 Okay we're back we're live we're protecting the Pacific today with the Pacific Tsunami Warning Center Gerard Fryer senior geophysicists there and we're going to learn today about tsunamis and tectonic plates and subductions and why it all happens and what happens to us when there's a tsunami. Welcome to the show Gerard. Thank you Jay. Great to have you here. You have to be here. So first I want to I want to paint that old picture you're standing on the beach you're swimming who knows what or you're in Waikiki you're right there in Waikiki in the most valuable beach in the world okay and you see something funny and maybe you should think this is a tsunami what do you see? Well that hypothetical situation would mean that we have failed at the warning center because we would know already and we would have a warning out. But the tsunami coming in a tsunami is a it's a long-term phenomenon people think it's just one big wave but it's not very often the first wave of a tsunami coming from a distant location such as Japan it may be fairly modest it may the water level may just rise a few feet and stay there for a couple of minutes and then drain away and you can see the beach and you can see yeah the water will drain away and you can you can see the sea bottom and there might be fish flopping around and then it'll come back and so you may get several waves like that in fact in 1946 both in 1946 and in 1960 the two big tsunamis in our recent history the first wave to kill anybody was wave number three in both cases in 1946 the waves were 15 minutes from one wave to the next in 1960 they were half an hour from one wave to the next so you know if ever the ocean does anything strange you should take heed and you know the ocean's strange yeah that's a warning yeah what no what do you do I remember uh what was that big one in southeast Asia not too long ago I mean in 2004 in the in there was a big earthquake off the coast of Sumatra yeah and it produced a tsunami across the Indian Ocean now tsunamis in the Indian Ocean are very rare there was no warning system in effect there and and so there was no warning issued and a quarter of a million people died in 17 different countries yeah wow so um they were at that the water's edge when this happened happened by surprise and those waves whatever the sequence was just inundated and drowned them how did they die um well the ones in the ones in indonesia the town of of Bandache a big city of of nearly a million people um there they felt the earthquake they you know very very severe shaking and um so so severe that you could um in video you see people sitting down on the ground because they can't stand and uh and then they got up and went back to their business they did not have a it was over yeah and now these are people who were a mile from the water but it's very very flat there and about 25 30 minutes later a big wave comes in and um um the way people die in a tsunami uh to start off on a more more big note mostly they drown but the reason they drown uh i've i've talked to um to some people doing autopsies and they they say it appears that mostly they drown because they have suffered some kind of trauma they have been hit by something debris by debris or something like that they've been knocked out or um so yeah i mean it's not nasty if you're in the water you're not alone you're in the water with with washing machines with pieces of coconut tree and building something will hit you and yes there's a lot in there and something will hit you yeah so um what now the tsunami comes and it races across this town this city um what's the next step the water recedes just as quick the water the water drains away uh maybe is quick or maybe a little slower but and it drags everything with it and uh and that and everything that's been dragged out that's just armament for the next wave so you know the first wave may not be carrying very much but the second wave is carrying all the stuff that was swept out from the first wave so and and so this can happen um and and in hawaii what tends to happen is the tsunami on the open ocean has has swept past us it's gone it's it's gone but the waves are still bouncing backwards and forwards between the islands and make and that can last for for hours for a frequency would you expect in this circumstance how how often would those waves come they're typically once every every five ten minutes once they start bouncing around certain certain bays um they will pick up uh a higher resonance uh one of our favorites is keiho bay on the big island that seems to oscillate at at about five minutes it's you have water level going up and down about once every five minutes so if you if you see one wave if you are experiencing or observe one wave coming in you can assume that's not the only way there's going to be other ways for sure that that's right and and the other important thing if we if we're down at the beach um in a in a region of hazard uh the other important thing to remember is that these waves are separated by a considerable distance no as i said 15 minutes typically from one wave to the next what that means is that that when the front of the wave the very edge of the wave is at your feet the crest of the wave is out over the horizon so so there's there's no way that you can just look at the ocean and figure out how high this water is going to get it's very very deceptive and i think that's a large part of the reason why people die this there's this phenomenon going on but the scale of it is so contrary to to a common understanding and huge this yeah yeah so when i look if i am standing unfortunately in wikiki beach seeing a wave in is is the is the crest of the wave going to be like a big surfing wave like one of those 25 foot surfing waves or is it going to be relatively small but a big under under bottom uh most of the time um it's just a big surge you know the water level just rises and the water just flows over the land like a river um in in some places and this happens in helo a lot you get so much water in on the land and then it then then it floods off and uh and then the next wave coming there's there's water flowing out as as the next wave is coming in and then sometimes the the the incoming wave then we'll we'll rear up into a vertical wall and so you'll have this vertical wall of white water coming at you um that's after that you can see the fish on the bottom yes open bottom yes that's pretty scary it's pretty scary but we have a warning system that that is pretty darn good and it gets better all the time so before we get to exactly how that works if there is a warning uh i don't know if this is siren or uh use you know public media like radio and tv both both everything everything we pump that word out yeah um what what do i do i mean if standing there watching or to get my surfboard for a quick uh surfing experience wouldn't be a good idea what do i do well um typically what's going to happen is this earthquake is somewhere on the nice thing about hawaii is that hawaii is isolated so we do have locally generated tsunamis but but they're um a fairly modest extent we can talk about them later if you like but by far the biggest danger for us is tsunamis coming from an earthquake across the ocean because they're bigger or because they're further um because that's where the big earthquakes are that's where the big tsunamis come from and hawaii is so so isolated that um the fastest tsunami from a from a big subduction earthquake the fastest it can get to us is four and a half hours and that would be for an earthquake in the allusions directly north of us so um so your first indication that something's up might be the siren going off you haven't felt anything then suddenly out of the blue the siren goes off what do you do what what we want you to do what all the emergency managers in the state wants you to do if the siren goes off you know we have the same sign for hurricanes for um for bomb threats they want you to find out what's going on so turn on the radio um and if it's a tsunami warning it'll say and uh and of course if you've if you've signed up for nixle uh you'll get a page on your phone um what's it called nixle nixle.com this is a service provided by the city and county honolulu free um you get all the emergency messages oh thank you for that nixle nixle.com right and it will also tell you about um about traffic jams and uh and flash floods and uh yeah it's sort of good good helpful might help you um so so that's what we want we want you to find out what's going on and uh and if it is a tsunami warning and if and if you are in the evacuation zone then you should leave and how do you know you're in the evacuation zone well what I would prefer is that you know you know that wherever you go wherever you work or live that you've looked in the phone book or you've looked online and you've found out whether or not you're in the evacuation zone but uh most people you know when the siren goes off that's when they look uh well okay we do have several hours but uh realize that everyone else is going through this same mental gymnastics and uh and so very quickly the roads are going to get jammed yeah I remember there was a tsunami warning oh I don't know us 10 15 years ago you you probably know exactly when but uh so you know we were in office building downtown and in that case we were in the eighth floor of the office building uh no actually it was the forget it was the 15th floor but um so at that time you could see everybody getting in his car and getting on alakaya street and winding up in one huge traffic jam going nowhere for hours yep that was probably 1986 uh 1986 was a very good lesson that was an earthquake we would not issue a warning for that that earthquake now um that that earthquake wasn't quite large enough to um well it's it generated a tsunami but it didn't really send it in our direction and we would know that now but it was a very good lesson because uh what happened was there was this earthquake and then there was a tsunami warning and uh and the state and the counties and many many businesses just let people off and so everyone just went home or tried to at the same moment all at the same moment and so while you were up you know looking down on alakaya at that same instant i at the time when the tsunami was actually meant to hit us uh i was on the summit of diamond head looking down into waikiki and every street in every direction was solid with cars it was absolute gridlock nobody could move yeah and so if there was a tsunami that in that case um the tsunami was like two inches tall or something it was really small it was actually it was uh it was about a foot actually foot yeah not going to do much that's right so uh if in that case if there was a real tsunami i mean a major tsunami from asia or the illusions would have you uh and you were stuck in traffic in your car you would be a really bad shape wouldn't you uh that's right i mean we don't ever want that situation to arise again um and how do you prevent it well uh here we're in a big tall building and there are big tall buildings in waikiki uh we don't even attempt now to evacuate waikiki just say move everybody move up how high do you have to move they want them to move up to the fourth floor or higher of a of a 10-story building we were on the 15th floor so i guess we were safe yeah and we we knew that i mean somebody told us that so um you know we felt we made the right decision even if they've been a real tsunami it would have been safe but you know one one question before we go to the break and that is uh you're relying on the structural integrity of this building as we know uh not every building has the kind of structural integrity you'd like to have and it could be the tsunami is going to push the building right down isn't that possible uh that is possible that's why we say a 10-story building because a 10-story building it's designed a 10-story building is a hefty building um and and if it's if it can handle the load just just the vertical load it's going to be built strong enough that it will also handle the tsunami um but if it's lower than that maybe not so much but um the only the only buildings i know of sure in in waikiki that that are real questionable the uh the original building of the moana hotel which is wood framed yeah um that that is not well it's not even 10 stories i don't know um but uh that that is one building that might suffer damage and then the original building of the uh of the royal hawaiian but most of the other hotels in waikiki they're actually they would actually perform pretty well and and when you think about it a hotel you know facing the water you've got these big plate glass windows and stuff you know because people get the view so the tsunami is going to come in and crash right through that but the bearing walls are on the side and and so they would cut the wave so yeah the wave is is um and and uh there actually is a study uh that the city is is is um promoting that it's trying to get funded um to uh to come up with um criteria for a building manager to check out his building and decide whether it truly is a safe site for refuge during the tsunami but current codes would be would be okay following the you don't have to change the code on this the building code uh there actually is a building code revision that will be coming up that will reflect tsunami loading for those buildings large enough to be deemed refuges you know what else is coming up to right our break oh thank you hello and aloha my name is raya salter and i am your host for power of hawaii where hawaii comes together to talk about a clean and renewable energy future i'm so excited to be here with you to talk about some of the most important energy issues of our day and most importantly who can we bring together energy engineers artists musicians accountants advocates young people who can we bring together to talk about how we can make this path together by walking and reach 100 renewable energy please join me tuesdays at 1 p.m for power up hawaii aloha i'm kawi lucas host of hawaii is my mainland every friday here on think tech hawaii i also have a blog of the same day at kawi lucas.com where you can see all of my past shows join me this friday and every friday at three p.m aloha we're back we're live we've had our break now we're back for more revitalized and we're going to talk about one other thing over the you know the physical properties of a tsunami and that is uh gerard fryer what happens to the ocean bottom is there a permanent effect you know we're worried about losing sand and losing beaches you know a tourist uh you know destination uh where we were worried about climate change in general and how it affects our our topography um what does a tsunami do to that uh that that might be permanent um well it's going to cause a lot of erosion it uh and and it's going to redistribute sediment um so so one of one of the fears uh if we have a big tsunami um you know will the channels in and out of hondledo harbour for example be clear will or in and out of pearl harbour that you might have sand that has been redeposited it couldn't happen very quickly uh yes if the tsunami pushes the sand say from the open beach or you know the initial beach it hits into say the alloy canal the alloy canal is going to be topped off well there's another thing that happens and that is you know a tsunami uh it's moving water all the way from the sea surface all the way down to the ocean bottom so it can actually mobilize stuff from some significant depth from from say a hundred feet or 150 feet down and it can mobilize sand from down there and transport it um but the other thing that happens is erosion and where it floods onto the land there can be erosion uh and actually it's nice that it picks up the sand because then it carries it in and leaves it um on the beach or on the plane that has been flooded save us the trouble well then we well we can come along a couple of thousand years later and and dig a dig a trench there and we see the sand and we say aha this came from the ocean you know this place is subject to tsunamis and in fact uh that is part part of the logic behind our new extreme evacuation maps that we have in Honolulu because we now know that that there have been these events in the past that were a lot bigger than we thought um so what about sea sea life you mentioned the fish you could see fish when the wave recedes how do those fish do do they get crushed and killed in the process well anything left on the beach obviously dies uh coral gets uprooted yeah um uh yeah I mean there's a there can be there can be major changes that out in the ocean things usually recover pretty well one of the big problems uh that tsunamis do um is that if it's really big and and you're a low island um your water supply may be contaminated because because if you know say you damage the lens if it's a coral atoll or something uh you know and you you uh you have a fresh water lens sitting on top and now that's being completely covered by salt water that's happening in the Maldives that's happened in the Maldives uh in in 2004 they basically lost their fresh water and that's that's a long-term loss that's a long-term loss uh they are recovering now slowly um but it was touch and go for a long time they had to have basically had to bring in water from outside if we were to build um climate change type uh uh infrastructure around our island such as Manhattan is doing um would would that help or hinder this effort in other words would would would that be able to stand up against the tsunami probably not uh and would would it exacerbate the result of the tsunami in some way well um that experiment has been tried uh japan uh pours a huge amount of concrete um and they there are many areas in japan where they have where they have these tsunami walls um in most cases they they've made the wall as big as they think the largest tsunami is going to be unfortunately what happened in 2011 was they they underestimated they they didn't nobody thought nobody thought including me uh nobody thought at that time that japan could ever have an earthquake larger than magnitude 8.4 and that that earthquake was actually magnitude nine and the way the tsunami was way way bigger than anything they expected it's a logarithmic scale isn't it uh nine is way bigger than eight that's right yeah nine is actually 32 times bigger than an eight okay putting in a perspective yeah um and and in fact uh we now realize that what they what they had done they they had basically prepared themselves for the hundred year event for the worst event likely to hit them in a hundred years but then they got hit by the thousand year event and uh and the consequences for them of getting that wrong was so severe that you know that the rest of us have to take notice and and so we at that point we go back and look at how hawaii had prepared itself and we realized that we had done exactly the same thing we basically had a hundred year perspective and we ought to have a thousand year perspective and so that's why we now have these new extreme zones on the maps so we now have two zones we have the normal evacuation zone and then if it's truly the big one you evacuate the yellow the yellow area as well so all this is under the auspices of what noah or the city and county or a combination of agencies uh well the warning system is is noah it's actually part of the weather service uh so that's federal um the um that's that's the the science side of things initially initiating the warnings the sirens belong to the counties the evacuation maps the determinations about those are made by the counties um the state uh acts as a as a thoroughfare for federal money uh and uh and distributes it to the counties uh through primarily through the national tsunami hazard mitigation program um but uh we all talk to each other a lot we we all sit down at the same table we all know each other um and and this state actually works really well fed state counties they all get together very well yeah we're really exposed to Idaho doesn't have to worry about this uh that's right yeah yeah you can quote me on that you heard it here on think tech speaking of technology i'd like to talk about you know the most recent events in the tsunami warning system because you know we kind of woke up when we went to the thousand-year way of looking at it right um and we realized as we should that tsunamis are part of earthquakes earthquakes in this in this globe in this planet are always going to happen right and therefore tsunamis are always going to happen um and we just have to live with that so the question is uh how good is our warning system and last time i looked we had we had only these sensors uh out in the oceans uh you said there were seven thousand of we have various sensors uh there are like 700 seismometers so those we use for measuring ground shaking and that's where the initial warning comes from and then we have about 50 tsunami sensors these are these are deep ocean pressure sensors as the tsunami goes across as they measure a slight increase these aren't buoys hanging off buoys or it's actually it's a device sitting on the ocean bottom and then there's a surface buoy and the device on the bottom two talks to the surface buoy acoustically it actually issues a little a ping a chirp uh and the signal is encoded on that and um and and so those measure tsunamis as the tsunamis come across so if the water rises very quickly that buoy is going to know that that device on the bottom is going to know it will know and and and uh and they can measure uh they can measure waves uh you know a quarter of an inch yeah you can measure um and and those are really nice uh the trouble is that um before you know about a tsunami from those things the tsunami has to have got there from where it started and typically that takes about you know 40 minutes or an hour or something like that um so all of our warnings are initially based purely on what we could what we learn about the earthquake because and that's because the shaking from an earthquake travels very fast through the earth so so we know about an earthquake and we can issue a warning within 10 minutes because every earthquake results in a tsunami no no what's what kind of earthquake results in a tsunami and what kind of uh you know seismic event results in the worst kind of tsunami okay um to make a tsunami you basically have to change the shape of the ocean bottom and and um and i the ideal way to do it is to raise or lower the bottom so uh if uh you consider the san andreas you know where which is what we call a transform fault where once the where the pacific is moving in one direction relative to north america all the motion there is horizontal so so if that fault were under underwater and if there was a large earthquake all the motion is horizontal you're not late raising or lowering the water so there's no so there's no tsunami so that movie san andreas you know that's that tsunami no sorry that that that wasn't right you heard that here on think tank also um what happens uh say in the pacific northwest and and along the allusions and in mariana islands there you have a tectonic plate that's diving down underneath the edge of the continent um and so the whole edge of the continent or or the island or the island arc is is caught against this thing that's coming down and it's deformed more and more and more and then it can't take it any more and eventually it breaks uh like snap snap yeah and when the snap actually lasts for about three or four minutes that's the earthquake so so what you're doing is you're raising the seafloor over an area that might be like 70 miles wide and maybe 200 or 300 miles long and you're doing it in only three minutes so what you've done is you've changed the shape of the ocean bottom faster than the water can get out of the way but you basically lifted the water is not compressible right it's that's that's right yeah we assume that water is incompressible it actually is a little huge yeah okay um but if it's it's uncompressible it has to go somewhere that's right yeah something's got to give and um and so you raise the ocean surface and and gravity doesn't like that and this lump collapses and and it oscillates and and that's where the waves of the tsunami come from now the technology has changed uh or at least been enhanced by gps can you talk about that uh yeah um with with seismometers you're basically measuring waves and and uh we're interested in measure we we in particular want to be able to measure quickly the size of the largest earthquakes the trouble is that when an earthquake gets really big uh the uh the waves that it generates are determined by the size of the area that was ruptured so that may be very very low frequency like like five minutes from one wave crest to the next and you're measuring that with a seismometer that takes time and um you know you're measuring you're measuring wave amplitudes on a wave that has a period that lasts for five minutes uh so so it you know you basically have to take five minutes to make the measurement and uh you know we want those five minutes um gps is different gps uh the geodetic grade gps which which measure which can measure motions down at the millimeter level um there um it can see the the motion immediately can see it can measure displacement immediately so um um you have a lot of data to work from now you have much more data than you did simply with the sensors as a result right do much more profound calculations on this yeah that's that's yeah and you have it you you get the measurement a lot faster the only gotcha is that you've got to have the sensors very close to where the earthquake is going to be may not always be the case well that is the case in japan it's the case in the pacific northwest it's the case in south america which are risk areas yes all of those areas now have enough we're getting a lot smarter aren't we oh we get yes yes and the and the other wonderful thing is that everybody shares data all of it yeah everybody we realize that we're all in it together yes and and uh we are in it together and we really appreciate you sharing the data gerard fryer senior geophysicist in the pacific tsunami warning center we've only begun in the technology you'll have to come back because i want to may i say drill down on that absolutely sure yeah thank you gerard thank you so much