 Coming up on this edition of OAS News in Depth. Unfortunately, a major tsunami is possible in California. Scientists acknowledge the threat of large tsunamis along our coast. But are they talking about those the size of the one that devastated Japan in 2011? And would you know what to do if you heard that sound? It's Tsunami Preparedness Week in California and we'll have some potentially life-saving info for you. I'm Brad Alexander and we have that next on this edition of OAS News in Depth. Hi, I'm Brad Alexander in the Cal OAS State Operations Center. March 27th, 53 years ago, a 9.2 magnitude earthquake struck off the coast of Alaska, triggering tsunamis up to 220 feet high, killed 139 people. This week, the week of March 27th is also Tsunami Preparedness Week. Here are a few questions for you to think about. Who are really affected by tsunamis, just people who live along the coast? What is a tsunami? And lastly, what's the best way to evacuate if one is on the way? We'll tackle those questions in a couple minutes. But first, that great Alaskan earthquake is still the largest to hit North America, the second largest to be recorded in the world. And there is a lot that scientists still don't know about how earthquakes influence tsunamis. OAS News' Sean Boyd traveled to the coast to talk to one expert who rolled the dice on a big experiment. To learn more. Well, this year's Tsunami Preparedness Week runs March 27th through the 31st. And here in Santa Cruz, there are plenty of signs like these that let everyone know that this is a tsunami hazard zone. But just up the roadways at UCSC, there is at least one scientist who is going to extremes to understand the connection between plate tectonics and tsunamis. March 2011, a massive 9.0 magnitude earthquake rocked the ocean floor off the east coast of Japan. The Tohoku earthquake created a tsunami more than 130 feet high in some places, one that destroyed coastal towns, caused nuclear accidents and killed nearly 16,000 people. 14 hours later, that tsunami reached the coast of California. Santa Cruz bore the brunt of it. Scientists now know that during the earthquake, the sea floor moved more than 150 feet in just a matter of minutes. He had no idea that the sea floor there could move by that enormous amount. Emily Brodsky is an Earth and Planetary Sciences professor at the University of California, Santa Cruz. She says the enormous size of that quake and the resulting tsunami planted the seed for an ambitious scientific expedition. We thought we should go and look at the fault that made that earthquake and figure out if there was anything special about that fault. So she and scientists from 12 countries began planning an expedition to the Japan Trench Fault. They called it the JFast Drilling Project. They would use the world's most technologically advanced drilling vessel, the Chikyu, ported in Japan. The crew set sail on April 1st, 13 months after the quake. Their goal? Probe more than four and a quarter miles below the surface of the ocean. Drill another 2700 feet into the seabed, take course samples and take the fault's temperature. Why'd you do that? That's a weird thing to do. Professor Brodsky says that was a key motivation for the project. Measuring the heat on the fault tells a lot about the friction on the fault. More heat means more friction. It's that friction or resistance to the Earth's plates movements that can impact the buildup of energy in those plates. Here she breaks down what plate tectonics are and how tsunamis are formed. Usually the fault is not moving and every once in a while the fault suddenly jerks forward. When that happens it pushes up the top here, the top of the blocks, which is the bottom of the ocean. And by pushing up the bottom of the ocean it pushes up a big column of water and that makes a giant wave that is the tsunami. Once at the fault, crews aboard the Chikyu successfully drilled not one, but multiple holes into the fault. Remember, that's more than five miles below the ocean surface. This is the first time this has ever been done. Into the holes they plunged 55 data recording thermometers to measure temperatures inside the fault and they left them there for nine months. When they retrieved the sensors and analyzed the temperature data, the results confirmed their suspicions. And what we found was this thermometers that were sitting right on the fault were just a little bit harder than the ones that were far away from the fault. They were a third of a degree harder. That was really exciting to us because what it meant was that extra little bit of heat on the fault is the sign, the signature of friction. Friction that allows energy to build up and eventually release with potentially catastrophic results. When a really large earthquake happens it can release all of the stress in the system. And so after that really big event it's going to take a really long time to accumulate stress to make another earthquake. Another quake that big in the same spot will likely take centuries to happen again. It'll simply take that long to rebuild the energy. This is something Professor Brodsky says scientists have debated for years. This is a big step in fully understanding the science of tsunamis. Unfortunately a major tsunami is possible in California. I live not that far over the water there and my daughter goes to school right next to that cliff over there. And so I want to make sure that my daughter's school has a good tsunami evacuation plan. Because it is in the inundation zone and it really could happen here. In Santa Cruz, Sean Boyd, OES News. Thanks Sean. So as promised back to the questions we posed at the beginning of the show, Kelly Houston sat down with Ryan Arba. He's our tsunami program manager for Cal OES. And for the answers here's Kelly. We're joined by Ryan Arba. He's the program manager for the tsunami program at Cal OES. Ryan thanks for joining us. Great to be here Kelly. Hey so there were some questions at the beginning of the show that we kind of left open. Didn't tell people what it was because they're misnomers. One of them is about who's really affected by tsunamis. In other words, if I'm a person who lives up in the mountains, I don't really go to the coast. I kind of look at this and say isn't this really just applicable to people who live along the coastline? Like why do I as a person who lives in Sonora or just in the Sierras need to worry about it? Well earthquakes can happen at any time. And the same thing applies to tsunamis, they can happen at any time. So it could be that you are, say you live in the mountains but you're down in town near a river through the delta. That could be impacted by a tsunami. You could be on your annual Christmas shopping trip to San Francisco. San Francisco can be impacted by a tsunami. You or maybe you have friends and family visiting from another state and they decide to go to the coast for the day. They can be impacted by a tsunami. So though the tsunami does affect the coastline, we want to get the message out to everyone to make sure that they're prepared should this event occur. So the point is the waves not going to hit up in Sonora or up at the high mountain levels but you could be in the same area where you don't really kind of think of that. That's actually a really good point. The other one is that there's this idea that a tsunami hits, it's a big wave comes in and washes over everything and then it kind of recedes. And so I've heard some people say, hey, if you can get through that wave and it hits, you're good to go. Go back out swimming, take your surfboard out, you're good. Is that true? No, that's one of those myths that we like to dispel with our program. That first wave often is not the biggest wave. It is often not the wave with the most impact. In a tsunami, waves can occur over several hours and you don't know exactly which one is going to inflict the most damage. So it's something that we encourage when the tsunami warning comes, take the proper actions as instructed by your local community members and local officials. And make sure you stay away until you've received word that it's safe to come back. So it's sort of like a tsunami is not just a single thing. It's a series of waves that come across and the first one may not even be the biggest one. I know that's something that a lot of people have been like, wow, I didn't really think of that interesting. So it could be lasting over a course of many hours. The last one is, so I'm in a tsunami zone where I could be affected by a tsunami. Let's say I'm along the coast or whatever and I hear the warning or I know that something's going wrong. So I want to get as far away from that as possible. So if I get in my car and I just keep driving, the further I drive, the safer I am, right? Well, it's not necessarily always true. If you think about it along the coastline, if you were to say drive further north or south, but stay along the coastline, that community that you're traveling to could be going through the same thing and still have a similar risk that could be present where you are coming from. So what we do is we encourage every person in California when they visit the beach or if you're a member of that community, take a look around. We've invested heavily in creating tsunami signs to identify when you're entering and leaving a tsunami hazard zone. And then in the event where you may have to take actions as a result of a tsunami coming, we've used those signs to show you what those proper evacuation routes are. And I think that's a good point too because I know myself. You go into an area along the coast, you see a tsunami sign and I'm like, oh, they're just reminding us that a tsunami could occur, but they're really directional. Absolutely. If you follow that, it takes you to higher ground. So you may not even need to get in your car. You could just walk a couple of blocks and be at a safe location and have not been kind of caught up in a big traffic jam trying to get out of town. In fact, we encourage you to think if you've ever left a stadium after a game and just how log jam they can get when a few hundred cars try to leave after that point. Same thing could happen in a tsunami event. So it's something where if you're able, walking or taking other means of transportation other than your car could be the best path forward for you. Great tips. And I know we have a website for more information. So Ryan Arba with the tsunami program, thank you very much for joining us. Thanks Kelly. Thanks Kelly. And we have more from our university experts and from Ryan Arba as well as another professor from UC Santa Cruz on our website at OESNews.com. Click on the links to watch those and be sure to subscribe to get all the best updates from OES News. And for the entire team here at the headquarters, I'm Brad Alexander. Thanks for watching this edition of OES News in depth and we'll see you on the next one. Go to tsunamizone.org to learn more. Find out if your home, school or workplace are in a tsunami hazard or evacuation zone. Understand the difference between a tsunami watch, advisory or warning and what you should do before, during and after a tsunami strikes. You can also make your children's tsunami superheroes by downloading a free e-book with interactive games. Go to OESNews.com slash tsunami where you can watch extended interviews with experts on the front lines of research and safety and find dozens of other videos on a wide range of topics that matter to you. Connect to the Cal OES community on Facebook and Twitter or at OESNews.com.