Tsunami In Our Future

let's start with a map of the Pacific Northwest one of my patented maps Washington Oregon and California will put Ellensburg right in here okay great I mentioned last week that it's important to teach science as a work in progress and I try to do that whenever I can and tonight's lecture is maybe one of the best examples of how quickly science can advance our understanding of a particular topic I'm gonna use tonight tsunami research as a way to demonstrate that let's go back to 1985 shall we 1985 I was a graduate student and I was taught in an earthquake geology class of North America that the Pacific Northwest did not experience great earthquakes this is 1985 I was taught I wrote it down memorized it for the test answered the question correctly NOAA big earthquakes in Washington and Oregon that was the current scientific understanding in 1985 that somehow the Juan de Fuca plate was subducting beneath North America a seismically or without major earthquake activity and if what I just said doesn't make sense to you again let's do some real basic stuff here this involves plate tectonics and if many of you I know are old enough to have taken a college coursework in the 40s or 50s or 60s and you weren't hearing about these plates right well that's now a real basic part of what geology is so here's a very simple picture for what washington has experienced plate tectonic Lee here's Washington on the North American plate coming east excuse me coming West and here's the Juan de Fuca plate coming East in subducting beneath this plate interaction has been responsible for creating volcanic activity to this day and also earthquake activity but again in 1985 the thought was that this subduction was happened kind of quiet it was just slipping beneath the northwest and no major earthquakes no magnitude 9 earthquake for instance were possible okay I come to Ellensburg in the early 90s and I started hearing little rumblings here and there about some this kind of unique exotic guy doing his own thing out at the coast of Washington primarily and him finding evidence for a magnitude 9 earthquake and an accompanying tsunami that struck the Washington coast didn't know the guy at the time I knew him now Brian Atwater he's been to Ellensburg a few times and he's a big name in this research so I'm if he's so big that I'm gonna put his name on the board Brian Atwater he was the star of the lecture last spring we spent the whole time talking about his work and I'm gonna spend just 10-15 minutes maybe 10 minutes talking about his work tonight and then we'll move on to another star that has taken out waters work and gone a little further but I'm getting ahead of myself Brian Atwater in their late 1980s and early 1990s single-handedly put enough evidence together along the coast of Washington to completely change our view of magnitude 9 earthquake possibilities in other words he convinced people that it not only was possible but it happened I'll actually give you the date right now since that was kind of dramatic I heard my voice echo just a little bit it seemed like it had some resonance with you so I'm just gonna keep working with that Atwater figured out Atwater figured out that on the night of January 26th 1700 at 9:00 p.m. local time there was a magnitude 9 earthquake that ruptured right off the coast of the entire Pacific Northwest Coast simultaneously in other words there was a massive failure of the boundary between the North American and the Juan de Fuca plate and that underwater earthquake produced a tsunami that washed on to the Pacific Northwest shore along this entire coastline that's a pretty dramatic change in view right from a ten years later this one guy is telling this story so he must have found some pretty good stuff to convince people that that actually happened and by the way I gotta sell something to you I after he did that work and I started teaching his work that was a part of me that didn't quite believe it just a small part that didn't believe that this entire boundary which is called the Cascadia trench that this entire boundary slipped simultaneously and produced this deadly earthquake at deadly earthquake and accompanying tsunami but then 2004 happened and there was a tsunami in Sumatra and there was a rupture off the shore of Sumatra and Java that was exactly this length and produced a tsunami that inundated exactly this length of coastline and killed hundreds of thousands of people so that December 26th 2004 earthquake and tsunami that most of us remember is a perfect modern analogue for what happened on this terrible night 310 years ago okay so we used the present to help us understand the past that water was creative enough to visualize what happened in the past without a modern analogue but now we've got the modern analog in Sumatra okay so what did he find what did he find along the coast that proved to everybody that a magnitude 9 earthquake happened on that date and time he found three things I'm going quickly through this because again this was the whole topic last May he found three things I don't want to use red Sark he found dead trees he found land sunk and he found a sand layer any time in science you want to convince something that is against popular belief you better have more than one kind of evidence that leads to that conclusion right you better have a bunch of different lines of evidence that all come to the same conclusion and this is what Atwater was able to do he found all three of these things and I'll explain them in a second at more than two dozen sites along the Washington Oregon and Northern California coastlines he's a canoe guy he loves being a canoe of being in estuaries working in kind of sloppy muddy places and he found these three things all along this coastline and that led him to the conclusion that this was a regional story and not just something local in the state of Washington or even in southwestern Washington okay so let me elaborate on the three things that he found and again this is not the main target of tonight's lecture we're just setting up the work that was done in the last 20 years that have really gotten me super excited here tonight all right dead trees I'll just I'll give you some beautiful images and animations and living color in a bit but let's try to do it old-school ways here first of all okay so here's a person here's another person or take your pick we're at any of these black circles here but these black dots any coastal place the first spot that Atwater found this stuff was at Coe Palace River you know where that is just follow us highway 12 heading towards the coast and you'll get there there today to this day I was there this summer and the previous summer to this day there are standing trees that are dead and neighboring trees that are alive that happened to be at higher elevation so there's these groves of standing dead trees at multiple places along the shore out water got curious enough about these trees to hire a buddy David Yamaguchi to go out and tree-ring do some tree ring analysis of those trees to figure out when they died and Atwater figured out excuse me Yamaguchi figured out that the trees died pretty consistently between the growing seasons of the year 1690 980 and 1780 studied the tree rings figured out they all died at the same time not just at one grove but all of these groves simultaneously okay that's kind of curious but that doesn't necessarily mean earthquake and tsunami right that could be some biologic seeing some climate things some beetle thing I don't know I'm not a plant person but there's more at every one of those dots the the dead trees are at a place that's lower than a nearby real estate on average by about ten feet a 10 foot elevation change and we're close enough to the coast where this is now in a tidal zone so in other words we are appears dropping land suddenly and killing these trees basically by poisoning them by dropping the roots of these trees into a tidal zone and poisoning them with saltwater where they need fresh water right so that was that waters leap of faith that he realized that maybe this is not a beetle thing this is the land suddenly dropping at all of these sites and deducing that an earthquake caused this land to drop but he still needed some evidence to prove that a tsunami was part of the story now I assume that you know what a tsunami is I haven't defined that but just in case you don't tsunami is a Japanese word that means birth weight triggered ocean wave and we've had a number of these experiences in modern day to know exactly what they are but of course they've been happening as long as the earth has been around earthquake generated wave an underwater earthquake suddenly shifting the land underwater to send that water towards the coast and inundate the coast and wipe out anything that's there now the question is fine you can do that you can create a big tsunami and have it wash onto the land but how do you prove that it happened it's water that came in and then then sloshed away and that's the end of the story is there any physical remain of a tsunami and the answer is yes the tsunami coming from the ocean is picking up material as it surges inland and most of the time tsunami pick ups and they pick up sand from just offshore they pick up sand from the beach itself they pick up sand from I don't know coastal dunes that are nearby think Southern Oregon for instance picking up all that coastal - sand and deposited it inland so the sand layer itself is the actual physical remnant of the tsunami let me draw you a quick picture of what that looks like in the subsurface so I'm going to take this and enlarge it so Atwater then got to one of these groves of dead trees he dug a little hole a little trench and and I'll show you some photos in a second so here's our dead trees the room goes crying as the artist does his work classically-trained look at this alright so here is a typical story of what water was able to find again at each of these black dots right underneath the dead trees he finds a bunch of mud right underneath the mud he finds typically about a four-inch layer of sand right below the sand he finds in many places charcoal pits old Native American campfires and at that boundary right below the sand is a thick organic rich soil layer beneath that is more sand but this sand is different this sand has diagonal lines in it which indicate a sand dune system these are called cross beds so in other words this was an exciting find for us in geology let me try to convince to you why it should be exciting sand at the beach is not a big story cross bedded sand is what you would typically find topsoil on top of that fine Native American charcoal pits roasting salmon on a winter night fine normal but the sand right above does not have cross beds and the boundary between the sand and the soil layer is squiggly is irregular which indicates it was a dramatic event and this sand came in quickly very quickly and it was you the wave was erosive enough to probably true away a bunch of that topsoil also notice that when we get done with the tsunami depositing the sand layer mud is deposited on top and if you think about it that makes sense because what have we done at each of these sites we've dropped it during the earthquake so before we had sand being deposited now we have mud deposited because we're in the tidal zone now we're in high tide instead of before we were high and dry above the tidal zone that's the best I can do for you that's that waters work and everybody took notice and pretty quickly in the scientific community it was all agreed that magnitude nine earthquake have happened at least once along the Pacific Northwest Coast again because we found it at each of these sites all three of those things they tell us it's a regional story okay we okay so far we're up to the mid-90s and I'm proud of myself and teaching this with my freshman at Central it's breaking news in 1994 and we're all current and everybody's great we had a big magnitude 9 earthquake we couldn't quite visualize it but still it was big story okay if that was the end of the story we'd be done with the lecture and that's actually where we quit in May we took a lot more time talking about that story but tonight we want to dig deeper no pun intended all right so that water is still doing his work he's a very important figure but we're gonna leave him now oh are we let me check my notes maybe we're not yet no we're not no we're gonna do one more thing with Brian okay so Brian out water did this remarkable work and after we convinced people that this big earthquake happened he started digging deeper did it happen before 1700 is this a freak thing or is there a cycle of great earthquakes and major tsunami that have struck the coast so dead trees at the surface pretty close to the surface we have our sand layer from 1700 he started digging he found another sand layer he found another sand layer he found another sand land and there was enough organic material in the soil right below that tsunami sand and in the sand itself that he could get actual radiocarbon dates from those earlier sand layers here we go a thousand AD the Year 400 AD the Year 500 BC this is Atwater's work so he did his job he convinced people this was real then the next step was to convince them that there was a cycle here that there was a repeating problem and again this is from being at coastal Washington digging beneath the dead trees or places similar to that and finding a number of these sand layers that are progressively older as you go down so now we can leave that water and he's done his work he says I wash my hands of this situation all right it's up to you now to take the story any further but I've convinced you that we've had at least four great earthquakes that have struck Washington's coast and probably Oregon's coast as well simultaneously tsunamis for each of four of these okay we haven't talked yet about why these earthquakes are happening we'll get to that with the slides and we haven't talked about what's older than this if we have any more information that's what's coming right now I have to say this I'm trying these lectures out for the first time if this is not clear to you so this is sometimes I I mean forget the fact that I'm barefoot it's also unprofessional that I'm looking at slides of pieces of paper and the notes are actually just cartoons for myself because if I write stuff out then I'm like reading every word it's not time efficient okay great so let's let's go on to the next cartoons early two-thousands okay thank you Brian for your work we're done with you now onto the stage the star of the show for tonight a guy with a spectacular name Chris Goldfinger that's his birth name is given name not a James Bond character but a real guy Chris Goldfinger he works at Oregon State University in Corvallis he's a classically trained geologist but he got very interested in that waters work and initially it was a skeptic of that water actually wrote some scientific papers to say that waters work he doesn't agree with everything that water said but he started to take a different approach that ultimately has supported Atwater's work and gone the next step so the rest of tonight is Chris Goldfinger's time and we're going to go into the ocean to find more evidence we're gonna leave the land gonna leave the estuary the coastal area and we're going to go to some submarine canyons off the coast of Washington and Oregon okay so that's going to take a little bit for us to figure out I don't know if you've ever thought about what the ocean floor looks like just off the coast of our state but we've got beautiful maps of what it looks like underwater and there are some spectacular canyons canyons the size of the Columbia River Gorge underwater leading away from Westport or Ocean Shores or take your pick Cannon Beach okay now here comes the challenging part of tonight me trying to draw a submarine canyon can I do it it might take me a couple tries but I'm gonna try anyway all right this is fun let's put Westport Washington up here in the corner this is the actual coast so this is land over here I've got if even that I screw it up I've got the backup of some beautiful illustrations right so this is underwater and what I'm trying to show is a canyon coming from the shallow water down to deeper water in other words there's a continental shelf off the coast of Washington some shallow water under at on top of basically continental crust and then there's a dramatic canyon a submarine canyon think again the scale of the Columbia River Gorge between Washington and Oregon and then it flattens out again down here okay that's my attempt oh shoot I erased my map let me try it again so here's the Pacific Northwest Coast one more time out waters work is going away and now we're leaving out waters dots and we're going to gold fingers dots I should do a different color Gold waters blue a gold finger is blue gold water that's something else so we're off the coast we are underwater actually some of these actually merge some of these canyons actually coalesce so there's there's a dozen or more submarine canyons off the coast of Washington and Oregon that's what I'm trying to draw here okay so I'm taking one of these submarine canyons and I'm trying to draw it here okay so far all right now gold finger says you know what I know that people in back in the 1970s actually got in some research ships and sent some equipment down into these submarine canyons and tried to figure out what was in those canyons or even more impressively what was right at the mouth of one of these canyons and they found a bunch of mud okay not that exciting and back in the seventies the interpretation it was just a bunch of mud from maybe the Ice Age maybe some of the Ice Age floods just brought some of that mud down and some of that still true by the way but the main point is back in the 70s they found a bunch of mud but they didn't really know what to do with it they didn't really have a great conclusion for while that mud was down there and let me be more specific it's not really just mud it's something called a turbidite last week we got into paleo magnetism with Mount Stewart and it got a little a if you're there for a second it might get a little if you write here but I'll try my best for you a turbidite is a sedimentary deposit that you find in a submarine canyon floor from an underwater landslide let's try that again a turbidite is a deposit of sediment and that deposit is the result of a dramatic effect the dramatic effect is a landslide tumbling down this Canyon but the problem is it's underwater it's not a lens like like we had out on highway 10 along Thorpe you know whatever we've had landslides around here right this is a landslide bigger than that but underwater so the real big point is the deposit from an underwater landslide is going to look different than the deposit from a landslide up here in air because you're trying to have a landslide through water cut to the chase what does a Terp what does a turbidite look like it's a package of sediment that finds upwards so in other words we go to the bottom of this submarine canyon and we find a turbidite and here's what a turbine that looks like here's a package of sediment with sand sized stuff at the bottom a little bit less than sand sized stuff above it we're into some silt and then finally we got a little bunch of clay in other words the particle sizes dramatically decrease as you go up and this whole thing right here is one turbidite representing one submarine landslide in one of these canyons everybody with me so far okay it's maybe unclear how we're going to use turbidites to help us understand our history with big earthquakes on land but you got to trust me we're gonna get there okay great so turbidite from an underwater land go to another Canyon find a turbidite maybe find two turbidites from two underwater landslides now there's more information coming and this is also before Goldfinger's time and the people start going well actually this is what happened at water did his thing convinced everybody of these major earthquakes and then goldfinger said I'm not sure I believe at water I'm gonna go back to those turbidites that they found maybe order up a bunch more turbidite collections and see if I can find evidence of these big earthquakes his thought and his big leap of faith is this if we're taking this whole Cascadia trench and shaking it to a magnitude 9 to generate this tsunami certainly we are creating landslides at the same time underwater so the hope is that if we can find turbidites from these underwater canyons and the turbidites all match in each of these submarine canyons that's evidence for a regional magnitude 9 earthquake but if we find a bunch of different turbidite deposits in each of these different canyons then it's just kind of local happenstance and we don't have evidence for a big regional earthquake hope you're still with me just in case you are let's go ahead and look at what was found from goldwater's original work gold gold fingers original work fixed on water gaiters ok great what is he doing now he is drawing sediment cores the he being me nick centner I'm drawing sediment cores you'll see a little video actually brought some video clips with me and one of them will be of Chris with his sediment cores he has in his lab so basically it's a tube full of mud each of this is a corps of mud soft sediment that we're pulling out of the floor of each of these submarine canyons here's where it gets interesting towards the bottom of each sediment core is a ash layer a volcanic ash layer what's your guess for what ash it is Mazama Mount Mazama about Mazama is where Crater Lake National Park is located now in Southern Oregon Mount Mazama right here seventy seven hundred years ago Mount Mazama Blue Ash went all over the northwest including in the southern part of the Yakima River Canyon you've seen that wet white ash layer and that Ash also got into these submarine canyons and every one of these sediment cores has Mazama ash which we can date at seventy seven hundred years seven thousand seven hundred years ago that in itself is pretty sweet but it gets better because sitting right on top of each of these Mazama ashes in each of these sediment cores from off the coast of Washington Oregon in Northern California our turbidites 13 turbidites in that core 13 in that one 13 in that one every core matched with the number of turbidites and what does that really mean to us the number of underwater landslides so it became pretty clear not convincing to everybody but pretty clear in the late 1990s into the early 2000s now that we had thirteen turbidites deposited on top of the Mazama ash in these thirteen turbidites or thirteen landslides under water appear to have happened simultaneously which means there were probably thirteen great earthquakes that struck the pacific northwest coast and 13 tsunami that crashed onto land that water just recorded the most recent four but if he could have dug further underneath those dead trees he would have gotten to all 13 of these do the math with this and 13 and you come up with a recurrence interval the average number of years between great earthquakes and based on this it's 600 years I'll say that again that's pretty important based on these turbidites sitting on top of the Mazama ash where we know the age based on that we have an average of time of 600 years between magnitude 9 earthquake s-- that have struck our coast how long has it been since the last one 310 years right 1700 now it's 2010 so who what a sigh of relief not so fast my friend looks like we're okay looks like we're safe but I got more to say and we're gonna we're gonna change that number just a little bit because we got more evidence coming from Chris Goldfinger still okay oh I'm running a little behind okay let me keep it going I got more for you all right I'm you're racing the board cuz I'm stalling right right right right good I'm going to keep this in my hand because this is stuff I don't know at all wonderful now we're not going to back away from that story but Goldfinger continued to work with these cores and there was a new technique to get Ages for each of the turbidites the only age we had in the diagram I just erased was the ash right but now Goldfinger and his buddies are able to get aged dates for each of the turbidites using radiocarbon of plankton tiny little biology guys in the turbidites and they've got pretty convincing arguments I don't know how they date it specifically that's not my thing but they now can date individual turbidites instead of just counting 613 above a particular ash layer so now we're going to talk about slight differences between these canyons and I'll summarize it the best I can write here we're now into the mid-2000s just a few years ago Goldfinger's continuing to work in this fancy lab he has down in Corvallis okay so I'm gonna try it this way I'm gonna I'm gonna draw two cores representing most of these canyons and I want this core here to represent our turbidites in other words the turbidites off the coast of Washington and want to use this one to represent the turbidites off the coast of Southern Oregon into Northern California okay so up to this point everybody's doing the same thing along this entire coast now the plot gets interesting that things are not quite as simple as we think and there's something a little bit different going on down here then there is off of our coast in fact we now can go down 10,000 feet excuse me 10,000 years ago so this core goes from present-day at the top down to mud layers that were deposited 10,000 years ago and we stopped about 10,000 according to Chris because back 10,000 years ago sea level was lower and so there were storms and things that were actually messing with the turbidites so in other words the signature kind of gets muddy no pun intended down further south right so we only go back about 10,000 we can still put the Mazama in what was that in red before great so our Mazama is still here that hasn't gone away and in the Washington course we still have our 13 turbidites above that hasn't changed either but we found six more below Mazama so a total of 19 great earthquakes off the coast of Washington about this there's 41 turbidites off the coast of Oregon Southern Oregon and California 41 so what do we do with that let's think about that for a second suddenly there's more turbidites there's more underwater landslides off the coast of Northern California in Southern Oregon and again we can identify these individual turbid edge now because we can date the actual turbidite instead of just counting how many there are above a Mazama and now our recurrence interval changes based on these six new guys we found down below with the same duration of time down to 10,000 our recurrence interval for Washington is now down to 500 years it was 600 right so now we're it's been 310 and it's an average of 500 years between great earthquakes these guys over here 41 in the same amount of time recurrence interval of 240 years how long has it been since the last 310 overdue that's scary that's scary this we feel okay about we're gonna play our you know we're gonna we're gonna roll with the punches we're gonna play the odds according to Goldfinger's research and this is literally the last two years now so there's more coming on this presumably but it's looking more and more like these things happen more frequently in the south which means this the current interpretation is this trench does not fail along the entire length every time sometimes it's a smaller segment of the trench that ruptures I think of it like a zipper and actually in Sumatra in 2004 literally that trench opened like a zipper there was one place where the earthquake started and then it ripped open like a zipper along the trench so you can have a trench failure with the zipping unzipping from north to south or you can have a big earthquake where you unzip from south to north and again what I'm saying is the zipper isn't the same length it looks like our Washington's great earthquakes are from a complete unzipping but Southern Oregon Northern California a shorter zipper and again I've got illustrations from Goldfinger's papers to show you that you want to modern it so this is this may be be helpful so ours there are 19 great earthquakes think 2004 Sumatra every time unfortunately think of that as a modern example these smaller earthquakes with a smaller zipping unzipping think 2010 Chile do you remember that earlier this year there was a big earthquake off the coast of Chile in South America and there was a big news huh Bob let's let's go live to Hawaii where the tsunami is going to come in and it didn't quite happen thankfully the reason is the magnitude is a little lower from that 2010 Chile earthquake and it's more analogous to what Southern Oregon and Northern California have experienced multiple times ok I'm going to cut the last page of my lecture but I want to just give you a quick highlight stuff that has come out this year Chris Goldfinger came to Ellensburg and gave a talk in May really humbled nice guy really enjoyed chatting with him by the way that's always a plus sometimes people are kind of jerks right they kind of read their own press you know he's in the press all the time but really fun guy to talk to and he delivered this to us and his sense put out a couple of small papers on this how can I do this quickly I can do it quickly these 41 turbidites in Southern Oregon and California the 15 most recent turbidites here coincide with the 15 most recent earthquakes on the San Andreas Fault in Northern California I'll say that again it looks like this is early information now early work but it looks like there's a potential match between the 15 most recent earthquakes in our submarine canyons off the coast of Southern Oregon and earthquakes along the San Andreas Fault in California which is a different system but up until this point nobody has had the guts or the imagination to link our big fault system offshore with the San Andreas Fault system in California and this is the first time anybody's made some linkages that way it's exciting and damn scary at the same time I'll even add more to that the dating of these turbidites can be down to the year and so those 15 I just mentioned this is spooky now you ready each of these 15 earthquakes in the Cascadia trench happened on average 25 to 45 years earlier than the 15 earthquakes in Northern California and the San Andreas in other words it appears that we have an earthquake up here and a month and a half later there's a big earthquake on the San Andreas Beck earthquake so it's we're thinking Goldfinger is thinking that there's possibly a trigger mechanism here where we load some stress or we transfer some stress to the South which was kind of taboo you know if you deal with the general public and you field questions there's often questions about you know here's that earthquake in Alaska gonna trigger a big failure of the entire west coast of North America and California falling into the ocean and all these things you know which is kind of dramatic and a fun and terrifying idea at the same time up until recently it's just like no no no no they're all insulated isolated things this is the first time we're actually getting to that area which is interesting so if we do truly have this connection we're unzipping the zipper from north to south almost certainly because our earthquakes are happening before the earthquakes in Northern California all right Eric let's crank this thing up we've got a couple quick questions while we fumble with this good question I'll repeat the question and then respond by I don't know the question is it's a good question do we have these 13 still over here you can date them and I shouldn't say I don't know yes the 13 are still here I don't have specific ages all the way through but they're there but because we can date these individual turbidites we found more with this specific dating technique and beyond that I truly don't know so how this matches up specifically in other words how many of the 41 are inter fingered with the 13 that is a question mark so I need to dig in deeper and see if he's got that published I also have to turn on the projector so my buddy Eric here is going to advance the slides and thank you enough so let me get my pointer here lots of good stuff for you that hopefully will accentuate what you just heard which I aim to be thirty minutes turned out to be fifty minutes so whatever here is our fault underwater here's Washington in Oregon we're going to have an earthquake on that fault we're gonna generate a tsunami and that's why we're talking about this whole story next one Eric not a boy so here is a cross-section here's our fault a big rupture have not talked about why the fault disruption by the way I've got a couple animations to help you with that here's our water surging on land and ultimately depositing our layer of sand next one here's that waters work yellow circles here's our spots where our dead trees etc are found and ultimately here's Goldfinger's work on one channel this is old now almost twenty years so now he's got yellow dots gold fingers got yellow dots all over out there next one here's what the dead trees look like next one the dead trees are lower than there which are still alive we look at the tree rings of the living and the dead trees to figure out that the tree died in the winter of 1699 into 1700 next one and if you know southwestern Washington here's Westport ocean shores long beach Astoria Oregon here's the Columbia River coming to the sea and here are some of the sites where those dead trees are still standing this is the famous one called paleis River next one please so here's Bryon's humor saying we've got a Happy Tree than a sad tree than a dead one why because we have an earthquake right here the lad and suddenly drops the tsunami comes in and deposits and next one here's Brian himself working with some of us teachers middle school teachers from across the state I was part of that workshop we canoed out to his site and he showed us in full regalia his work next one please so the dead trees look like this still standing been standing for 310 years dead next one more of them next one please middle school teacher from Tacoma and a dead stump next one here's David Yamaguchi who is also out with us we dug a pit next to one of the standing dead trees and we looked at the root system he also worked with dating the roots Kevin de white from Morgan middle school in Ellensburg next one so that's all along the coast so we say it's a regional tsunami next one do we have more evidence yes we do here's what I tried to draw for you on the chalkboard dead trees are just up here out of the picture we're in Central Oregon now cross bedded sand fire pits from Native Americans topsoil look at this squiggly boundary between the topsoil and the tsunami sand right on top of it that little guy right there that little tan layer is the evidence of the tsunami and then notice that we have tidal mud on top because we've dropped the land ten feet next one please cartoon showing just what I described to you in Brian fashion that tsunami bringing this and grains in next one please back to Brian getting all muddy and cutting a clear Bank for us to look at the layer cake there in the sediment next one now this is all before Goldfinger now right we're not in the water yet these are not turbidites this is just stuff you can find on land so here's Pete from a previous time here's a tsunami sand here's a knife for scale small knife here's title mud and then we go back so if we dig deep we find more of these tsunami sand layers from older tsunamis pretty fascinating stuff next one please Brian and mud next one he had his old pickup with him so we took a section of that little exposure and brought it back to the truck I think he gave it to one of the teachers but here's our mud on top of a tsunami sand on top of some sand other sand next one please close-up of the same thing there's the tsunami sand right there from 1700 ad next one please so from out waters work he's got a handful of known great earthquakes with tsunami going back a couple thousand years that's not good enough for us we want to go back ten thousand which is what we're doing now with Goldfinger's work next one please okay first movie clip using a guy named Rob I don't know him from the Canon Beach area let's see if this works Yorick this is probably a sand deposited by a tsunami that happened about a thousand years ago you see it carries in even a few coarse grains which indicates it was a high velocity wave evidence of the Pacific's destructive force is spread across the landscape in this Marsh at the edge of the Cannon Beach commercial district there is evidence of repeated and violent earthquakes and tsunamis geo seismologists dr. Rob Witter of Oregon's Department of geology and mineral industries pushes a coring device into the marsh by examining the samples he pulls to the surface water can see layers of sediment collected in the marsh over time some of the layers are huge deposits of sand the sand had to be carried here by a giant wave that roared across the coastal plain now occupied by Cannon Beach the ground surface in 1700 was right here this was the top of a marsh much like the marsh we have today then there was an earthquake and then a tsunami rolled in and the tsunami picked up sand from the beach and nearby dune it's a record of that tsunami no one could outrun it yeah this is a big wave okay so here's an animation it's running Eric that's great so here's the tsunami experience the water pulls away from the shoreline everybody runs out unfortunately and then a real problem and so part of this is just public awareness to be fair to Brian Atwater he's now it's mostly much of his time around the world working with governments to try to help educate the populations about how tsunami behaved and getting away from research notice all the sand left by the way from the tsunami next one Eric okay back to our story I forget what's next next one please we have modern examples of great tsunami great earthquakes 1960 do you recall this one in Chile go ahead Eric tsunami magnitude nine and a half the biggest earthquake we've ever recorded the tsunami literally crosses the Pacific Ocean and kills people in Hawaii hours later and kills people in Japan almost a full day later we had telephones in 1960 right we had televisions this is just unacceptable and unfortunately the same drama played out instant in Sumatra in 2004 next one so we have known travel times of a tsunami across the Pacific Ocean from a magnitude 9 plus earthquake next one so here's what we think our January 26 1700 look like at 10:00 p.m. the tsunami is just getting started it has already crashed onto our coast and here's what we think it looked like as it rumbled across the Pacific in the middle of the night 310 years ago just keeping in advance now there you go 1:00 in the morning keep going Eric 2:00 in the morning 3:00 in the morning 4:00 in the morning five six seven in the morning it finally hits Japan and that's how we know the precise date by the way because there's cultural records in Japan which allow us to calibrate or recalibrate backwards to figure out when have happened in the northwest case you were curious about that keep going Eric I think that's about it okay unfortunately the the tragedies continue 2004 Sumatra Banda Aceh next one please 230,000 people killed on that day magnitude 9 and a half here will eventually have the tsunami cross the Indian Ocean and people are dying in each of these countries isn't that ridiculous next one please certainly these people didn't make it I think this is from a camera that was found after the tsunami next one please go ahead and advance Eric so here's the what the tsunami look like traveling across the Indian Ocean again similar to our great earthquakes in the northwest as far as magnitude and and speed travel travel distance and travel speed of the tsunami itself next one devastation after that event please continue we had again a sizeable earthquake off the coast of Chile a real concern of the same kind of death from tsunami crossing the Pacific but the magnitude was lowered that doesn't look like a much lower number but it is when you know the Richter scale and the moment magnitude scale well so it was a smaller unzipping and thankfully less loss of life in Chile earlier this year next one I got a few more and then we're done here's the eyelid skip it next one please so go ahead Eric this is what our coastline would look like if 1985 was true remember that way back then were taught that the subduction happened nice and easy was well lubricated but we now realize that's not the case because of Atwater's work next one Eric our model now is we're getting these great earthquakes and tsunami because this portion of the subject zone becomes locked in other words the subducting plate pulls the edge of north america down with it here's a movie to show you how that might happen this is why we think we have repeatedly great earthquakes we lock this zone we pull the edge of north america down with it we actually start lifting North America's coast and then when the earthquake happens the coast drops the tsunami rolls in and our trees are suddenly dead you want to see that again that's maybe we're seeing again should we try going back and try it again Eric better boy here we go locked and loaded average recurrence interval 500 years of pulling this back before you finally release the spring it's been 310 years of pulling back already thank you next one one more animation go for it same idea lock it drag the edge of the plate down with the subducting plate notice we're going to start to coil this boy eventually until we finally have a rupture and by the way we're going to shake a bunch of sediment loose into the submarine canyon next one Eric OH next one we're running out of time doink next one go ahead in advance great ok next one please even in Japan now worldwide people have bought into our model out waters work and our model have locked and loaded so here's a little cartoon from a Japanese version go ahead and advance it and one more oh all right tsunami next one please okay keep going so we go to gold fingers work for our last few minutes together next one please to the canyons we go here's what some of these underwater canyons look like here's Washington and Oregon so the blue are the canyons where we're pulling out these turbidites next one please the canyons look like this so here's the coast we're out waters doing his work here's our underwater Canyon and our underwater landslides depositing turbidites is that what you visualized I don't know how you would based on the diagram you had on the chalkboard next one here's an animation of it next one kind of a cheesy animation let's go underwater and big earthquake and trigger an underwater landslide that's what we're talking about to produce a turbidite deposit next one so back to this picture next one and here's this underwater landslide happening in water so the biggest stuff settles first and the water basically holds the fine stuff in suspension and so by the time that tiniest clay sized stuff deposits it's on top of the deposit this is what a turbidite looks like this is evidence for one underwater landslide next one next one Chris Goldfinger next one I drafted up on the kitchen table last night as I was putting the last part of this lecture together it's not very professionally done but what I wanted to show you is a sediment core from today back to 10,000 years ago these are all 19 great earthquake turbidites so in other words washing tens turbidites and what I want you to notice is that potentially there are clusters of great earthquakes with up to a thousand years of nothing so it's true that right now we believe that there's an average of 500 years between great earthquakes but is this part of a cluster in other words are we not necessarily going to wait 500 years this next time that's where the real drama comes in so perhaps there's more coming with potential clustering of these great earthquakes so that this might be part of our future in the next hundred years I certainly hope not ok thank you so much for coming out tonight I really appreciate

Channel: Central Washington University

Views: 63,595

Rating: 4.8416243 out of 5

Keywords: geological, Central Washington University Organization, Ellensburg Citytownvillage, Central Washington University, Geology (Field Of Study), Flood, Cwu, cwu geology, Central Washingtion University, earthquake, Cwu Geological Sciences, Storm, Geology, nick zentner, Ice Age Floods, History, tsunami, Education, Zentner Geology Lectures Downtown Ellensburg, science

Id: QAtheBYU9Xs

Length: 59min 9sec (3549 seconds)

Published: Wed May 01 2013

Reddit Comments

[u/[deleted]]

Oh man! I can't believe someone knows about this. I have an actual Tsunami tree. I collected them in Gray's Harbor County Washington. It, and a number of other ones where found on a berm that that was the furthered inland extent of the the Tsunami of 1-26-1700.

I have had scientists actually come and core this one -- It seemed easier to bring it to them, then to bring them to it. Its healthy and thriving in my garden now.

[u/graffiti81]

Also, if anyone enjoys geology, volcanism, and the like, Mr Zentner has a great series called "Downtown Geology Lecture Series" where he talks a lot about old and new ideas concerning geology of the PNW.