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Remembering Japan's 2011 Earthquake, Tsunami

Remembering Japan's 2011 Earthquake, Tsunami
Remembering Japan's 2011 Earthquake, Tsunami GUESTS: Pat Abbot, geology professor emeritus, San Diego State University Dave Sandwell, geophysicist, Scripps Institution of Oceanography Ken Buesseler, senior scientist, Woods Hole Oceanographic Institution

The numbers are devastating the magnitude 9.0 that struck Japan five years ago this week shook the buildings and countryside for almost 6 minutes. Japan last five years ago was on an active trend in its adaptive soon that a slab of Pacific ocean was being pulled underneath Alaska, Russia and Japan. When you got word of this earthquake did you think the West Coast may feel the effects of the tsunami? Most definitely. Interestingly enough if late trading sides of the ocean. We basically had 89.0 magnitude earthquake off of Oregon and Washington in the year 1700. Now the Japanese had the best tsunami record in any society and they recorded a very large killer tsunami from that event in January of the year 1700 so this is almost reciprocal. Now it's their turn to have 9.0 earthquake and I meant the tsunami met this number should come across as well. It's going to Japan first. The cars will get hit the highest. The flute transmits the energy well. The tsunami not only travels across the ocean to North America and it's not can be as high in North America as in Japan but it bounces back and forth across the Pacific ocean several times. It's a tremendous amount of energy put in the water it takes quite a while to dissipate. Since 2011 a lot of study has gone into the details of the Japan earthquake. Dave Sandwell is a geophysicist and the co-author. Thank you for having me on the show. This earthquake caused an unusual slip. As Pat described this is on a subduction zone when you have one plate going under the other and normally when you have a made a thruster like this you have about 10 to go 20 m of slip which is about 60 feet. This earthquake slipped 50 m which is about 150 feet in the area of the slip is about equal about the size of San Diego County. It's a large area. It's an unusual large slip but not so big of an area. Apparently it happened I'm sure on a shallow depth and that is significant for a tsunami is that right? That is correct. When you have these mega thrusters sometimes they produce a tsunami and sometimes they do not. It all depends on whether the rupture or the fault goes all the way to the seafloor and to the surface to the bottom of the ocean and if it does you get a lot of uplift may be 10 or 30 feet of uplift would generate the tsunami and that's what devastated the Japan coastline. This study that scripts did under the tote looking under the geological formations under the ocean is that so much study that has gone into the sea study of the floor in an area of an earthquake? I would say it's the first time but a different result. We are trying to relate the long-term shape of the seafloor to present-day locking on the fault. What I mean is if you have these plates sliding under the Japan over thrusting late and if it locks during the [ Indiscernible ] and that's between the big earthquakes than you will have a big earthquake back and slip a lot. Sometimes the fault slip freely and creep and when they creep you will not have a big earthquake. We will looking at the structure of the seafloor and relating that to the amount of locking that occurs the different parts of the fault. I've been speaking with geophysicist Dave Sandwell. Dave, thank you for your time. Thank you to be on your show. Pat Abbot is still with us. I ask you to explain if there is a potential for one for the US coast. Would like to use this metaphorically like the hard-boiled egg. If you look at the earth like a hard-boiled eggs it has a brittle shell and that outer brittle shell is on the order of 60 miles thick. Just like when you break the shell of the hard-boiled egg you can move the pieces around so the pieces of earth they move in places where they collide like in Japan and are pulled down underneath the continent that's where you get your biggest earthquakes. For the 50 United States, three of them have had and will have more 9.0 magnitude earthquakes and that Alaska, Washington and Oregon. Alaska had it in 1964, Washington and Oregon in 1700. The second disaster caused by the Japan earthquake was a radiation leak at the Fukushima nuclear plant and surprisingly there's no US agency responsible for tracking radioactive contaminants in the ocean. Fortunately team of scientists have been tracking the Fukushima radiation and joining us now is Ken Buesseler and is radio chemist at the Woods Hole oceanographic institution in Massachusetts. Welcome to the program. It's my pleasure. After the disaster you assembled the team to detect radiation levels. Now five years later is the Fukushima site still leaking? Recently as last October we reported even early on despite the fact that the levels decreased a lot within a couple of months they would down 1000 times but they had been so high that these levels are still of concern and as we go back over time they decrease but not going back to what they work before. You're not only treating radiation levels in Japan but also along the north American coast. Tell us about that. What are the radiation coast along California's coast today? What happened a few years ago or so focused on Japan we weren't as active on the West Coast and realize there was no mentions being made by the federal agencies but the public Demanding what's going on. We did a crowdfunding effort and got now up to 250 samples and for Hunter individuals involved in collecting these analyses. What we're seeing as we expect for much smaller levels that are near Japan and not in the millions or thousands but a few of these units that we seized in the ocean is the amount of radioactivity and a certain amount of water. We are talking that we did analyses of the West Coast every day if you're go swimming for an entire year even with this slight increase that total dose the amount of exposure is 1000 times less than a single dent that you choose to take. It's not zero but one or two of these units is pretty small compared to tens of millions at that peak of Japan. Is a reason to expect his levels will did -- decrease over time? They're starting to show up a year ago this time in British Columbia and we are starting to see some elevated levels offshore. I don't think we have reached the peak yet. We are talking about thousands of times last than what we saw in Japan. I'm not as concerned about health and safety issues but it's certainly worth monitoring and having that information to tell people whether it is high or low Is not dangerous you say? At these low levels near Japan at the peak they would have been direct harm to Marine life at those high levels. I've been speaking with Ken Buesseler from the Woods Hole oceanographic institution. Tapley go back to you. Do you think we have acted on the lessons we've learned from Fukushima especially considering there's radioactive waste that will apparently be housed for many years to come. This is one of the great problems for the nuclear energy. It's not a good enough appreciation that even after that radioactive material has lost enough of its energy that is no longer useful to generate power it takes thousands and thousands of years for that material to cool down to the word is not a threat. As a geologist if you ask me or you ask us where in the world is a safe place where we can put radioactive isotopes away from society and not have them be harmed the short answer is there is a very active place. There's no place on earth that you can guarantee that will be stable enough to store these things safely. Therefore that's why we end up with these things like this. There is no safe place so basically these are kept on-site on -- in places around the world. When it comes to lessons learned from Fukushima do you know that indeed with all this monitoring and everything we have learned significant lower -- lessons from this earthquake? We always learn some things but have we learned enough to make everything safe? No but we do get better prepared all the time and I like the upward learning and the upward improvement curve but mother nature can throw at us and there may be no safe place to store the radioactive waste. We will be seen these kinds of problems again in the future. Pat Abbot geology professor at emeritus. Thank you for speaking with us. Thank you. Coming up we get to hear from a San Diego super voter. It's 12:24 and you are listening to KPBS midday edition.

On March 11, 2011, a 9.0-magnitude earthquake struck off the coast of Japan, triggering a tsunami and leading to a nuclear meltdown.

Five years later, the Fukushima Nuclear Plant is still leaking.


The scientific community has come together to learn more about the disaster, from pinpointing what may have produced the mega-earthquake to tracing radiation levels in the Pacific Ocean.

“Japan five years ago was on the most active trench in the world,” Pat Abbott, a geology professor emeritus at San Diego State University, told KPBS Midday Edition on Wednesday.

“A subduction zone where the Pacific plate, about a 60-mile thick slab of Pacific ocean floor is being pulled underneath Alaska, Russia and Japan,” Abbott said.

He worried that the same earthquake that caused the tsunami at Fukushima would bring a damaging ocean wave to San Diego. That could have threatened the then-operating San Onofre Nuclear Power Station near San Clemente.

“When you have these mega-thrust earthquakes, sometimes the produce a tsunami and sometimes they don’t,” said Dave Sandwell, a geophysicist at the Scripps Institution of Oceanography in La Jolla.


Sandwell said researchers are trying to understand what happens to the ocean floor when these large events happen. That will allow them to better understand how tsunamis form.

Scientists are also concerned about the effect of radiation from the meltdown at the three Japanese nuclear reactors.

“Despite the fact that levels (of radiation) decreased a lot in the few months after the accident, they had been so high that these levels were still of concern,” said Ken Buesseler, senior scientist at the Woods Hole Oceanographic Institution in Massachusetts.

Radiation levels are not going back to the levels they were before the accident, Buesseler said.