Remembering the American Samoa Tsunami – September 29, 2009


-warning sounds- -warning chimes- Man! This is a big one. Let me call PTWC. On that morning, I was inside the classroom preparing for my class and then it started shaking. I felt this vibrating or shaking so when it went strong I asked my Mom and my sister to run out the house with me. It started to shake stronger. That is the warning to you to start run to the high place. And then right before it stopped and I started asking our teachers to, to have the students form up a line and started walking. -phone ringing- This is the National Weather Service. Yeah, PTWC, this is Pago Pago. This is Akapo. We just have had a very strong earthquake here. It went on, the duration probably about two, two minutes. This weird feeling I have looking at the ocean, it’s all bubbling. So, I told her that it’s going to be, there’s a tsunami coming afterward. And then she asked me what would it be best to do. So I said I’m going to ring the bell. We had an amount of hundred plus kids reporting to school that morning. Ringing the bell, I could see them come running. It took us less than ten minutes to cross, going up to the hill. 8.0. We got an 8.0? Yeah, 8.0. Time is 6:48am. Where’s it at? Distance of 120 miles south of Apia. 120 miles south of Samoa, of Pago Pago? So that means it will be what, will be here in less than fifteen minutes? Yes. Oh. Well, I think we better issue a verbal warning. We won’t have time to wait for PTWC. OK, I’m going to call Homeland Security right now. In the meantime . . . Narrator: The National Weather Service office alerted the Department of Homeland Security to issue an oral warning and to activate the Emergency Alert System. NOAA has now issued a tsunami warning for American Samoa, effective immediately. It’s a wave! Akapo got a hold of him and he said, “This is me – Akapo”. And I said, “Akapo, we need you. What’s going on? We need a sure word of what’s going on.” And he said, “Put me on air.” In five minutes or seven minutes, right after the earthquake, and Akapo, we connected with Akapo. and so Akapo spoke, and gave the warning. I saw the waters splash over the sewing shop in front of the ocean. So I shouted that the water is coming. So I shouted to go up higher and the only building I know was our second floor here. The second splash, I saw everything when all the buildings topple down. And everything there was came to this school. People started saying there was a wave. There’s been a wave. We heard sound of the, of the houses that had been demolished by the, by the wave. Those voices of the kids screaming, yelling, they’re panicking, they’re worried about their parents. “Lord Jesus Christ please give us the power to accept the things that are going on here. We understand that this is the power of nature.” My host Dad went down and they said, “Everything’s gone.” Everything was destroyed. Then I got to the school and my classroom was just a pile of rubble, and none of it was mine. I found the cover of a book, and a thing of stickers, was all I found from my classroom. The earthquake of September 29th was so close to American Samoa that the tsunami waves arrived less than 12 minutes after the earthquake started. Many coastal villages were struck by the tsunami as it hit on all sides of the island, and waves continued to arrive for up to 90 minutes. The images of the destruction and damage from the tsunami reveal the powerful force of nature. It is a day that must be remembered for all that was lost. -music- Scientists have studied the events of that day. Their research helps us understand how this happened. My name is Steven Ward. I’m a research geophysicist here at the University of California, Santa Cruz. My main interest is seismology, but I also do natural hazards, like landslides, tsunamis, asteroid impacts. Most tsunamis around the Pacific Rim are caused by something called subduction zone earthquakes. In those places, the crust of the earth is being pulled into the center of the earth. So it slowly gets pulled down, and it adds energy to the upper plate and it springs back and makes a tsunami. When I hear of an earthquake along the Pacific Rim, that’s the mechanism I typically think of. My Name is Thorne Lay. I’m a Seiemologist and a Professor of Earth and Planetary Sciences at the University of California, Santa Cruz. Well, initially the earthquake on September 29th interested us because it was clearly a magnitude 8 earthquake that was quickly determined by the U.S. Geological Survey. And we knew that such a large earthquake can produce a tsunami. For the September, 2009, Samoa earthquake, I did like I usually do. I put in the information that the seismologists can give me about the size of the earthquake, the location, the type of faulting. I put that in the simulation and developed an estimate for the run-up in American Samoa and it came to about two meters, two and a half meters. We quickly confirmed that the primary faulting had been a rupture within the Pacific Plate, just to the southwest of American Samoa. And it was an unusual earthquake in that regard. And it probably displaced the ocean bottom by on the order of ten meters. Almost within hours you get some initial reports of the wave damage and clearly I was way low. You get reports of four meters, five meters, six meters, eight meters, reports of damage and casualties. So clearly, I know right away that something that went into the simulation was not right. The most unusual aspect is that it triggered a second earthquake, what we could call a stealth earthquake, about forty seconds after the first event so it was hard to detect it because the strong vibrations from the first event concealed it. And that was also a magnitude 8 earthquake. And it turns out that the refinements that have been done recently help explain why the initial tsunami models were so low. This extra earthquake, this outer rise earthquake, was much more powerful than we would have imagined. It had a mechanism such that it was very efficient at generating tsunamis. The slip in the earthquake was very compressed to near the surface. And all of those circumstances combined, made for a wave two to three times bigger than first guesses suggested. So we have both a breaking within the plate and then we have a pair of magnitude 8 earthquakes only about 70 kilometers apart occurring within two minutes. The outer rise earthquake, the tsunamigenic part of it, was in fact beamed right at Samoa. That’s the reason so much wave energy happened there and not elsewhere. The wave approached American Samoa from the southwest. It hit the western side, made some pretty big run-ups there, but it also tended to wrap around to the north and to the south because of the shallowing water. Waves always bend towards the direction of shallowing water. So this part of the wave might have missed Samoa, but the shallower water north of it tended to bend the wave in and it came smack to the north and to the south. For people in American Samoa, the primary hazard that they’re going to be exposed to is most likely tsunami coming in. There’s two types of tsunami warnings. One is called the official warning, where you wait for someone on the radio to tell you what to do or not to do. That’s fine, but it takes a couple hours for the whole system to work, to get information to the center, to decide what to do, to radio that, to telephone the emergency services people. If it’s a local earthquake, there’s a chance that you can save yourself by quickly reacting as soon as you feel the ground shake. Because the waves go through the ground, the vibrations of the ground, at a faster velocity than the speed of the wave in the water. So if you feel the ground shake, immediately evacuate from low lying regions, get to high elevation, or if you’re in a strong building, go upstairs, do a vertical evacuation, because you may only have a few minutes before a tsunami comes in, but you’ll have been alerted about that potential by the shaking of the ground. Big damaging tsunamis are pretty rare, maybe once a decade somewhere in the Pacific. It’s a good chance that the people of Samoa won’t experience a big damaging tsunami again in this generation. But that doesn’t mean they should forget about it or learn the lessons that they have learned. People say that if you forget about history you’re going to relive it. That’s certainly true with tsunamis. Several ways to keep that memory going is to learn about it now – interesting stories, maybe do some research of your own. You can also pass the stories down to your children. They may not ever see a tsunami, but you can say, “You know, when I was your age I saw a wave come up to this part of the beach and knock off so many houses.” And they’ll be, they’ll remember that type of thing and what to do under certain circumstances. You’ll be surprised what a little story will, will carry it with your children. -music- Narrator: It’s important that tsunami survival be taught from generation to generation. These lessons include: there is frequently not enough time for official warning; if you feel a strong earthquake, that IS your warning; or if you see the ocean recede, bubble or act strangely, take immediate action to save yourself, DO NOT wait to be told what to do; evacuate to high ground as quickly as you can, you may have only minutes to act. Remember, a tsunami is a series of waves, sometimes hours apart, so stay on high ground until you receive an official “All Clear” message from government sources. While the events of September 29th, 2009, will be remembered for a long time, it is also important to not live in fear of the ocean. These are the same waters that have provided for generations of Samoans. It is where your children and their children will play and grow up and fish. But we must educate them about what may happen in their lifetime or their children’s lifetime. And they must pass this information on. By doing so, we can help save the lives of Samoans yet to be born. -music fades out-

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