 Welcome to another Science Exchange with UWA. This is where we want to promote the relevance of UWA research and its teaching activities to you all. My name is Kirsty. I'm a lab manager with the Science Faculty here at UWA. I'm excited to join with you today to learn how geomorphology allows us to experience earthquakes. So before we do get started, I will present our speakers to you so we actually have Professor Myra Keep who's there on I think you're right. Myra is a structural geologist whose research focuses on how and why rocks do form. They're interesting include earthquakes and related hazards in WA both onshore and offshore and what controls them. We also have Sean. He's a PhD candidate here with the School of Earth Sciences. He began his time at UWA doing a Bachelor of Science in Geology and Earth Science and currently as a PhD student his research is investigating earthquakes in Western Australia. So I'll hand over to these two lovely people who will take you through a quick presentation. We'll be presenting for about 30 to 35 minutes and then after that we'll ask them all the hard questions on what they're presented to us. Without further ado you guys take it away. Thank you very much. Okay so we're going to try and do earthquakes in about 15 minutes with cake. So we'll see how well we go. Most people probably know that we have earthquakes at plate boundaries. Most people have heard about plate tectonics and you've all heard about the Pacific Ring of Fire. Now that's a zone where we have a lot of earthquakes. There's also a lot of volcanoes. It's where we have a lot of subducting plates with one plate sliding under another one. Australia is quite a long way from plate boundary. To get from Perth up to the plate boundary, the Pacific Ring of Fire in Indonesia, we've got about 3,000 kilometers to get to the plate boundary in the Southern Ocean. We've got about the same. So we're quite a long way from a plate boundary. So our kind of earthquakes are called intra plate within a plate. The earthquakes are on the Pacific Ring of Fire called inter plate. They're between plates. Ours are within a plate. But all earthquakes are caused by the same mechanism which is stress caused by plate tectonics. So you've got these plates moving around the globe bashing into each other causing stresses and that is the cause of every earthquake on the planet. Now believe it or not there is something called the world's stress map and this is this is one version of it. I wouldn't worry about all the different colors. It's just the density of data. Now that's telling you where the greatest stress is on the planet at the moment and you can see the Pacific Ring of Fire is very well represented all along South America and around North America and parts of Europe, little bits of Africa and a little bit in Australia but nowhere near as dense because we are so far from the plate boundary. We do have stress. It does cause earthquakes but we're not quite in the same category as Indonesia or Japan or California. The earthquakes we do have though are all the more interesting because we don't know really why they occur in a lot of places. We're a long way from a plate boundary but we do have we have had some big ones and Sean's going to talk to you about some of them including mekering and the central slide there at the top is a view of a mekering false cut from the air. The slide you're seeing on the screen right at the top is also from the mekering earthquake and the middle one at the bottom is also from the mekering earthquake and the other two on the left are just examples of what happens when you break materials because in order to get an earthquake you actually have to break something. You have to physically break it, break all the bonds, the two pieces no longer fit together. They no longer join together and that usually happens with a sudden catastrophic release of energy and that's the release of energy is what we feel as earthquake waves so we need to actually just really break something. Now some rocks will bend and some rocks will break and I've got a little demonstration here. I should have said cake and biscuits. I have two different types of Anzac biscuits. I've got Anzac biscuits and I've got Anzac biscuits. You might wonder why am I feeling a little hungry perhaps perhaps not. Some of them though, now these are both Anzac biscuits, there's one from each packet but they're going to behave differently. They're both made of exactly the same material. We've got the same ingredients, maybe slightly different proportions, maybe baked at different temperatures or for slightly different lengths but essentially the same material but if I take this Anzac biscuit, I'm sure you can see that, I can apply a stress to it and this one is just going to bend. It doesn't actually break and hopefully you can see I've got a nice bendy biscuit there and it's actually just bent, it hasn't broken so it's accommodated, it's just sort of you know it's accommodated the stress, it hasn't actually broken. If I take the other Anzac biscuit I can't do the same thing. Now again it's exactly the same material, it's still an Anzac biscuit, it's still got sugar and flour and oats and butter and I don't know what else to put in Anzac biscuit, syrup probably and this one does not want to bend. I can't bend it, I really have to force it. Now I have to put a lot more stress, I have to really apply the stress to break it and that's it. I've severed the bonds, I've catastrophic broken it, the two halves will never again join so this is broken and that would have released some energy and so the two biscuits behaved quite differently and I had to put a lot more stress to break this one than I did for this one even though they're the same stuff. So the way the materials, especially the rock materials break is very much related to what they are and how they form. The other thing that's quite important is just how fast you actually apply that stress and I've got one more thing, is one I prepared earlier. This is a piece of silly putty, you might have seen this stuff, you can buy it all over the place. So if I apply a stress very very slowly to this it just kind of stretches and I'm applying the stress very slowly and the whole thing kind of stretches out and is just going to you know keep on stretching forever but if I take exactly the same material and I apply the stress much much faster it actually breaks okay and I've got those two ends, they've completely broken off and I've severed all the bonds, I've had that catastrophic failure, the stress, the stress went right up my arms and started rattling around my brain, I'll probably need to lie down a bit later. So that's so we call that the strain rate, just how fast you break something. So if I do that again maybe with a smaller piece, a much faster application of stress will just break all those bonds. So when earthquakes occur we have to break the bonds. Now what you've got in this slide here on the top left you've got an example of a rock that has not broken, we've applied the stress but we've applied it maybe slowly or maybe the rocks nice and hot and mushy, maybe the rocks on the top left were a lot more like my soft chewy Anzac biscuit. The rocks on the top right there have actually broken, we've applied a fast stress, we've severed the bonds and it's a release of energy when you sever those bonds that gives you the shaking that we have. So when we break a rock material, when we have earthquakes we've actually broken a rock, we've applied the stress, we have to have more stress, the amount of stress that we apply has to be more than the strength of the rock material but we don't just leave a gap, we don't just leave some sort of space in the middle of the earth there, you can see all of these pictures are pictures of faults, they're something that has actually broken, we've created, we've broken the rock material, we've created a geological fault, one side is slipped away from the other but they're all still sort of touching each other and sealed by something. You can see the one on the top left there has a little bit of quartz veins sort of pasted alongside the fault, there's another vein on the top center, the one on the top right has actually got a lot of clay smeared along it, there's another vein on the bottom right and on the bottom left side there you can see a fault plane, you can see the orange layer on one side is much higher than the orange layer on the other side of the fault where the person stand in the bottom there, you can see it's slipped down, it's moved but it's still touching, the fault surfaces are still touching each other, the bonds have been broken through. So what happens in nature is we get a lot of vein materials, any time you have a fault you can get fluids running through them, it's the same kind of process that would actually form the gold deposits and the nettle deposits as well, they become a fluid pathway and fluids like they'll have lots of lots of quartz in them and the quartz often sort of crystallizes out and gives us nice quartz veins like the slide on the bottom, the picture on the bottom right there. So it's a bit like nature's glue, the rocks will heal themselves, you will break them, they'll slip but then they will seal themselves again. The trouble is once they're broken it's like breaking the handle off your favourite mug, once you've glued it back on it's never going to be as strong again, so you'd be a little wary about having your favourite cup of tea in the broken mug just in case that handle falls off. So quartz and other fluids which precipitate on fault surfaces and veins are like nature's glue and they're going to hold things together but they're always going to be weak. Now this is where the earthquakes occur in Western Australia, there we go I've just highlighted where they are, now what you're seeing on the right there is a geological map and the colours represent different types of rock and we're just going to have a look at the the rock types in Western Australia and how they concentrate the earthquakes. So that's a geological map of Western Australia and I'm just going to highlight some of the main bits for you, that's the first bit now those two big pink pink bits are the in the south that's the Yilgankraton and very in the far north there that's the Pilbara, these rocks are what we call Archaean in age so they are 4.6 billion to 2.5 billion years old see some of the oldest rocks in the world, some of the oldest in Australia, say that out loud 4.6 billion that's 4,600 million years old, they're some of the earliest rocks on the planet so they form the core of Western Australia. Now surrounding those you can see the bits in blue and brown and pink and yellow at the bottom those are what we call the age of those is what we call proterozoic. Now that is slightly younger but still very old 2.5 billion years to 541 million years old this is still largely before life started on our planet for the most part. I've coloured the proterozoic ones in slightly different colours because some of them are sediments some of them are from volcanoes and magmas and lavas so they all they've all got slightly different compositions just like our hands like biscuits and on the very left hand side there that blue colour that's much younger that's what we call panerozoic it's 541 million years old till today and that's what forms the basis of the geology of Western Australia so we've got all of these different blocks of different age all sitting there glued together by faults which have veins and other things on them and so we're going to make a little model of that. Now the yield gone crate on itself even though it's really old 4.6 billion years it's divided into lots of separate bits it's not just one bit it's lots of separate bits of continent that crashed into each other back in the Archean so there's quite a few different recognisable elements even within that old bit and we're going to be playing around with those so you can see there's some every way we've got a change in colour there on the right hand side between the green and the purple and the orange we've got some big fault breaks and these are really old deep faults that have been around almost since the beginning of our family aren't you saying because they're still in the Archean so what we are going to do we are we're going to build a little model of the geology of Western Australia I'm going to basically be looking at the south part so I'm going to have the big pink bit in the middle with all the faults on it a little bit of the blue to the left and the yellow around the bottom which is the album Fraser so down with the Albertine to Esperance and I'm going to be making this model using a whole bunch of different types of delicious food items that I found in the supermarket this morning so we're going to switch cameras now and I'm going to show you the model and we're going to start playing around with some of the stresses so hopefully you can all see my cake model at the moment yes we've got the cake can excellent see this only happens inside right cake can really so what I have tried to do let's just try and get you oriented a little bit so this direction here is north okay so I if I was walking up this direction I'd be walking up to brew heard this sitting around here which appointments are sitting around here albany would be down here this is I'll be coming around to Esperance along here and this big swage of stuff in the middle is that pink blob the Archaean Yildan Kraton now what I've done I've sort of half finished the model to try and save time I've got some different bits of fruit cake so I've got some dark fruit cake and some light fruit cake you probably can't see the difference but believe me they're all delicious and I've got some dark and light fruit cake making all the different bits of the Yildan Kraton and you can see this pink stuff here I've put some frosting on to act as a geological glue to act as those veins those materials that would help glue the faults together so that's our old bit this is our key in light here now down here for the albany Fraser I've used a lot so you can see I've used some Lamington's okay Cam there we go find out where my angles are I've used some Lamington's I've stuck them all together with some frosting and that's going to represent the albany Fraser which wraps around the Yildan Kraton here part of the proproshoic and over here I've got my Perth basin with I've got some beautiful Madeira cake over here that you can see so it's still cake just but it's a different type of cake so we'll have different properties just like my hands at cookies I've put some icing sugar over the top because we have sediments so I'm just going to put a little bit more sediment this on the face and I had some spartes on just so you could see how things are moving they just sort of act like like markers so you can see if and when things are moving so when we then start to apply a stress a tectonic stress from plate tectonics we can try and see which of these are actually moving okay so there's a there's a few more and I'll just I'll just liberally sprinkle some all over the albany Fraser belts smarties and the albany Fraser one I'm going to get really highly technical and tectonic stresses are usually in plane because the plates are moving around the outside of our sphere so I'm going to use no expense spend I'm going to use my never before attempted on that live zoom I'm going to use my cake mallet to impose a stress on my cake model and we're going to see which directions so first of all I'm going to come in from the south so here I am just to get you oriented again I'm in the southern ocean albany is over here earth is over here and I'm going to see what happens if I apply a bit of a stress all of these faults are cut in there lined with some beautiful frosting there and we're going to see what moves if I start applying the stress you can start to see my albany Fraser bits moving I don't know if the case cameras think you can see all squeezing together not surprisingly the interesting thing is exactly what's moving it's the bits between some of my faults in the albany Fraser the bits between my lamingtons are moving but it's not really affecting the you're gone so much and Sean's got a bit to say about that when I when I finish this if I come over this side again never before attempted on a live zoom so I'm coming in from Adelaide I'm going to whack him to Western Australia as you do on the Tuesday afternoon I'm just going to hit the edge of the out of the albany Fraser look what happens now see my albany Fraser is starting to move out the way I hope the K cam is picking that up but it's really moved everything every time something moves on this model we have an earthquake okay so I've managed to cause a big gap in here and I've destroyed a few lamington sorry casualties and as I push this it's actually these bits of the albany Fraser that are moving these faults are moving a little bit but it's actually quite hard if I'm to move something by forcing it head on is quite hard the easier way to do it the break you come in slightly from the side and if you come in slightly from the side things have an opportunity to slip out of the way so if I come in down here now we're attacking albany with the cake mallet on the cake cam here we go and now we're going to start move and again see now my albany Fraser is slipping away the other way and I'm beginning to move some of my faults in my yule garden you see those smarties moving a little bit so we're completely deforming western Australia and it's these old faults some of these faults have been here for four billion years or two billion years and they're still the ones that are moving today and did you see I don't know if you caught it but all of the albany Fraser stuff starts slipping sideways out of the way and Sean's going to have quite a bit to say about that and my last one well we just we just apply the stress to uh sort of Gerald turn them we I think we I think we just destroyed perv actually um so that's those defaults are the ones causing the earthquakes there they're the ones that are reactivating and now we're going to hear about a real life one actually happened uh relatively recently I'm going to hand over to Sean that concludes the earthquake segment of the presentation um you're all earthquake enthusiasts at this point but we want to make you ambassadors of the subject um so we're going to end on you with some um more up to date information uh that isn't billions of years old um I'm going to talk about one of the most recent earthquakes that happened in western Australia so I'll just take you 52 years back into the past um if you haven't already heard of the Meckering earthquake it's worth going and googling and looking up um it is the uh one of the best examples of interplate earthquakes in the world um and it spontaneously hit the town of Meckering about 150 kilometers east of Perth 52 years ago and it completely demolished the town um so in the next slide you can see that uh it was a huge earthquake uh magnitude 6.5 which is very big and as you can see on the right hand side there uh the damage radius uh the felt radius was massive encompassing a very large area of western Australia and as you can see earth is very close to the epicenter there um so that kicked off a whole generation of earthquake research in western Australia um with the obvious big question of uh is Perth um at risk of large earthquakes um if you don't know too much about the Meckering earthquake great place to start is with your grandparents because um it was a big festive occasion in Perth uh anybody that you ask over the age of about 60 has a great story to tell about it most likely. So moving on um these just some photos of Meckering and some of the damage that happened you can see the highway uh over there um was uplifted uh dog for scale as you can see um and the railway tracks were bent quite considerably as well so it was a fairly damaging earthquake um and continuing that's some of the damage uh that actually happened in the town um the entire town was completely wiped out so if you can imagine that occurring in an area closer to Perth um the effects could be quite devastating uh but that's not actually what I was supposed to be talking to you about I'm talking about the uh most recent earthquake that we had in western Australia um which formed a very small hill uh formed big thrills for me the small hills in the landscape um and that's actually a picture of me sitting next to uh western Australia's newest hill um playing the guitar actually what I wanted to say I forgot to say this before Meckering earthquake is also pretty important because it's the only earthquake that I'm aware of in the world that has its own beer and they brewed this for the 50th anniversary of Meckering earthquake they called it Richter Eil which is a great job you know that's the whole reason I was holding that bottle so um September 2018 let's go just back a couple years uh a lot of earthquake activities spontaneously started happening in western Australia you will have remembered it from the press uh there was a lot of talk about it for example you might have even felt one but the major one was um the Lake Muir earthquake which occurred just south of here um near Albany uh there were three big events there was uh the main one was a magnitude 5.7 earthquake which is quite big um and in the next slide you'll see that it was felt very widely around Australia on the left hand side that's the uh the first earthquake um and you can see there's a lot of felt reports that came out of Perth um and then the second aftershock had generated even more reports um probably because everybody was in the mood for reporting earthquakes at that point so they got on to it um so I'm just going to quickly go through what happens when an earthquake occurs in western Australia from a research point of view so uh on the night of that earthquake occurring I was contacted by Geoscience Australia um and they were basically looking at some of the uh satellite data in the area uh that's able to depict if there's any um changes in elevation very small changes in elevation um so we got some data in from the satellite and that data on looked like what you can see on the right hand side there um and that basically allowed us to to determine that there had actually been a change in surface life in the area that the earthquake occurred the little schematic diagram that I put together just below that um showing that we could expect about the 30 centimetre rise in the topography of the area um next slide is showing oh yeah there we go so second step was to um pack your dad jump in a car and drive down to the area and this is why people do geology to go get into beautiful areas like this and do a bit of good work um and uh basically analyse the earthquake and see what the damage was and see what happened um the earthquake itself occurred pretty much in the middle of nowhere right in the middle of a big farming paddock uh which is great um because uh it was a really beautiful place to work um there was one farmstead just nearby and those are the photos you're seeing now uh the earthquake did do a little bit of damage it um managed to completely destroy a water tank and it cracked some walls as well um it uh the first earthquake um knocks some very valuable plates off a farmer's um mantelpiece uh so we put them back on the mantelpiece and then the second earthquake came through and knocked them off and broke them properly um but moving on this is the this is the very exciting small hill and look I assure you everybody interested in earthquakes all five people in Australia were totally riveted when they saw this photo so that's the that's essentially Australia's newest hill it's about 40 centimetres high um we did we did rolly collies down and we drove power delivery right um you can see very interesting a nice geological feature there the fissure at the back it's kind of like a little mini version of the one they flew the plane through in 2012 um but uh that's a very signature um uh indicator of a thrust uh fault scale and we uh we also you know as part of the analysis process we also flew a drone around we collected some um orthophotos and we put together a um digital elevation model which basically just shows the very fine detail topography of the area and you can kind of see there's a line there in that that bottom image which is showing the length of the scarf which is a good five um five kilometres in length so if you can imagine a five kilometre area of land being lifted by 40 centimetres there's a lot of energy involved in that there's another photo of the scarf and the third step is to actually go in there and do a bit of manual labour um which is of course the not so nice part of the field trip um we spent about a day digging this this trench uh for the purpose of as the next slide will show um just seeing what happened uh in the cross section um in the landscape around the fault scale and this uh image illustrates that this is what um earthquake geologists spend a lot of time doing called uh paleo seismological investigation basically seeing how the top soil and the top's geography in an area um has moved when the earthquake has occurred and as you can see you can quite clearly trace out um a thrust fault through there which proves that there was actually um a brand new scarf being formed in the area and that's just a great little schematic diagram that we put together as well very clearly showing the fault plane and that be sure at the background and there's another photo um of the small hill uh intersecting a little track in the area as well um so we traced the the length of the scarf we spent about five days walking around in the field um I was basically being remote controlled by geosciences fairly iphone um just trying to go where they told me to to to find the scarf and trace it out um and we managed to basically line up different segments over about five kilometers to form uh sort of the the general shape of the the fault scarf and the whole reason that we're doing this and we're trying to trace out the scarf is because we're trying to work out some reason that it's occurred where it has and why it might have occurred in the shape and location um and one of the the main um angles that we approach that with is by looking at some of the pre-existing faults that are already in the area so we use a dataset called aeromagnetic data which basically without getting too technical um allows us to see what the geology looks like beneath the um soil in the area um and all the white lines that you see on this image here are just faults that probably do exist in the area that we've traced out from the aeromagnetic data and as you can see right in the middle of there the fault scarf that's formed from the earthquake aligns very closely with one of those lines so that suggests that maybe um what's happened here is a very old fault that that has existed for millions of years um may have been reactivated in um in the recent stress field uh to form that earthquake and to relate it back to the cake cam if i can do a cheeky switch the earthquake occurred about here where this little red smarty is um and notably that's very close to the boundary between um lambington orogeny down here and um the main fruit cake of australia uh so what what really happened is um you can expect if we have a bit of east west movement which is currently what's happening in australia you can clearly see as mario demonstrated that that lambington is moving relative to um fruit cake and that is a very simplified cake version of what might have happened in the area that formed out of the earthquake so um that is the most recent fault scarf that's formed in western australia but as you can see from this image on the left there actually um a whole lot of other ones that exist um every black line there uh most likely represents one or more ancient earthquakes that might have occurred within the last 10 000 years or so um and that shows us very clearly that there's been a lot of seismic earth uh seismic activity in western australia and a lot of big earthquakes uh have actually happened uh before we began recording earthquakes and uh considerably uh further back before we started actually um observing them ourselves uh so the big question is uh we saw that the lake mur earthquake the most recent one occurred on a fault that previously existed so maybe if we map out a lot of the faults in western australia we'd be able to um we'd be able to identify faults that could be more prone to activating that would give us an idea of where future earthquakes might occur um i i thought it would be a good idea to try doing that um and i started mapping out areas uh where there are lots of old fault scuffs in australia um as you can see i tried a small area there just east of earth and there were so many faults and so many lines i just gave up um pretty quickly but the moral of that story is that it's very difficult to actually identify any area that might be particularly prone to earthquake risk because there are so many pre-existing structures in the area it's hard to actually pinpoint one that may be particularly prone to rupturing um so that that concludes the lake mur um segment and just before i leave just some unscripted rambling about uh the the big questions in earthquake research in western australia right now um so you don't need to look at this uh table two too deeply but trust what i say when i say that about four meters of topography has been built in the last 50 years due to earthquakes which doesn't sound like much but if you consider that that activity um if that would have been going on for the last one million years we would have expected to see about 20 to 40 kilometers of topography in western australia which we just don't see western australia is very flat so one of the big questions are um where are the mountains why why isn't there a lot of topography in an area that's building quite a lot of topography right now um and that may be suggesting that uh the seismicity in western australia has actually increased considerably um in just the last uh 50 to a couple hundred years the other big question that we're talking about right now is if the seismic activity is actually moving around western australia um myra said before that there's the the main belt of seismicity near birth um which is shown there in the red uh but just in recent years in the last few decades it's actually started moving to various other areas and there's been other swarms starting up so that's been another big question that we're we're trying to look at right now is why might seismicity be moving um but as my final slide will demonstrate we're really not sure what's happening um or what's causing it uh but in 2020 the obvious candidates are 5G, Kanye West, something to do with Donald Trump, all the classic conspiracy theories that are popping up now I'm sure are also causing earthquakes in western australia um I think I've got one yep there you go and if you'd like to see some of the earthquake activity that's actually happening right now um you can jump off that website uh and and monitor them yourself anyway that's all that I've got to say about the topic so thank you for sticking around um and try um try injecting a bit of earthquakes into your next party conversation thank you so much guys that was so interesting uh I know I've learned a lot I probably haven't touched on any uh geology and earthquake type stuff since my first year at uni quite a few years ago so no that was really good um all right well let's get into some questions we do have one here one from Brady who said great talk um and wants to know if there's a risk of damaging earthquakes in the Perth area and if so our building's built to withstand such quakes the answer to that is maybe and not really there's always a chance even though the recurring earthquake was felt in Perth uh there was actually damage to buildings in Perth the cathedral had some damage Perth is not really earthquake engineered especially the downtown area if you know we divided between the hills and the flat part and the flat part is a big sand bit more built on sand you know you haven't looked at any house being built in your neighborhood it's just on sand so if there were as it were an earthquake that did cause more shaking in Perth we would probably have a lot of damage because none of our buildings are designed for earthquakes and in fact if you think about a lot of buildings especially big buildings down downtown what have they got underneath them big carpark sometimes even multi-storey so you've got huge buildings built on big empty space and you know the soft sediments will cause a lot of liquefaction especially in the Perth city area as it's reclaim land so yes we probably wouldn't be in a very good situation but the likelihood is is not high but if it did happen it wouldn't be pretty I don't think there's much comfort in knowing that we're built on one big sand dune in Perth so might just all slide into the ocean if it's not going to be rising seawater it might be an earthquake um all right so we've had another couple come through see how many we can get through just um questions of time so I'm from Deborah she's asking um large aquifers affect earthquake patterns such effects they uh earthquakes have a big impact on aquifers um and the vice vice versa is probably true uh for the lake Muir earthquake um it actually uh really messed with the groundwater um in the area and um about 150 kilometers away there was reports of um uh water bores on farmers properties um leaking water and flooding paddocks so that's an example of an earthquake really mucking around with um so when you say messing with the groundwater do you mean that it changed the level of the groundwater or yeah so it would have um would have changed the level of groundwater within the aquifer in the area uh and that um caused uh some catastrophe in other areas um very far off in that case interesting wave so suddenly increasing pressure so suddenly increasing fluid pressure from the earthquake so those those disturbances and groundwater would be temporary then they'd go back to the order okay okay yeah that makes sense okay um another one from ben here um he's saying to you both for your talk and he wanted to um ask if you know how old these reactivated bolts might be do we know an age is the one potentially from um the one in 2018 or no no idea but probably probably something like the proto result or this result or something like that so very old you know on the scale of hundreds of millions of years can I ask a question off the back of that how would we usually date an earthquake like how would we look at dating those kind of faults is there a way to look at that you you can try one of the problems we have is it's very difficult to take any earthquake and link it to a specific fault especially as we can't see most of them because we need geophysics to see through all of the vegetation you can try and date some of the coating on some of the faults you you might be you might get lucky there you can try some optical dating of certain minerals but most of the time you're just having a look at the rock mass and you have to realise that so some of those faults have been reused many times since they were formed so a fault that's two billion years old could have failed three thousand more times since all right probably have time for one more question guys so I'll ask um Don's because he's been sitting there for a little while um how deep was the epicenter at Lake Newark and the Meckering earthquake uh it was very shallow well Meckering was basically on the surface underneath this emittery um of all places the Lake Newark was also very shallow probably about two kilometres or at least within 10 kilometres but a requirement to make a fault scarf on the surface is um it's important for the earthquake to actually have occurred very shallow so that's a good indicator of a shallow workplace okay great look we've only got two I think quite quick questions here so let's get to them um the first one is from um G Giles who was in relation to when we were talking about the Aquafar um asking would an earthquake have similarly marked up the nearby Lake Muir when the earthquake happened at Lake Muir and then after that Samantha wants to know is a tsunami likely to happen with the type of quakes we get in WA we went around and we we had a look at some of the bores near Lake Muir um but if there were if there were changes to the actual lake itself they would have been very subtle and nothing was reported or we didn't observe anything drastic in the area to do with the hydrogeology um but likely given that the aquafa was disrupted something small would have happened in Lake Muir and now in order to get a tsunami you need to have the earthquake off shore so you need the earthquake to happen underwater so when you offset that scarf and Sean said five kilometres of 40 centimetres uh mass uh so you need to be able to uh offset that uh that scarf underwater in order to do that you need to have about magnitude 7.9 and we haven't had anything that big in WA so all of our earthquakes the good news about our earthquakes is for the most part they're quite small magnitude three is three and a half what was looking like five point seven five point seven so so we don't really have anything much bigger so five point seven or five point two or six point five in WA is enormous for WA but nowhere near enough all right great thanks for that guys thank you so much for taking the questions and thank you everybody for uh putting those questions through to our speakers for today and just so you know I think the cake can look not only delicious but also very informative we were able to see some great movement there so um thanks for coming to the table with something so different to present to the audience uh stay safe stay healthy and we thank you for being part of today