Tsunami Research Keeping People Safe
When a 40-foot tsunami wave hit the shores of American Samoa on Sept. 29, 2009, thousands of locals made it safely to higher ground, thanks to education efforts and research.
Listen to an interview with USGS oceanographer and tsunami researcher Bruce Jaffe as he explains why this post-tsunami research is essential for keeping people safe in future tsunamis.
Kara Capelli: Welcome to USGS CoreCast. I’m your host, Kara Capelli. In the weeks after the deadly tsunami in American Samoa, a rapid response team of USGS scientists traveled to American Samoa to collect data, data that will soon be gone as recovery activity and natural events overtake the area. I’m joined today by USGS oceanographer Bruce Jaffe, who was part of that rapid response team. Bruce, thank you for being here.
Bruce Jaffe: Thanks for having me.
Kara Capelli: Bruce, how big was the tsunami that hit American Samoa?
Bruce Jaffe: It was hit pretty hard. I was actually surprised by how hard it was hit. The reports I saw in the newspaper were 15 to 20 feet which is a plenty big tsunami. But what I saw there was that it was up to 40 feet high. The elevation was up to 40 feet high and there were places on the northwest coast where the depth of the tsunami was upwards of 20 feet.
Kara Capelli: So why was it so important to collect data right after the tsunami hit?
Bruce Jaffe: The data we’re collecting, that's imperative to be collected as quickly as possible after the relief efforts, the medical relief efforts, the humanitarian relief efforts start winding down is water levels. That information actually was gone in a lot of places. Even six days afterwards people had scrubbed the outside of buildings, etc. And what's important about the water levels is that the models for tsunamis inundating the land are good but they still need to be improved. And by improving those models, we can better assess tsunami hazards for tsunamis in the future.
Kara Capelli: And what kind of information can a tsunami model tell you?
Bruce Jaffe: Well the most important information they can give is how deep the water is and how fast it is moving. It is surprising how little a tsunami can be deadly. A tsunami that's basically between your knees and your waist will knock you down. It's very fast-moving.
So these models, by predicting what areas are going to be hit, by different sized tsunamis, you know, what the danger zones are, can help with evacuation routes, building stronger structures, and putting your structures in places that aren't going to be in areas where the tsunamis are larger and faster.
Kara Capelli: So how will this information help prepare cities and villages for other tsunamis?
Bruce Jaffe: Well the information we collected is very valuable for mapping what areas are hit hardest from this tsunami. If this tsunamis is a rare event, if say it happens every 500 to 1000 years, it's likely that people live with the risk of keeping homes and critical facilities near the coast. But if this is a more frequent event, choices might be made to redevelop differently.
Kara Capelli: Bruce, do you have anything you would like to add about how information and education can keep people safe during a tsunami event such as this one?
Bruce Jaffe: One thing that brought a smile to my face and still does about this tsunami, although it's extremely large, the peoples of American Samoa and Western Samoa did the right thing. They felt the earthquake and they knew that a tsunami was coming because they have been educated. There have been a series of courses in schools, community leaders have been educated. There had been evacuation drills. People knew what to do in a tsunami and they needed to do it quickly. They needed to go to a higher ground within 15 minutes or less. And they also needed to know that a tsunami isn’t just one wave. A tsunami is a series of waves. There are between 3 and 5 large waves, and these, you know, took hours to come and go. You want to stay a way from the coast for a long period of time. So, although the death of 32 is high, it could have been easily in the thousands if people hadn't known that as soon as they felt the earthquake to get to a higher ground.
Kara Capelli: Bruce, thank you so much for being here today.
Bruce Jaffe: Thank you for asking and I think the message needs to get out on how we are going learn a lot from this and even more so that the people of Samoa did the right thing, otherwise, there would have been many many more deaths.
Kara Capelli: Thanks Bruce. And thank you for tuning to this episode of CoreCast. You can find more information and updated notes from the field about this research online at http://walrus.wr.usgs.gov/news/samoareports.html.
CoreCast is a product of the U.S. Geological Survey Department of the Interior. Thanks for listening.