The New Explorers. Series III; No. 312; Earthquakes

<v Bill Kurtis>There's trouble deep within the earth. <v Bill Kurtis>Tension locked within rock for years suddenly erupts. <v Bill Kurtis>Rocks break. Energy radiates upward. <v Bill Kurtis>An earthquake has begun. <v Bill Kurtis>We'll never be able to prevent them. <v Bill Kurtis>But 1 day we may be able to predict them and help us learn to live <v Bill Kurtis>with this restless earth. <v TV Announcer>Major funding for The New Explorers is provided by Amoco, celebrating

<v TV Announcer>the adventure of scientific discovery for the year 2000 and beyond. <v TV Announcer>Additional funding is made possible by Waste Management Inc., providing <v TV Announcer>recycling and other waste services around the world. <v TV Announcer>And by Duracell, embracing the power of science education, <v TV Announcer>the source of future technology and innovative growth. <v TV Announcer>Duracell, the copper top battery. <v Bill Kurtis>Hello, I'm Bill Kurtis, and this is 1 of the most unusual bridges in the world. <v Bill Kurtis>It spans far more than a shallow stream and actually links 2 enormous <v Bill Kurtis>pieces of the earth's crust. <v Bill Kurtis>At the other end is the North American tectonic plate. <v Bill Kurtis>I'm now standing on the Pacific plate. <v Bill Kurtis>The bridge itself has become an instrument of scientific measurement because as the earth <v Bill Kurtis>moves, so does the bridge. <v Bill Kurtis>It bends. That's why we've come here to central California. <v Bill Kurtis>Scientists have placed more instruments to measure the movement of the Earth <v Bill Kurtis>than any other place in the world, hoping to be able to predict earthquakes.

<v Bill Kurtis>5:04 p.m., October 18th, 1989. <v Bill Kurtis>Without warning, a 45 kilometer stretch of the San Andreas Fault near Loma <v Bill Kurtis>Prieta Mountain breaks loose. <v Bill Kurtis>Releasing a magnitude 7.1 earthquake. <v Man with Walkie>[background chatter of news] It's the on-ramp <v Man with Walkie>to the bridge that has collapsed. And right now, no cars are allowed to use it. <v Bill Kurtis>It's the largest earthquake to hit central California since the 1906 San Francisco <v Bill Kurtis>quake. <v Bill Kurtis>A section of the upper level of the Bay Bridge connecting San Francisco to Oakland <v Bill Kurtis>collapses in the heart of the rush hour. <v Bill Kurtis>Fires erupt throughout the city. <v Bill Kurtis>Firemen are left almost defenseless when the city's water pipes rupture. <v Bill Kurtis>When it's over, 67 people are dead.

<v Bill Kurtis>3757 injured. 1200 homes were lost. <v Bill Kurtis>Property damage is around 6 billion dollars. <v Bill Kurtis>Yet the Loma Prieta quake is considered a modest seismic disturbance. <v Citizen>We are lucky. The geologists say that it can be taken care of. <v Citizen>It will probably never be flat. <v Citizen>We'll have a split-level front yard. <v Bill Kurtis>Why can't we predict earthquakes? <v Bill Kurtis>In this episode, 2 seismologists are trying to do just that. <v Bill Kurtis>One is using clues from the distant past, the other, the most modern technology, <v Bill Kurtis>to try and improve our odds for surviving this kind of devastation. <v Al Lind>The approach that we've taken over the last 10 years [fade out] <v Bill Kurtis>Al Lind is chief seismologist at the United States Geological Survey in Menlo Park, <v Bill Kurtis>California. He's part of a team that's using the latest high-tech equipment to look <v Bill Kurtis>for the slightest movements in the earth.

<v Bill Kurtis>Anything that will tell them an earthquake is on the way. <v Scientist 1>This looks more like a left lateral. <v Scientist 2>Yeah. Put this back together. <v Bill Kurtis>Their goal is to identify the precursors or signs that occur before an <v Bill Kurtis>earthquake hits. So they'll be able to give residents fair warning of what's in store. <v Al Lind>[background chatter]. <v Bill Kurtis>Like his colleagues, Al is on earthquake alerts 24 hours <v Bill Kurtis>a day. He'd better be cited. <v Bill Kurtis>He lives within half a mile of the San Andreas Fault. <v Al Lind>The San Andreas Fault system creates these mountains and creates San Francisco Bay, <v Al Lind>creates the economy of California: the harbors, the agricultural valleys, <v Al Lind>the mountains that catch the snow that makes the water possible. <v Al Lind>California is the product of the San Andreas fault system. <v Bill Kurtis>Since 1812, there have been hundreds of quakes in California, <v Bill Kurtis>12 registering at least 7.0.

<v Bill Kurtis>Because the San Andreas fault system runs straight through the state, there's always <v Bill Kurtis>the potential for an earthquake. <v Bill Kurtis>But studying earthquake prediction is a bit trickier. <v Bill Kurtis>First, the USGS seismologist had to find a site where they could be relatively <v Bill Kurtis>sure there was going to be an earthquake. <v Bill Kurtis>But where? <v Bill Kurtis>Welcome to Parkfield, California, a small town that lies halfway between <v Bill Kurtis>Los Angeles and San Francisco, right on the San Andreas Fault. <v Bill Kurtis>Day to day, there's not a lot going on here, but every 22 years, give or take <v Bill Kurtis>a year, Parkfield has had an earthquake. <v Bill Kurtis>There have been five since 1881, measuring at least 6.0. <v Bill Kurtis>Just the kind of place a seismologist would love. <v Bill Kurtis>So 8 years ago, the USGS teams set up shop here. <v Bill Kurtis>They brought their latest high-tech tools to this low-tech town.

<v Bill Kurtis>They buried creep meters, strainmeters, and seismometers in the ground and promptly <v Bill Kurtis>issued a forecast that a 5.5 to 6.0 earthquake was <v Bill Kurtis>likely to hit Parkfield by 1993. <v Bill Kurtis>They even installed a video camera to look at the San Andreas fault when the earthquake <v Bill Kurtis>happened. They weren't going to miss it. <v Al Lind>It gives us really the first opportunity anywhere in the world to do almost like <v Al Lind>a physics lab experiment to anticipate what's going to happen, to pose hypotheses, <v Al Lind>and then to instrument sort of like we would if we could put the whole thing up on a lab <v Al Lind>bench and wire it up. And it's not quite like that, of course, but it's <v Al Lind>the closest thing we've ever been able to do in earthquake science. <v Al Lind>And that really, you know, it- it if and when things go well, <v Al Lind>that really pushes you ahead a very long ways. <v Al Lind>A little bit of data now and then sort of collected at random is a very hard way to do <v Al Lind>science. A lot of data in 1 place at 1 time, it can make a great leap forward. <v Bill Kurtis>And so with 2 teams in place, one in Parkfield gathering data, the other at Menlo

<v Bill Kurtis>Park analyzing it, the wait for an earthquake began. <v Bill Kurtis>Why do earthquakes happen? <v Bill Kurtis>The answer lies in the theory of plate tectonics. <v Bill Kurtis>Deep within the earth, there's a seething cauldron of heat. <v Bill Kurtis>As it moves toward the surface, it causes the movement of a dozen interlocking plates <v Bill Kurtis>on which the continents ride. <v Bill Kurtis>The boundary between 2 plates is called a fault. <v Bill Kurtis>In a subduction zone, 1 plate moves under another, <v Bill Kurtis>causing coastal uplift and subsidence, a drop in land level elevation. <v Bill Kurtis>In California along the San Andreas Fault, the plates move past each other. <v Bill Kurtis>In both cases, the movement continues until the plates collide at the fault line. <v Bill Kurtis>The rock can't contain the energy and it releases <v Bill Kurtis>an earthquake.

<v Bill Kurtis>Al Lind uses the technology of science to understand earthquakes, <v Bill Kurtis>but long before it was available, the Indians had other ways. <v Bill Kurtis>The tribes who lived in the Pacific Northwest created a rich tradition of earthquake <v Bill Kurtis>mythology. <v Bill Kurtis>They believed in 2 mythical characters named Earthquake and Thunder, <v Bill Kurtis>who ran together shaking and tearing the ground, breaking trees, and disturbing <v Bill Kurtis>the oceans and rivers. <v Bill Kurtis>To the Indians, the earth was flat and rested on water. <v Bill Kurtis>When there was trouble in the world, it was because the earth tilted too far in 1 <v Bill Kurtis>direction. To set it right, they performed a jump dance. <v Bill Kurtis>And as the earth returned to its natural position, it caused an earthquake. <v Bill Kurtis>Passed on from generation to generation, these stories helped them understand and <v Bill Kurtis>explain their world. Although highly symbolic, they seem to be <v Bill Kurtis>actual observations of devastating earthquakes.

<v Gary Carver>[background chatter] <v Bill Kurtis>That's what Gary Carver thinks they are. <v Bill Kurtis>He's a paleoseismologist at Humboldt State University. <v Bill Kurtis>Like the USGS team, he's interested in predicting earthquakes. <v Bill Kurtis>But instead of studying the signs that an earthquake is coming, he's looking for clues <v Bill Kurtis>that 1 has occurred. <v Gary Carver>There's a fault right through here. <v Bill Kurtis>He studies the geologic record left by ancient earthquakes along the Cascadia subduction <v Bill Kurtis>zone that lies under the Pacific Northwest. <v Gary Carver>There's a very wonderful story that was recorded um around the turn of the century <v Gary Carver>by uh an elderly Indian woman, Yurok woman by the name of the Ann of Espoo. <v Gary Carver>Now, this is a remarkable story because it was recorded for <v Gary Carver>many decades, several decades prior to the general recognition in the scientific <v Gary Carver>community that large earthquakes in subduction zones resulted in subsidence. <v Bill Kurtis>There's no historical record of these quakes, but like the Indians, Carver knows <v Bill Kurtis>they've happened. They've left their mark all over the landscape.

<v Bill Kurtis>The evidence is buried in the mud. <v Bill Kurtis>I joined Gary early 1 morning. <v Bill Kurtis>As the tide went out, we went in. <v Bill Kurtis>To the Mad River slough, traveling back in time. <v Bill Kurtis>Well, Gary, what happens in an earthquake in this part of the country? <v Gary Carver>Well, this would be a very interesting place during an earthquake, as best we can tell. <v Gary Carver>This area um would undergo um a good deal of subsidence. <v Gary Carver>In the uh- in the marsh banks here are- are layers of soil that were <v Gary Carver>formed when the surface was above sea level. <v Gary Carver>And they're now submerged below sea level and below layers of mud that were deposited in <v Gary Carver>the bay over them. We believe that these uh layers of soil represent this land surface <v Gary Carver>prior to uh these large subduction zone earthquakes, and that uh during the earthquake, <v Gary Carver>this- this part of the bay, this northern end of Humboldt Bay, uh sinks or subsides <v Gary Carver>on the order of perhaps uh several feet, maybe as much as 6 or 8 feet.

<v Bill Kurtis>But why bother studying an earthquake that may have happened over 300 years ago? <v Bill Kurtis>Because the earthquakes that occurred in subduction zones had the potential to be massive <v Bill Kurtis>quakes. 80 percent of all the world's earthquakes have happened along <v Bill Kurtis>the subduction zones of the Pacific Rim, known as the Ring of Fire. <v Bill Kurtis>The largest recorded quake was in Chile on May 22nd, 1960. <v Bill Kurtis>It was a magnitude 9.5, and its numbers were devastating. <v Bill Kurtis>5000 people died. <v Bill Kurtis>450,000 homes destroyed. 2 million people left homeless. <v Bill Kurtis>Volcanoes erupted in the days that followed. <v Bill Kurtis>6800 miles across the Pacific in Hawaii tidal waves rip the Hilo Harbor <v Bill Kurtis>District apart. And they didn't stop there. <v Bill Kurtis>The waves hit Japan, leaving 150000 people homeless and <v Bill Kurtis>180 dead. Damage was estimated at 50 million dollars. <v Bill Kurtis>The list goes on. Tokyo, 1923.

<v Bill Kurtis>8.0. Russia, 1952. <v Bill Kurtis>8.2. Mexico City, 1985. <v Bill Kurtis>8.3. And closer to home: southcentral Alaska, 1964. <v Bill Kurtis>9.2. The largest recorded quake ever to hit North America. <v Bill Kurtis>The ground shook for almost 4 minutes, triggering landslides in Anchorage and the <v Bill Kurtis>surrounding area. The shaking was so violent train tracks were left twisted <v Bill Kurtis>and broken. <v Bill Kurtis>The earthquake generated tidal waves that wiped out entire stretches of coastline. <v Bill Kurtis>One struck the town of Seward, setting gas tanks on fire. <v Bill Kurtis>The changes in land elevation, a signature of subduction zone quakes, affected <v Bill Kurtis>an area of more than 34000 square miles. <v Bill Kurtis>When it was over, 114 people had died, <v Bill Kurtis>and 3-quarters of a billion dollars worth of property was destroyed. <v Bill Kurtis>Could it happen again in the Pacific Northwest?

<v Bill Kurtis>We hope to find some clues, but it won't be easy. <v Bill Kurtis>I am stuck. [laughs] I'm trying to get out. <v Gary Carver>I think I'm gonna sacrifice- <v Bill Kurtis>Yeah sacrifice the shoe, I can pull it out afterwards. <v Bill Kurtis>Good thing I can-. <v Gary Carver>Oops, now I'm stuck. [both laugh]. <v Bill Kurtis>Well, I think I'll wash those up. <v Bill Kurtis>You know, when I get back. [laughs] <v Bill Kurtis>The shoes will be sacrificed, but we are ready to begin. <v Gary Carver>But you can see here, this is the bottom part, the root section and the stump of what was <v Gary Carver>a big old tree here. This is a casualty of the last big <v Gary Carver>subsidency bit that occurred here in the northern part of Humboldt Bay. <v Gary Carver>That's a sample that consists of wood that was formed over just a short period of time. <v Gary Carver>And we can count the rings from that sample site to the outside of the tree.

<v Gary Carver>So we know the time at which those rings were formed relative to when the tree was <v Gary Carver>killed, which we think was the earthquake. <v Gary Carver>This earthquake, which we hypothesized here, occurred about 300 years ago. <v Bill Kurtis>Well, what a marvelous way to at least look back in time <v Bill Kurtis>about earthquakes. Is there anything that we can learn from this that may help us predict <v Bill Kurtis>when it will come again, perhaps the cycle? <v Gary Carver>The data thus far is not enough to make a conclusive statement about <v Gary Carver>the probability for um future large earthquakes. <v Gary Carver>Certainly, though, we can see here that there's abundant damage that they've occurred in <v Gary Carver>the past. And so we would hypothesize that they would occur in the future again. <v Bill Kurtis>And that's exactly what happened. On April 25th, 1992, <v Bill Kurtis>an earthquake struck the Cape Mendocino area of Humboldt County, California, during a <v Bill Kurtis>festival. <v Bill Kurtis>It wasn't particularly powerful, but it carried the signature tidal waves and coastal <v Bill Kurtis>uplift. What the Indians had experienced and Gary Carver had predicted

<v Bill Kurtis>was finally happening. The Pacific Northwest was having its first subduction <v Bill Kurtis>zone earthquake in recorded history. <v Gary Carver>Prior to this earthquake, 1 of the principal arguments against <v Gary Carver>the subduction zone generating strong earthquakes was the lack of any large earthquake <v Gary Carver>strike record. That argument now seems to be diffused. <v Bill Kurtis>The Cape Mendocino earthquake proved that a subduction zone earthquake could happen in <v Bill Kurtis>the Pacific Northwest. But what does it mean for the potential of a massive quake? <v Bill Kurtis>For now, Gary Carver can only narrow his predictions of when <v Bill Kurtis>to once every 300 years. <v Bill Kurtis>But he continues his search. <v Bill Kurtis>Meanwhile, back in Parkfield, the question of when looked like it was going to be now. <v Bill Kurtis>On October 18th, 1932, a small earthquake struck Middle Mountain near <v Bill Kurtis>Parkfield and set off a wave of excitement.

<v Bill Kurtis>With the hope that it might be the precursor to the large earthquake they'd been waiting <v Bill Kurtis>for, the USGS team went into action. <v Bill Kurtis>A decision was made to issue a warning. <v Bill Kurtis>There was a 37 percent chance of an earthquake hitting Parkfield in the next 72 <v Bill Kurtis>hours. This quiet, sparsely populated community wasn't going <v Bill Kurtis>to stay that way very long. <v Speaker>[music plays] <v Speaker>[background chatter] <v Parkfield Resident>Working with the state government as need be. <v Carl Sankin>I'm Carl Sankin in Parkville- Parkville. Great, I knew I'd do that.

<v Carl Sankin>I'm Carl Sankin in Parkfield, where the San Andreas Fault isn't giving up any secrets <v Carl Sankin>tonight. <v Camera Man>You got a bug in your nose. <v Carl Sankin>What? <v Camera Man>You got a bug in your nose. <v Reporter>Odds of that strong earthquake hitting the Parkfield area by tonight, dropping off with <v Reporter>each passing minute. The deputy director of the State Office of Emergency Services says <v Reporter>nobody promised 100 percent certainty. <v Reporter> <v Bill Kurtis>As soon as I arrived, I took a tour of the Parkfield science lab. <v Bill Kurtis>John Langbein, a member of the USGS team, was my guide. <v Bill Kurtis>Now the experiment is right down there, I see the solar panels. <v John Langbein>That's correct. That's for uh sending the data back to Menlo Park, where we can <v John Langbein>look at it in near real time and get sent back to Menlo Park once <v John Langbein>every 10 minutes. <v Bill Kurtis>The data comes from the instrumentation they buried in 1985, all <v Bill Kurtis>designed to record precursors, clues that an earthquake was coming. <v Bill Kurtis>A creep meter measures the surface slip on a fault, a wire is stretched

<v Bill Kurtis>across the fault between 2 points. <v Bill Kurtis>As the fault moves, the wire stretches. <v Bill Kurtis>The creek meter senses the lengthening of the wire. <v Bill Kurtis>Check me and see if I'm right. We have the fault that's coming right through <v Bill Kurtis>here. Just at right in here. <v John Langbein>Correct. That's correct. <v Bill Kurtis>Then you have strung a wire across the fault- <v John Langbein>That's correct. <v Bill Kurtis>From that point to that point. So that as this side of the fault <v Bill Kurtis>uh goes south, this side's goes this way. <v John Langbein>That's right. <v Bill Kurtis>And you can measure how far the wire stretches. <v John Langbein>That's correct. <v Bill Kurtis>Right? Okay. <v Bill Kurtis>Above ground, another set of instruments measures the overall pattern of change <v Bill Kurtis>in a region. <v Bill Kurtis>The USGS installed a 2-color laser geodimeter. <v Bill Kurtis>A beam of light from the laser positioned on the North American plate is shot across a <v Bill Kurtis>section of the San Andreas Fault to a reflector on the Pacific plate. <v Bill Kurtis>By keeping track of the time it takes for the beam of light to go out to the reflector

<v Bill Kurtis>and return, scientists can calculate the distance between the reflector <v Bill Kurtis>and the laser. Over time, a pattern of movement between the 2 plates <v Bill Kurtis>can be established. It is so sensitive it can detect a change <v Bill Kurtis>in distance as small as 1 millimeter. <v Speaker>[background chatter] <v Bill Kurtis>1 of the first people to get a call was Parkfield's only school teacher Dwayne Ayman. <v Bill Kurtis>A longtime resident, he operates the laser geodimeter. <v Dwayne Ayman>In order to aim this, I've got to uh put reference marks on the wall. <v Dwayne Ayman>So what I'm doing now is lining up with these reference marks to index <v Dwayne Ayman>this in the right spot. <v Dwayne Ayman>Now, this is just a normal rifle scope on here that we look through, <v Dwayne Ayman>and I just watch for the return, and then I fine-tune it to get the return as strong as I <v Dwayne Ayman>can. <v Bill Kurtis>After the smaller earthquake, he was anxious to take measurements to see if there had <v Bill Kurtis>been any changes.

<v Dwayne Ayman>I saw no change on this as far as distances were concerned. <v Dwayne Ayman>I came up just before the earthquake, got a great set of data, <v Dwayne Ayman>came back after the earthquake, took a few more measurements, and they were exactly <v Dwayne Ayman>the same as the measurements I took before the earthquake. <v Bill Kurtis>And so the score, San Andreas Fault, 1. <v Bill Kurtis>Scientists, nothing. <v Bill Kurtis>If there was an earthquake on the way, the high-tech equipment wasn't measuring anything <v Bill Kurtis>yet. <v Bill Kurtis>The next morning in Parkfield, and still no earthquake. <v Dwayne Ayman>Go around the outside of it with your pencil. <v Dwayne Ayman>I like like to tell the kids uh, if somebody's gonna shoot <v Dwayne Ayman>you with a rubber band, do you want him to just stretch a little bit and let go, or do <v Dwayne Ayman>you want him to stretch it a whole bunch and let go? <v Dwayne Ayman>And I look at Parkfield in this section of the fault as a rubber band being stretched a <v Dwayne Ayman>little bit. I look at the southern section of the San Andreas, south of here, <v Dwayne Ayman>as a rubber band that keeps stretching and stretching and stretching. <v Dwayne Ayman>I mean, let's face it, this is good out here. If you can stay out from under the oak

<v Dwayne Ayman>trees and the chimneys, you're probably going to survive it. <v Reporter>There were earthquakes today, but not in Parkfield. <v Reporter>3 smaller ones shook the Yucca Valley [fade out]. <v Bill Kurtis>3 days after the Parkfield earthquake alert began, the USGS team called it off <v Bill Kurtis>and went home. No precursors, no earthquake. <v Bill Kurtis>There would be other small quakes in Parkfield in 1993, but so far, <v Bill Kurtis>no big 1. <v Al Lind>The energy's in the ground. We use lasers to measure the deformation. <v Al Lind>We see the mountains continue to move by one another. <v Al Lind>The energy's not going anywhere. It's there. <v Al Lind>And that's just a question of when it will be released. <v Bill Kurtis>To increase its chances, the team found an additional site to study. <v Bill Kurtis>This 1 is on the Hayward Fault near San Francisco Bay. <v Bill Kurtis>They say there's a 23 percent chance of a 7.0 or larger quake <v Bill Kurtis>within the next 30 years. <v Bill Kurtis>Earthquakes are a grim reminder of nature's destructive force. <v Bill Kurtis>And even though they happen again and again, we still seem surprised.

<v Al Lind>The hardest thing about earthquakes is that they're so infrequent. <v Al Lind>They're so infrequent, you're tempted to ignore them and build poor buildings. <v Al Lind>It's not earthquakes that kill people. It's crummy buildings. <v Bill Kurtis>Although much has been learned about what causes earthquakes, we still don't know how to <v Bill Kurtis>predict them accurately. But it's early. <v Bill Kurtis>Parkfield, Hayward and maybe even Indian legends could help us learn to <v Bill Kurtis>live with them. <v Al Lind>We've come a long ways toward predicting earthquakes in a broad, general <v Al Lind>sense. I suspect in another generation <v Al Lind>we'll uh we won't predict every earthquake every day, but <v Al Lind>we will be closer to predicting the really big ones that cause damage. <v Al Lind>If at the same time we keep focused on the problem of building better buildings, better <v Al Lind>freeways, better bridges, at some point the 2 approaches will converge <v Al Lind>and we won't care if there's an earthquake. In fact, earthquakes will become like <v Al Lind>eclipses. They'll be great natural events you'll look forward to and they'll be almost

<v Al Lind>like celebrations [laughs]. <v Bill Kurtis>So you can get out of the way? <v Al Lind>No, no, no. People won't get out of the way. They'll come to see them. <v Bill Kurtis>And be here when we're arriving on that moving earth. <v Al Lind>Ask people who have really ridden out a big earthquake under circumstances <v Al Lind>where- you know where things weren't falling on top of them. <v Al Lind>Usually they remember it as 1 of the uh the uh really clear moments of their whole lives. <v Al Lind>And I had lots of people tell me they really enjoyed it. <v TV Announcer>Major funding for the new explorers is provided by Amoco, celebrating

<v TV Announcer>the adventure of scientific discovery for the year 2000 and beyond. <v TV Announcer>Additional funding is made possible by Waste Management Inc., providing recycling <v TV Announcer>and other waste services around the world and by Duracell <v TV Announcer>embracing the power of science education, the source of future technology and <v TV Announcer>innovative growth. Duracell, the copper top battery. <v TV Announcer 2>A videocassette and accompanying teacher's guide are available for each episode of The <v TV Announcer 2>New Explorers. To order call 1 800 6 2 1 0 6 6 0 or write <v TV Announcer 2>The New Explorers 1 5 1 8 1, Route 58 South, Oberlin, Ohio, <v TV Announcer 2>4 4 0 7 4.