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.

New instruments hook to the underwater lab.
Credit: David Fierstein © 2005 MBARI

We heard about the Monterey Bay Aquarium Research Institute's new underwater laboratory in a radio story last fall. When that story aired, the lab (known as the Monterey Accelerated Research System, or MARS) was just getting going, with lots of neat experiments planned. Now, few of those have become a reality.

In case you missed the first story, the MARS is essentially an underwater data hub, perched on the ocean floor almost 3,000 feet below the surface of Monterey Bay. A 32-mile cable connects the system to land, acting as a power cord and data link. Several "underwater extension cords" allow a variety of instruments to plug into the hub, getting power from land and sending back data via the cable. That constant connection is a big step forward in undersea science; without it, researchers have had to use boats to stay physically close to their instruments (something hard to do for very long), or have sent the instruments off on their own, relying on batteries to keep them running and collecting data.

Until late February, earthquake scientists at the UC Berkeley Seismological Laboratory had been using that second method with their seafloor seismic station, the Monterey Ocean Bottom Broadband (MOBB). "We had to wait three months to even know if the instruments were alive," said Barbara Romanowicz, the lab's director. But the MOBB is now plugged in to the MARS system, and is transmitting its information about earthquakes in real-time.

That new stream of information could be especially valuable in California, because the MOBB provides a unique view of the main fault system, the San Andreas, which runs along the Northern California coast. Most seismometers are land-based, and therefore positioned on the east side of the fault. The MOBB is on the west side of the fault, offering a helpful perspective on the fault's shifts and shakes.

The researchers hope that the MOBB's new stream of real-time data will improve their earthquake models, and perhaps eventually help provide early warnings about impending quakes (for more on that topic, see the TV story, Earthquakes: Breaking New Ground).

The MOBB is just one instrument using the MARS hub. A tool that uses sound waves to track fish is currently attached, and within the next six months you can expect to see a robotic DNA lab and a robot that crawls along the seafloor, collecting data on animals that live in the mud.

I met Mary Lou Zoback out at the Fremont Bart station, which sits right on top of the Hayward Fault. She pointed out cracks in the parking lot from the creeping fault. Zoback is a geophysicist who worked 28 years at the U.S. Geological Survey and who has done catastrophe modeling of risky residential buildings. Her company estimates that a 6.8 quake, or bigger, on the Hayward Fault could cause a disaster on par with Hurricane Katrina, causing 168 billion dollars in damage and leaving at least 200,000 homeless.

A number of public buildings in the east bay are undergoing retrofitting to make them more structurally sound. Area hospitals have until 2013 to meet seismic safety standards. There is a state inventory of public schools prone to collapse in a major quake, but no such list exists for private schools. And retrofitting standards for risky residences are confusing. I talked with Jim Cook, of Bay Area Retrofit. He says existing codes are unclear and there really is no specific licensing for seismic home retrofitters. Cook has been fighting local governments for years to improve seismic safety standards.

Homeowners can have their home evaluated but what if you are a renter? Many apartments and condos can collapse in earthquakes because they have parking or open commercial space on the first floor making this story weak or "soft." According to the Association of Bay Area Governments Earthquake and Hazards Program, soft-story apartment buildings were responsible for about two-thirds of the 46,000 uninhabitable housing units in the 1991 Northridge earthquake. In the Bay Area, unreinforced masonry (older buildings constructed of brick, stone or cement blocks) continues to be a threat.

The thought of a big earthquake is scary enough, never mind the chaos that can happen in the aftermath. But the damage from a large earthquake has repercussions that can last for a very long time. We can still see the scars from the 1989 Loma Prieta earthquake. Downtown Santa Cruz is not yet fully rebuilt and retrofitting continues on the Bay Bridge. We can prevent a lot of damage up front by shoring up our buildings and creating a family disaster plan and an earthquake kit. The Hayward Earthquake Alliance has put together some really helpful information on how to prepare for a major quake.

Listen to the Hayward Fault Radio Report and view the recent QUEST TV segment on the fault online.

So we know – or should know – the seismic risks of living in one of the most vibrant, diverse places in the U.S. Short of leaving the region, what can we do?

Well, one of the most illuminating things about working on this story for me was learning a bit about retrofitting one’s home to make it withstand the lateral and vertical forces that accompany a strong earthquake. In short, you need to build shear walls – made of reinforced plywood and shear transfer ties – and bolt them to the walls in the foundation of your house. Suprisingly, there are no official codes as to what constitutes a proper seismic retrofit of a residential unit in California, nor is there a dearth of licensed contractors who will offer quotes and purport to retrofit your home but without any standards in place, homeowners are often at a loss to evaluate the quality of the retrofit which can easily exceed ten thousand dollars, depending on the size of the home and its location. Still, homeowners can avail themselves of a few retrofit resources online, such as Plan Set A, a guideline for retrofitting one's home that has been approved by building departments of several Bay Area municipalities such as Oakland and Hayward. Also on the Association of Bay Area Government's web site is a set of schematics illustrating shear wall construction. If you are interested in retrofitting your home, you should get quotes from several contractors, consult your city's building department to inquire about permits and possibly consult a structural engineer to perform a building analysis on your home.

If you're like me, though, and don’t own a home but want to prepare for "the big one," it's imperative to get an earthquake survival kit. The sells earthquake survival kits but why not make your own, provided that it has water, first aid supplies, a flashlight, food rations and other essentials for you to survive 72 hours while waiting for emergency help. If you want to make your own kit, try the USGS, the city and county of San Francisco, or helpful suggestions from the San Francisco Chronicle and LA Times.

Living in earthquake country, it pays to be vigilant. I applaud the 1868 Hayward Earthquake Alliance, a consortium of agencies that are raising awareness of the risk posed by the Hayward fault with a series of events aimed at educating the public about the importance of preparedness, including a city-wide drill in San Francisco on October 21st, the 140th anniversary of the 1868 Hayward earthquake. We may not be able to predict when exactly the next earthquake on the Hayward fault may occur but we can start planning today to mitigate its effects.

For those who aren't familiar with the Hayward fault, check out our this link to the USGS Google Earth tour over the fault.

Hawkins isn't your ordinary astronomer. She began her career in an ordinary way: Ph. D. in Astronomy from UCLA, using mathematical models and computer simulations to give meaning to her observations. Along the way, she began to learn about how ancient people studied the sky. She's worked with us on our Ancient Observatories website, and hosted an equinox webcast from the top of the Mayan pyramid in the ancient astronomical site of Chichen Itza. And she's devoted a considerable amount of time and energy to understanding and appreciating how the knowledge of ancient people complements what modern scientists study today.

Most scientists today don't learn much about ancient knowledge. Observations such as measurements of the sun's movement across glyph-crusted temples don't usually meet the rigorous criteria of the scientific process: observe, create hypothesis, test, reproduce results.

In some instances, ancient people followed similar practices that were very similar to those used by modern scientists, observing things systematically and trying to devise explanations that will result in correct predictions. And sometimes the knowledge they gathered was, in fact, so "scientific" that modern researchers use it in their work today.

Take, for example, the knowledge of the Aymara Indians in Peru. The well-being of these adept weather-watchers was dependent on knowing how to time the planting of their vital potato crop with the arrival of the season's first rains sometime between October and December. They did this by making observations like meteorologists might today. They watched the Pleiades, or Seven Sisters constellation rise each night, and noted how fuzzy or clear it looked in the sky. Fuzziness caused by cirrus clouds high in the sky, meant rains were a ways off, and potato planting should be postponed. A clearly visible set of Sisters meant rains would come soon.

In 2002, Ben Orlove an environmental scientist at UC Davis, published a paper about the accuracy of the Aymara's observations of the Pleiades. It turned out that these ancient observations could be used by modern scientists to discern El Nino patterns in the past. Fascinating, since these measurements were taken long before there was a formal science of meteorology. Ancient knowledge becomes data points in modern research.

Hawkins cited another example: Ruth Ludwin, a seismologist at the University of Washington, has used generations-old folk tales of the Coast Salish Indians to help inform her computer modeling of earthquakes. The tales recount a serpent that knew where and when an earthquake would strike. By adapting location information from the stories into her computer models, Ludwin has found several small faults in the Seattle area that may have been active hundreds of years ago when the stories were created and may still pose a risk to local communities.

"It's interesting that what we call evidence can come in many forms," Hawkins says. "It might be part of a song, or a glyph writing or an artistic piece or a story."

And sometimes the records we keep and the stories we tell have more meaning than we can imagine when we create them.

Robin Marks is a journalist and science writer who current serves as a Multimedia Projects Developer for the Exploratorium in San Francisco, CA.