,” says Schelling. “We’ve tried to make sure all of these are multipurpose so that people interact with them on a daily basis.”

But there will be much more physics and engineering going into these buildings than meets the eye.

Locations on Washington coast for proposed vertical evacuation structures. Image courtesy of the Washington Emergency Management Division.

“The structures themselves have to be designed to withstand at least a magnitude 9 earthquake,” says Schelling. “You’re talking about a significant amount of geotechnical engineering and analysis to make sure the footings that are placed support the weight of the structure, as well as account for the forces that are coming.”

Designing a structure to withstand an earthquake of that size is a task in itself, but these buildings and towers will also then need to withstand the force of the approaching tsunami wave. The engineering answer to this challenge? “The ground floor would be sacrificial, the walls are designed to wash away, and allow water to flow in and out,” says Schelling. Meanwhile, the top floors, where the evacuees would be gathered, are left intact.

It’s a different design concept than berms which are essentially small, hollow hills that can be easily accessed, including by those people who may have trouble quickly climbing to safety in towers or buildings. These structures will be strategically placed throughout the communities most vulnerable to a tsunami. The goal is not only to get as many people to safety as possible; it’s to get as many people to safety as quickly as possible.

While the berms would have the largest foot print on the landscape, they will be able to hold anywhere from 100 to 10,000 people above the water. The outer mound will be constructed from soil to provide a natural slope that can easily be climbed. Schelling says the inside will be a “reinforced concrete core” to keep the berm from collapsing during an earthquake and steady as the tsunami waves hit the coast.

The other benefit to berms is that the mound of earth, similar to the one in Gasworks Park in Seattle, can provide safety without looking too man-made and disrupting the natural environment. “It’s designed to blend in and provide a nice aesthetic to the natural and built environment that people love about the coast,” says Schelling.

For these safe havens, the sky is the limit.

Additional Links

• Project Safe Haven: Tsunami Vertical Evacuation on the Washington Coast on Facebook
• Washington Military Department: Emergency Management Division's Tsunami Evacuation Tips

Colette Kent, intern at KCTS 9 and student at George Washington University, contributed to this blog.

Courtesy of NASA

On March 12, a one-foot tidal wave was filmed as it slowly surged across the San Francisco Bay. The wave traveling 5000 miles from Japan started out as a 23-foot tsunami off the Japanese coast. It was created by a devastating earthquake with a magnitude of 9.0. The earthquake was the largest earthquake in Japan’s history and the fourth largest earthquake since 1900. It shifted the planet’s axis and opened a rift that moved Japan closer to the United States by thirteen feet.

We were lucky to have such a slight nudge from such a devastating natural disaster. Crescent City was not so lucky. Six to eight foot surges hit the harbor of Crescent City creating flooding, splintered docks, and damage to boats and marinas alike.

Crescent City’s claim to fame is it the only town in the continental US where a tsunami has killed residents. On March 28, 1964, a 21-foot tsunami wave created by a earthquake in nearby Alaska surged into the town of 7,500 doing extensive damage and killing 11 people. Underwater topography can tunnel these massive waves to direct them towards a certain point, which increases the power by centralizing their force. Such was the case with the wave that hit Crescent City; the underwater topography leading to Crescent City created a funnel for the wave in 1964.

With such a powerful wave, it is a blessing that more people were not killed. Early sirens warned of the wave and many residents retreated to higher ground. UGGS put out a report in 2005 of how to survive a tsunami taking much information from the survivors of Tsunamis in Chile, Hawaii and Japan. From their extensive research, the following points were given:

• Many will survive the earthquake that will later trigger a tsunami

• Look for natural warnings; An earthquake or rise and fall of coastal waters may serve as an early warning as well as wildlife heading for higher ground

• Listen for official warnings; Take sirens and evacuation notices seriously

• There is usually not just one wave; Generally small waves are then followed by higher intensity waves

• Head for higher ground and stay put; It may take several hours for the Tsunami force wave to hit

• Abandon belongings; Many people died concerning themselves with belonging rather than heading to higher ground

• Roads may not be an escape route; They might be made impassable by earthquakes or earlier waves

• If getting to higher ground is not an option:
Go to an upper floor or roof of a building; Climb a tree; If you are near wave, find something that can act as a raft

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^{The tsunami of March 11 broke docks and damaged boats in Santa Cruz Harbor. Most earthquake-generated tsunamis in this part of California will cause similar levels of damage. Photo courtesy Sequoia Hughes of Flickr under Creative Commons license.}

Last week the Bay Area got a tiny taste of Japan's seismic disaster when tsunami waves stirred our waters, a giant agitating the San Francisco Bay and coast with a flick of its pinky. The waves we saw overwhelming the east coast of Honshu were attenuated to small surges here at the opposite side of the Pacific Ocean.

In central California, we will always have good warning of these big seismic tsunamis because they are not created nearby. Our tectonic setting is not conducive to Japan or Sumatra-style tsunamis. But I said seismic tsunamis, the ones that earthquakes cause. There are two other kinds that mean you should always practice tsunami awareness when you're at the beach. And National Tsunami Awareness Week, scheduled by purest coincidence for next week, is a good occasion to train yourself and your family.

Standard tsunami awareness is pretty simple, simple enough to put on a sign that says, "In case of earthquake, go to high ground or inland."

_{Photo courtesy Bruce Manchon, all rights reserved}

That refers to an earthquake that you feel, not one you hear about on the radio. I can be a little more specific. Don't worry about small earthquakes, namely the short, sharp shocks we feel often around here. Worry about a long-lasting earthquake, one with slow rhythms. If one of those happens while you're at the beach, look—you want to leave anyway, because a large earthquake like that may mean trouble at home. If the sea starts acting strange, do what the sign says, period. Otherwise, follow your usual earthquake protocol: Get away without dawdling, drive warily with your radio on, remember your family plan, use your phone no more than absolutely necessary.

The tsunamis that arrive from distant quakes, or teletsunamis, come with several hours of warning. The nearest earthquake faults that could send a damaging tsunami our way—subduction zones—are off northernmost California, part of the Cascadia seismic zone that stretches up the Oregon and Washington coast into Canada. A tsunami arising from a magnitude-8 or larger event up there would arrive here at least a couple hours later. Tsunamis from major earthquakes in Alaska, far eastern Russia, Japan and the Philippines will give us much longer warning times. There are enough people on a typical beach, with phones and text devices and radios, that you should be able to count on sufficient warning even for a Cascadia event. In addition, local emergency responders will be out in person to warn beachgoers. (If you're on the beach alone, be more alert.)

If you hear about an approaching tsunami, I must advise you: don't be irresponsible and rush to the beach. We're all intrigued by geological phenomena, and every red-blooded geologist has "witness a tsunami" on his or her geological bucket list. But remember the person taking pictures at Crescent City (a town also ravaged by a tsunami from the 1964 Alaska earthquake) who was washed out to sea. Think about the surfers who wandered around Santa Cruz Harbor, risking themselves and worrying others, as the waters rushed in and out.

However, if you choose to ignore my advice, then you should do as I wish I could have done, and proceed in a responsible manner to a safe place high above the water, obeying authorities, not congesting emergency escape routes, prepared for the worst. UC Santa Cruz geologist Christie Rowe did that and recorded the tsunami's arrival. She adds, "I would advise people not to panic, to check the West Coast Tsunami Warning Center website and select a vantage point well above the predicted wave height."

But not every tsunami is a seismic tsunami. Two other kinds of tsunamis, not monitored by dedicated networks, have a chance of happening somewhere in the world during the average lifetime: landslide and impact tsunamis. A landslide tsunami, caused by large mass movements into or beneath the sea, is quite plausible along our steep coasts and rugged offshore seafloors. Be wary of one even after a relatively small local quake. An impact tsunami, caused by an object from space crashing into the ocean, has no upper size limit and no preferred location. The odds are small but every beach in the world, ours included, faces the risk. So be like a sailor and always keep your weather eye out.

Learn more:
California tsunami information
National Tsunami Awareness Week
tsunami.gov
West Coast/Alaska Tsunami Warning Center

And check out QUEST's story "Scary Tsunamis":

QUEST on KQED Public Media.

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It feels like the world is still shaking from the earthquake and ensuing tsunami that hit northern Japan on Friday. The 8.9 magnitude quake created enormous waves of water, which moved quickly through the ocean and hit the coast of Japan with waves that in some areas were over 10 feet high. This animation shows how earthquakes give rise to tsunamis. When tsunamis hit shore, they can carry with them sediment that they’ve picked up from the bottom of the ocean. This sediment differs from the sediment close to shore, leaving a long-term record of the tsunami’s occurrence.

Paleontologists can look at the layers of sediment along the coast and see records of past tsunamis. They can also see that before tsunamis occur, the land along the coast often starts to subside, as one tectonic plate slips underneath another. The clue that tells paleontologists that the coastline tilts before an earthquake is a group of tiny marine organisms, called foraminifera. By studying these organisms in the sediment along the shore of the West Coast, scientists can learn how frequently tsunamis occurred here in the past, and whether we can predict a big quake in the future.

The tiny marine organisms in the sediment are called foraminifera, or forams for short. They are protists—neither animals nor plants, protists are a grab bag of simple organisms that includes amoebas, seaweeds, and single-celled algae. Forams are unicellular, and they build a shell, called a test, out of calcium carbonate. The test has little opening from which pseudopods—thin strands of the cell’s cytoplasm—protrude. The pseudopods help the forams move around. However, it is the calcium carbonate tests that make forams so useful as records of geological events.

The tests of foraminifera are often well preserved in marine sediment, as fossils. Forams evolve relatively quickly, so micropaleontologists (folks who study tiny fossils) can determine the age of the sediment by identifying the species of foram that is preserved. Also, each species of foram can survive only in a narrow range of environmental conditions. If the water is too salty, a given species can’t survive; if the water is too fresh, that species won’t survive either. The salinity of the water has to be just right. This means that micropaleontologists can use foram fossils to estimate the salinity of the water in the past. (For similar reasons, forams are also good indicators of the proximity of oil deposits, and a good proxy for past climates.)

A few years ago, UC Berkeley Professor Emeritus Jere Lipps and a few colleagues, including Dalhousie University professor David Scott, travelled along the coast from Alaska to Baja, taking cores of coastal sediment along the way. They found that several years before a big earthquake and tsunami, the foram composition in the sediment changed slightly. The forams shifted from species that live in very slightly salty water to species that live in water that is even saltier. This is a sign that the land had begun to tilt downward towards the ocean.

The Pacific plate is slowly sliding underneath the North American plate. But the plates stick together, and the edge of the North American plate gets pulled down slightly along with the Pacific plate. Suddenly, the plates will un-stick; the North American plate will release and move upwards again, and the Pacific plate will slide underneath. This kind if quake is called a megathrust earthquake. Dr. Lipps and his colleagues found that there have been three megathrust earthquakes, preceded by a tilt in the coastline, over the past 3000 years.

Forams are good measurements of past coastline tilt. But to measure coastlines in real time today, scientists can deploy seismometers. By placing seismometers in areas that have undergone a pre-earthquake tilt in the past, we may be able to detect early warning signs of potentially destructive megathrust earthquakes and resultant tsunamis.

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The Great Wave off Kanagawa is often mistakenly associated with the Tsunami.

"If a tree falls in a forest and no one is around to hear it, does it make a sound?"

The philosopher George Berkeley posed this philosophical question and a quick internet search found a somewhat scientific answer in an 1894 issue of Scientific American. There they wrote: "Sound is vibration, transmitted to our senses through the mechanism of the ear, and recognized as sound only at our nerve centers. The falling of the tree or any other disturbance will produce vibration of the air. If there be no ears to hear, there will be no sound."

Maybe sometimes vibrations are heard much later, only when the right person is listening.

On January 26, 1700, at about 9:00 p.m. Pacific Standard Time one of the largest earthquakes ever to strike the Pacific Northwest rumbled across the Cascadia Subduction Zone. This massive earthquake sent a giant 33 foot high tsunami crashing onto shore, inundating the quiet coastline. While there is no written account describing the earthquake, tsunami or consequential damage, the devastation was enormous.

So wait. If there was no written record, how can we know the exact time and date when the tsunami struck? How can we know how big it was or what kind of damage it did? It took some digging and an impressive bit of scientific detective work by geologist Brian Atwater. First scientists discovered an unusual layer of sand in a marsh area that left a clue that a wave had struck, taken sand from offshore and brought it far inland. The scientists were able to date this thin sand deposit to around 1700, plus or minus 25 to 50 years. Then through tree-ring dating they were able to narrow that down to within five or ten years. Further study of tree roots narrowed it down even further to winter, 1700. Then investigators went to Japan and checked for evidence of a tsunami during that time. They looked for one which did not have a known earthquake associated with it. These were known as “orphan tsunami." There, in the records from 1700, was a tsunami the struck Japan, a wave that had the right pattern, right size, and was generated at the same place, the Cascadia Subduction Zone all the way on the other side of the Pacific Ocean. January 26, 1700, 9:00 p.m.

Can it happen again. Yes. Are we listening?

Watch the Scary Tsunamis television story online.

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