"New Mexico's Dynamic Geology" - W. Scott Baldridge

to be here and I want to encourage any of you to ask questions at any time as we go through so northern New Mexico in fact New Mexico in the southwest I love it I've I've kicked around there for a long time here for a long time and I hope to convey some of that to you one of the things I do want to emphasize especially for the younger people who are here is that many of the problems that we face as a society today are science-based and so if you're interested in earth science there's a need for people to go into the field and there are a whole variety of opportunities it can be planetary science that not qualifies as the earth science if you study Mars we count that as through science it all gets folded together and I have colleagues who work there not on Mars but they're actually working on directing the rover for example right now that's all their science certainly alternative energy is partly earth science natural resources of all sorts ground water it's a big one that's earth science and there's all different kinds of directions you can go with what we broadly sort of called geology I think now we tend to call it more earth science but I'm not specifically going to talk about those kinds of opportunities but I hope you'll see them as we go along in this presentation so I guess ok so I want to encourage all of you any of you to ask questions as we go on so any time just raise your hand and ask a question or call-out so I've organized this presentation as sort of a virtual field trip I didn't really know what people were interested in particularly so I said well I'll just sort of go to different places that I think are important and that interest me and they can become topics for discussion first want to talk about geologic time I'll just say a few words about it because that is the concept I think in earth science is that people have the most difficulty with and I'll tell you as you become a professional or scientist geologists your concept of change really changes I mean if you think that 100 years is a long time forget it and so we do talk about geologic time differently and we think about it than so many other professions one example of that is is 50 million years a long time 50 million years well maybe it's only 1% of Earth history so you're just starting to think about time so so that's one thing I want to and I have a geologic column that sort of shows that the length of this column the vertical height of it is the 8x I'll get this so we start from today up here and 4.5 or 4.6 billion years would be the age of the earth so that's how old the earth is in New Mexico and in the southwest we see about this much of it almost two billion years of time there are rocks exposed for that length of time somewhere in the southwest in New Mexico for example up in the Sangre de Cristo's we have rocks there are over a billion years right there so yeah a billion years it's beginning to be a long time even a geologist calls that old rocks mostly what I want to talk about today is just sort of in this upper part of things right in here but if but if you have questions about other things then we'll get to it well that's a really good question and we can talk about it more later but I'll give you the short answer right now the Earth's crust has formed in pieces over long periods of time and probably the original crust has been was destroyed during bombardment and things like that so it's formed in pieces it's still forming today and in the North American kraton if you go up to let's say Canada that's those rocks up there very old some of them are approaching four billion years old but the crust was formed in successive stages this direction so good question it's not the rocks that we see at the surface are not necessarily four billion years old yeah good okay so that's geologic time now the other another important concept is the land surface that you see and that we deal with and everything what we call the physiography the shape of the earth's surface can be much different in age from the rocks that are on it or in it for example if mountains are uplifted and they're made of very resistant rocks they'll stay there and I can say okay those mountains over there a billion years old rocks are but the ground surface here could be just a few million years old so when we talk about the age of the rocks it is can be very different from the age of the surface the physiography that we're dealing with and I this slide will show you a little bit about that this is New Mexico you recognize an apple I'll master this before the talk is over I'm sure okay so here's New Mexico the state of New Mexico and it's been divided not by geologists because the geology doesn't always correspond it's been divided by physiography into these names that may be familiar that the Great Plains here labeled southern High Plains but as part of the Great Plains that extend all the way to the missus Sippi River and that's characterized by fairly thick crust it has generally been very stable you get small earthquakes here and there but really not too much has happened to it and those rocks that are that formed the upper crust are really only a few hundred million years old then new New Mexico is divided by what we call the Rio Grande rift and I have another diagram later that will show that better but what we call a rift is a place where the Earth's crust has been pulled apart and broken in the middle in a series of faults and it's generally a low area and not so stable necessarily and of course these mountains are you recognize the Rocky Mountains they're a relatively late feature to the Colorado Plateau which extends over quite a large region here part of it's in New Mexico it's a piece of the kraton it's a piece of what's now the great plans that's been broken off and rafted away been broken off by the rift and then we have the this big massive volcanic field down here the mughi on daffle volcanic field it is it's a series of super volcanoes but it's an older area it's about these were formed mostly between 35 and 25 or 20 million years ago so it's pretty eroded and now it's mainly when you go up there it's beautiful territory but it's mainly a high plateau kind of rolling and with canyons but it's the rocks there are you know 2530 million years old this is well for example Silver City would be somewhere down in here this is in the southwestern part of the state the Gila wilderness the Gila it's just a gorgeous place good point I should have been okay I'm glad we have a great audience here here the hem has mountains right here these are the southern part of the Sangre de Christo so Santa Fe is right in here Albuquerque would be right about here this range to the east is the Sandia Mountains and you see that they kind of come down the sides of the Rio Grande rift in bits and pieces and then down here when we get toward so Socorro would be roughly in the middle of the state probably right in about here in Las Cruces is down here and El Paso down here the mountains the the main mountains here pretty much bound the flanks of the rift that I'll have more to say about that also but what I do want to point out is the physiography in and in some cases the rocks are different in all of these different volcanic provinces but the most active area of New Mexico is up-and-down the rift and of course the rift continues way down into Mexico and into West Texas before we lose it all the way to Big Bend big then you still have these valleys that are and the valleys are broken they're formed by dirt falls and the Basin and Range this extends there's only a piece of it here in New Mexico but of course it comprises Southern Arizona and Nevada and so forth the Basin range is a big physiographic province lots of faults active today so what is a rift I've given you a quick explanation already but here's a here's a block diagram that sort of explains what it is the outer part of the earth is called the crust you probably know that and its thickness is anywhere between 40 miles and 15 or something like that but on continents is usually a little bit thicker than under oceans and the crust is relatively cool and it therefore brittle and so it's easily pulled apart by plate tectonic effects or even by circulation in the mantle below it below the crust is what we refer to as the mantle and yet is it extends anywhere from 35 kilometers 30 to 20 miles or so down under southern New Mexico to a couple of hundred kilometres down and it's it includes a little bit of partial melt so many of the volcanic melts that come up originated here in the upper mantle like pretty much all of them what's what's important here though is when you have extension an extension can form for a lot of reasons like like breaking the crust of a candy bar right you get this nice chocolate coating on it and you pull it apart and it breaks in flakes and pieces but the middle part which is nougat it's sort of sticky that's how the earth breaks apart to when it does you form faults like these and we have lots of lots of faults the mountain ranges of Sandhya's the Sangre de Cristo's and so forth are parts of these uplifted shoulder pieces the reason that we have a river the Rio Grande flowing through New Mexico is it has gotten itself not surprisingly into this valley it's actually a series of valleys and it's caught in there and so that's why the river is where it is and of course for reasons that this shows pretty well you have these faults and you have hotter material down here often rifts are places where we have volcanoes or even just on the flanks sometimes of rifts so you find often lots of volcanoes and in New Mexico we have lots of young volcanoes and more probably still to come oh yeah let me back up here this is a picture of Albuquerque probably the South Valley and it kind of shows now of course rifts low places are always places where you get lots of sediment flowing into them so the sediments have created a nice flat valley for but the rocks that are exposed up on the flanks of the mountains like on top of Sandia Crest really are down here somewhere underneath these sediments that fill the filth of the Rift Valley they're down here so that's they're separated by a lot more distance than just the height of the mountains probably at least yeah there's there's probably several kilometers a couple to three miles of structural offset beneath parts of Albuquerque especially around Bernalillo yeah yes there's a the topographic relief between the valley here and Sandia Crest is really only about 5,000 feet so there's two or three or four times that structural offset yeah so that's what a rift is and of course as you pull apart anything the flanks sort of rise and that's why they back tilt they tilt away from from the valley and you see that like Sandia cast here is a similar picture from the caballo Mountains a little bit to the south and as you see in many places along along the rift you see them on Sandia Crest you actually see them in the sand and sunray decreased those two the main part of the the range is really ancient rocks a billion years or older in most cases with a little bit of the limestone on top which is around 300 million years old and underlies a much broader region but the fact that the mountains have raised up like that is what exposes those sedimentary rocks so that's a very common thing to see and that's what forms the rind of the watermelon on the Sandia Mountains the San Luis Valley this is also in the rift and a lot of probably many of you or of all of you maybe have seen the Rio Grande Gorge here and people think that's the rift oh I understand a risk that's not really the rift that's in the rift but the rift is really this entire valley that's the floor of the valley of the rift and here are some of the flanks to the west the toussis mountains and off to the east would be the Sun greater christos and these are volcanic volcanoes small volcanoes to the north so this is really a cool picture and so if you see the Rio Grande Gorge you can say well we're in the Rift but it's just a gorge cut through all those basalts all those lavas if I use some of these terms and just have to raise your hand and say what does that mean okay so why are rifts important and I draw in a little bit because they are important well one of the big reasons is rifts often or where the water is water flows to the low places that is collected there and if you look at the three largest cities in New Mexico where are they they're in the rift Santa Fe Albuquerque Las Cruces and so on and so forth that's where must much probably most of the settlement is is in the rift and that's where so many of the ancient peoples lived to is in or on the flanks of the rift where there was water another reason is because rifts are in little places you get all these sediments washing in and you get gravels and sands which made great aquifers so rifts are often places where you have good groundwater aquifers minerals are typically exposed in the escarpment because you're looking at different rocks on the flanks older rocks so that's often where the minerals are and mineral companies know that yeah we preserve older rocks beneath rift sediments and they're often better preserved than those on the flanks just because they're buried so often we need to look at the older rocks or want to look for the older rocks or oil companies know to look in the older rocks for their resources so riffs are often places for exploration and the same thing for that's often where energy resources are concentrated either in or along the plain of rifts because the faulting will carry deeper groundwater which is often hot and so many times they are places for geothermal resources alright now let's go look at things so here's an example of the Great Plains to the east and I know you've probably most of you've seen there you drive through it a lot but we generally it's flat it can be rolling with canyons cut in it but it's it's old core North America the rocks underneath are a billion years old and older and you get layers of sedimentary rocks dominantly buried so there's not much action not much faulting not much mountain building within the within the Great Plains or anything like that and so that that's that's that physiographic provinces mountains by the way are the eastern part of the flank flank uplift along the Rio Grande rift they're not way out on the Great Plains ok by contrast the Colorado Plateau lots of action here same part same kind of crust as you find on the Great Plains but it's thinner and it hasn't been battered up too much but there's been a little bit of deformation on the Colorado Plateau and volcanism here for example is Shiprock which is around 25 million years old or so and it's the throat of an old volcano so the vent and it probably did that would be up here above the peak somewhere when we see all of this it's what's left when you've eroded the softer ground away away from it the these rocks here are much more resistant to erosion so you basically just lowered the ground surface all around it that's why it's still standing and that's a good example of what I mentioned earlier that the physiography is very different from the from the age of the rock here is now again think of it the this time yeah yeah and it's a great place because again it's on the Colorado Plateau so it's been broadly eroded but these rocks are about 50 to 70 million years old depending on exactly where you are and they're being exposed by erosion you can see dominantly they're flat lying rocks and get these funny hoodoos wherever they you get out something that's a little more resistant to erosion it protects a column of rock beneath it but again we see the rocks exposed on the Colorado Plateau someplace is deeply eroded by the real god by the Colorado River or tributaries and so you get this beautiful landscape and there's more action there because it's been elevated it's already the average elevation of the Colorado Plateau is about 6,000 feet but as you know it can range up to 10,000 feet or higher when you get over there and Utah Nevada along the edge of the the different colors it's almost always due to iron and when you get a hydrated iron like limonite or gur tight or something like that it's yellow or when you get redder colors it's really a it's it's rust basically it's iron oxide just just literally like rust and some of this red some of this red is chalcedony is just silica sio2 often takes a reddish color because of impurities in it and some of it if you go out to the best eye is clinker because they're live coal layers in this rock and many of them have burned naturally the coals teams have burned coal seams will burn for hundreds of years and you get this stuff that looks like lots of pebbles and things all heated together stuck together and it's clinker in fact this area was all scheduled to be ripped up for coal mines fortunately got saved okay so let's move on to vulcanism I showed you that rifts are often places where we get volcanic rocks lots of them here is the rift now extending from central collar actually for its extends even further north where it becomes narrower and narrower but this map shows it from central Colorado all the way down through New Mexico steps around like this and all the way down into Texas and Mexico so the yellow represents the young rocks the sediments in the rift the brown rock are the ancient rocks like the Sangre de Cristo's this here the Sandia well he let start again these would be part of the song raised right here they run up here and this is the Front Range the Sandia's and the Manzano's and so forth here and then we have other pieces sticking out through here but the purple rocks are all volcanic rocks and they're all young ish young means mostly less than 15 million years here in this particular diagram but there are older ones many of them are within the rift but interestingly here in this rift many of them run obliquely to it and that's its own story but when you're in here for example this is the hennas mountains and then the Saros Del Rio the little group of volcanoes just west of santa fe and albuquerque volcanoes are right in here they're just a little tiny little volcanic feel I'm going to show you some of these volcanic fields we'll take a look at this we'll take a look at the hem as we want to look at Carrizozo volcanic flow here - that was a flow that's around ten thousand years old and it probably flowed armed for probably 20 or 30 years or more just a little bit at a time using down the valley really interesting thing so let's start with the Albuquerque volcanoes just because probably most of you are familiar with them they're a bunch of one-shot deals we call them you get one shot maybe for a few months or maybe a year or two it would form about oh you would form a volcano and usually a lava flow a lava flow would go in different directions sometimes if you're there and walk around you can see them but in but they're now covered pretty much with soil and so forth and so you don't really notice them so much there's a whole series of them along aligned along a couple of different fractures so you know that there's fracture control or perhaps a faulted depth they probably went on and spattered for who knows maybe a decade or so we don't really know how long it took for them to to erupt but they kind of splattered away and probably never ever any of them will have RuPt again so it's what's most common in New Mexico and all through the Southwest you get these sort of cinder cone fields they're often called cinder cones or spatter cones because you get lots of groundwater that's entrained in the mouth and it throws up the cinders and it's probably like a sheet like dike of lava coming up to the surface and then it'll never erupt again then we have Carrizozo flow that I mentioned the source of it there are two separate vents back here and it flowed on for decades and you get a series of flows because it up didn't pulses and one would flow as the next one would flow on top of it and perhaps go a little further and so it's quite a dramatic feature five to six thousand years old as best it can be dated it's not very well dated even yeah it's hard to sometimes to date these young lava flows this is a fairly iron and magnesium rich kind of mass of lava that we call basalt and it's fairly fluid so when it's hot enough and the slope is steeply steep it will flow almost like water and it'll form these very typical what we call ropes of flow like like pouring molasses sometimes on a flat surface you get these ropes if it's sticky very characteristic here is another basalt lava flow out at Grant's if you haven't been there it's a great place to go it does involve a bit of a walk it's called generally the region's knowing known as El Malpais or as ranchers say al Maleh pi whenever a rancher here says I'm mal a PI or something you know he's talking about a probably a basaltic lava flow they called this bad land and couldn't ride their horses in it the cattle get into it they probably stay there a long time and it formed this particular flow formed us a la lava tubes as lava channels open up and flow often they'll roof themselves over it's very efficient for them in a way because it keeps the heat in and then they the lava can flow much further and there's around 20-some miles of lava tubes in just this part of El Malpais now national mine they're in this public land often the roofs of these tubes will collapse and that's what's happened in this case I'm standing in the lava channel itself in a place where the whole top has collapsed and all the blocks you see in the foreground are the pieces that have fallen off into it but what's so interesting is it's a big tube you could put a house in there and along the sides of this I don't have photographs here but along the sides of the tube if you were to turn around and look in the other direction there are more of these collapses but you can see what we call bathtub rings - which represent different levels of flow flow would probably the last time the pulse of lava went through it it'll form crystals and try to begin to roof over and then the level will fall and it'll form another ring and you can see those very prominently these are horizontal yeah these are their wheeler well 50 feet you can sort of judge by this one person standing off and looking into the abyss in this if you get yourself down in here it's very difficult to walk among all these blocks but some spelunker is often go into these lava tubes and some of them go for miles there's a whole flora and fauna of its own in these tubes ok so here's another kind of volcano I don't want to say too much about it because I'm already probably running out of time but this is kilburn hole and this was driven not so much by lava there was lava down there but by gas it's a deep is something that's situated from very deeply probably had a huge amount of water in the magma and also carbon dioxide so it blew a hole and you get a lot of ash and so forth around the sides of it but it didn't really create much in the way of lava flow so it's down by las cruces but what it did do was it pulled up pieces of the Earth's mantle and you see this green rock here it's not really that big it's mainly olivine the main component of this kind of rock is olivine and you can come up later and see these I have two samples here of basaltic rock with one of these we call them xenoliths as eknoll if comes from the Greek I guess meaning a strange rock something that's out of place in the rock which hosted it but when you know the size of these things and of course then you can look at the weight of them and and so forth compared to the melt they're heavier than the melt that come from the mantle they're dominantly olivine there's a Pyrrhic see there's two piercings in them and then usually some a luminous phase like spinel or sometimes garnet if they come from very deep they're gorgeous and people have studied them very thoroughly really to understand the Earth's mantle one way we can learn about what the mantle is made of the deeper part of the earth so I invite you later to come up and and certainly look at these you certainly welcome to handle them but they're heavy very heavy so be careful also I hadn't I probably won't say too much about it but the rock in the middle is a piece of a lower part of the crust of the earth so it has a different chemistry a different chemical composition but from studying the size and weight of these xenoliths and so forth we can estimate the flow the upward rate of flow of these lavas to and it basically any of these eruptions that we see like the Albuquerque volcanoes or any of the Malibu fields they'll come up in a matter of days to a week or two from from let's say 30 miles down they I don't know if that's fast or slow to you but to me it's pretty fast for those things to come up okay so finally let's move on to the hamos you recognize this this is the big kid on the block it's a super volcano and it is it was a real disaster at the time that it erupted this whole thing here is the hem is Martin's with vias caldera that's the actual collapse feature from which the eruption occurred and in the snow of course in this photograph really emphasizes the valley quite well these various domes these are lava domes that erupted after the main eruption and collapse of the crater I have a figure that will show you that the flanks of the mountain all of this area here almost almost all the way around it like this is these ash deposits that erupted and originally the initially in one of these eruptions probably the plume of ash and gas we'll reach the stratosphere and go around the whole world this one certainly did but much of it as the as the plume collapses then you get this hot ash that rolls down the slopes of the volcano and those are enormous ly destructive that's what wiped out Pompeii and other places like that they can be very hot 600 degrees they can move very fast certainly 50 60 miles an hour they'll go over topography they take out everything and they can go for miles and miles no good question very good question thanks for asking the hema is a volcanic field is this whole thing and it's been building for probably at least 15 million years we know that because some of the older rocks in there we can date and as it was building it depends on the rate at which the melt is coming from the mantle if it's coming very fast it'll build one big one big chamber like blow if you can imagine blowing up a balloon before the air can get a leaky balloon if you can blow it up really fast I mean there are no such things because when balloons break they catastrophic but I don't know if it's growing again I'll come to that but it has erupted twice already in these big yellow stone type eruption this is a supervolcano it's not quite as big as Yellowstone but it's one of a number on earth I'll show you more about this so here's another kind of a physiographic map of it right here from a different angle and you can see again here's the collapsed part of it and then since that time probably there was a ring fracture ring shaped fracture all along which the cork essentially collapsed and then you get later a few million a few thousands to hundreds of thousands of years later you get various small eruptions that come up along that ring and in some cases and it is true of the hem as the floor that will push back up to so that has happened in this case I guess I should hurry here but anyway that's what's happened and this is how one of these forms you get a shallow magma chamber which means it probably has to you have to have a lot of filling material quickly you build a volcanic edifice like that it never was quite this big over the hem house and then at some point it begins to collapse basically it means that the roof the rock roof the shallow crust is not strong enough to support the weight any longer of the volcano up here and as you partially empty it it begins to collapse and probably it collapses simultaneously with eruption and then eventually you run out of steam you run out of molten rock you run out of water which is driving the whole process in a way and then in many cases crater lake Oregon would be one small example you'll form a crater lake in there we know that vias caldera here had one or several lakes over a period of time it would you'd have a lake probably build a dam or something and it would break the dam and flow out and then there were two or three lakes in there over a period of time now erosion is cut back in far enough that there is no lake it's because it's because you're in fact this eruption evacuates the magma chamber it's like taking a soda bottle shaking it up and I've done this with teachers you you offer to let them open it and kind of point the bottle toward them a little bit you know it's gonna happen the water in the soda bottle is full of gas as soon as you get any kind of leak coming up from the chamber you begin to break the rock the steam leaks out and you and then the lava starts coming in you get it you dropped a plume which this doesn't really show but it's yeah you just evacuate the thing let me move along here so what's happening there now under vias caldera some years ago I and a number of people we had support from dealey we had support from the laboratory we had support from the National Science Foundation the US Geological Survey did a series of seismic experiments where we put out instruments recording instruments and listened to natural earthquakes that's what these are supposed to be worth quick rays coming in and basically I'll make it really simple here just to keep it just to keep moving here but you can you can measure what you're actually measuring is the arrival time you know that an earthquake has happened over in the Pacific Ocean for example or someplace like that you measure the time exactly of when each instrument records that way of and when you do that you can then back calculate the velocity of the wave where the velocity is slow that indicates that the you have the waves have intercepted hot rock or even molten rock where it's faster you missed it and so we did that and the result was we had three areas of slow waves one near the very surface which was a caldera filled with all the landslides and there was all the stuff in it that was about 17 percent long we had a big region here which was about 23 25 in some places even slower percent low and so the only thing that makes sense to slow up the seismic waves that much is mount rock type alone won't do it and then we have some down here which could be mount or it could be intrusions of basalt at the interface between the mantle and the cross so that and for a number of other reasons we think that it's a dormant volcanoes not extinct is dormant it probably will erupt again and actually here's another argument for it here my colleagues who have been working there a lot recently oh so let me just tell you a little bit about the time and these eruptions he's too big caldera-forming eruption occurred 1.6 and 1.2 million years ago these were the big eruptions but the caldera has has erupted at least 25 times since then small eruptions little ash flow events domes and things so there's no reason to think this isn't going to erupt again and the repose time between the latest was 4,000 years ago 40,000 years ago but it's been doing that for a million in a 1.2 million years so when's the next one going to be well you decide we don't know we do know that it's most likely to erupt again there will be precursory symptoms certainly they'll be probably small earthquakes they'll be steam vents there will be a warning but it would be a bad thing it will be a bad thing when it happens even if it's just small and you get a big plume of ash and so forth at least so there's we think there's magma there now it doesn't mean that it's capable of erupting if there's only a little bit of mouth and lots of crystals it's very very sticky probably more interrupts okay so let me switch to false does anybody know where this is if you've seen this photo lava jato it's great it's a great photo it's a very interesting place this is the old road this is the old Camino Real I love Camino Real after it was improved and you can still drive it or you could last time I tried it it's not easy but my point in doing this is to it's a place where all of us of course then the modern highway is a couple of miles south and you notice that especially in winter but it's not like it was but there's something like 600 feet of offset from the top of La Bajada mile to the ground at the bottom so okay that's a lot maybe but we've done enough work out there off pretty much with students doing seismic work we know that there's really structurally there's there's about 10,000 feet of offset of any given layers along that fault that that escarpment represents at the top part of the La Bajada fault and so 10,000 feet of course what's happened with the river there the lower part of it has been filled and when you make a hole that deep of course it's filling constantly but there's 10,000 feet of offset along La Bajada fault right at that point so it's been a major fault it's one of these faults it creates the rift basins so what happens when you get faults and you get earthquakes so what one of the things a lot of people think we don't have earthquakes here in this part of New Mexico I want to disavow you of that notion we do get earthquakes we haven't had any really really big ones that I know of since you know in historic times but there have been quite a number including in 1918 there was a magnitude 5 or so as best we can estimate it in surrealist in dulce in 1963 there were a series of small earthquakes and one substantial one that's estimated now at between magnitude 5 to 5.5 not big by California standards but we're not at the edge of a plate here either we're in the middle of a plate and this is sort of character characterization of places like rifts and it's characteristic of places like rifts where you have lots of faults and of course if you have lots of small ones like twos and threes and fours which we do and 5 & 6 which we occasionally do means you're at risk for 7 to 7 and higher and they're the ones that begin to get serious so this is the area of just to show you where we are here this is the Colorado New Mexico border right here farming tongue I think is right there Durango is right there I put the letters on bigger because this map as it was published was kind of hard to read Durango is their Chama is their Dulce is dead center there's little all the most somewhere in here in Santa Fe is down here so really people here probably didn't perceive it it did it wasn't a huge earthquake but it did some damage so yeah 1966 January 23rd that I think it was kind of late in the day and just to show you this for fun this is one kind of earthquake wave this is a surface wave that just travels along the surface these are the ones that shake a lot and so if this were your house right here watch how it moves sideways and up and down and that does a lot of damage to houses that's called a love wave it's a kind of surface wave there are various kinds okay so earthquakes Kap can and do happen here this was kind of a crappy picture taken in 1966 by a fellow from I think the Colorado Arizona the Arizona the Colorado Geological Survey got down here really quick and and interviewed a lot of people and looked at some of the damage just looks to me like a store and it's probably characteristic of the kind of damage that it did it damaged almost every house in Dulce and the schools for some reason in particular but you can see all these cans and so forth probably lots of broken bottles and so forth no deaths so but it wasn't big earthquake but it was a good Socorro is pretty much the earthquake capital of New Mexico lots and lots of earthquakes often they get swarms of earthquakes there there's a history of earthquakes all the time in 1906 there were there were there was a whole series of earthquakes that happened the three biggest ones are showing here magnitude five point almost five point six five point eight and then a six point two that's getting to be serious and it did some damage this is the courthouse and the Masonic Lodge and if you look at it you can see here's a wall that broke out and part of the roof collapse there certainly been collapsed and part of this building here to knock down chimneys and it did various things like that and of course masonary buildings are the worst kind that's why the codes for putting steel in masonry buildings are as strict as they are and adobe is probably the very worst so but a magnitude 6 earthquake will do damage if it's at all close to the surface so and certainly sakura has had a lot of earthquakes since that time small ones they happen almost all the time and the reason I don't have any slide for it but let me tell you the reason that we think it's happening we think there's active intrusion of magma happening now coming up part of it may be plating out at at a depth of I have to convert always from kilometres to miles but 15 miles down in some places is probably shallower and what geologists think and I'm always skeptical of things real hard but I think it's probably right that there's a growing intrusion in the upper crust now of a basaltic melt probably a magma of some sort comes up a little at a time over a period of time there's a lot of reasons for thinking that there's could be volcanism there in the future okay one of the things I forgot to say at the beginning is I want to really give you a feeling for we do live in a dynamic environment here the Colorado Plateau and so forth and I've talked about earthquakes and volcanoes but another thing to think about I think about this a lot is the climate has changed a lot - I don't mean short term I mean long term since the ice age and if you look at Central New Mexico here and this is true all over the west places where we don't have water now used to be wonderful lakes nice beaches good vegetation lots of animals humans living there and so forth and this shows the area down by white sands playas white sands there even well white sands is on the shore of this former Lake Lake Lucero and it was a closed basin the water that ran into it couldn't get out so it just evaporated and it made these fabulous gypsum formations the gypsum is now caught up in fact it's here's a somewhere I have a picture of it but the gypsum is being scoured by the winds now and piled up along the shores of what we now called white sands but we had lakes beautiful lakes and the plains of san agustin I was here by Lordsburg that's why we get so much dust being picked up it's partly the very fine lake sediments so when the wind blows a lot like today you can actually get brownouts on the interstate not a good thing small lakes all through here in the Estancia area and so forth and many many other places Arizona California Utah Nevada lots of these and they were the climate really was quite different than much whiter much cooler we find these glacial age animals and we certainly know that Clovis culture and Folsom culture people lived around these not not 30 million years ago but but certainly 12 and 10 million years ago for sure they did so that again we climate is dynamic too and it's a part of geological processes yeah here's here's a better view of okay so Lake Lucero is the modern playa Lake Lake Otero was the previous Lake and much bigger and certainly some deeper not huge here's white sands in here and here's a picture of Lake Lucero at the present day when it happens to have some water in it but anyway so yes it's a great place and it really indicates just how much climate has to do with our geological processes and okay so thank you and I'm happy to take any questions I know we've had a few Geron that's great but if you have anything now now's your chance please feel free to come up and look at these rocks before you leave at least be careful if you can have them there hands on but don't drop them on your foot that'd be fatal Yellowstone and Long Valley California and the hem has mountains are three of I think only ten or so big supervolcano type volcanoes in the world today in the last million years so you know when you think I didn't mention this with the San Juan Mountains or the mountains down my silver seat at Silver City they're old calderas and they're not uncommon on earth but they're thirty million years old or 25 they're not going to erupt again Yellowstone probably will there's magma under there now Long Valley has had it scares as we know with intrusions of probably basaltic dykes coming up but not erupting and we think there's melt under vilas caldera now so long Valley is a bigger it's the biggest of the three for sure it has erupted three times and actually in kind of a succession bias caldera by contrast has erupted twice so far and they've been confocal sorts of eruptions the the big caldera collapses have occurred one on top of the other Yellowstone what more did you want to know I okay but there are there are other ones that that are big towba volcano in the Philippines is a huge volcano they're not rare on earth humankind has never seen an eruption that large never things like even Mount Saint Helens eruption or on the Greek islands or what's the one crocodile that's thank you that's what we're trying to think they were small potatoes I mean they were nothing they were I think crocodile was something like one or two cubic kilometers of lava liest caldera was probably at least 300 the two are sheets together so these are big guys the effect global climate it depends on how much sulfur they have some are worse than others sulfur seems to make could have the greatest influence on on the temperature and so forth but yeah question as climate change is increasing the volume and the way promotions this slightly that's a really good question so the question is is the changing volume of the oceans does it affect the plates I'd probably say it the other way around the plates are changing a lot just by their own driving mechanism which is really negative buoyancy they try to sink into the into the deeper earth and so on a long-term long time frame probably they are what effect the volume of the ocean basins and it's not just the big plates but you get little plates even pieces of plates that change and things like I should answer another question here before I forget about it too because someone asked a different question that relates but the plates their relations are shifting a lot all the time on different time frames so I don't really know the answer to that exactly but the driving mechanisms the heat flow the turbulence of heat the mantle convex on different scales too so that affects things quite a question about crust crusts continental crust is formed in subduction zones that's the biggest environment by which new crust forms so as plates are subducted basically the water is driven out of the rocks is what it amounts to you get arcs of volcanoes we call them the we call these lines of volcanoes like Central and South America that's a magmatic arc but you get them off in the oceans too like in Japan and the Philippines those are arcs of volcanoes too and all of that volcanism over periods of time what's spectacular at the surface are the volcanoes which you don't see underneath are the big magma chambers that never come up that's C and then you end up shoving them on to the our against continental crust that's where we form crust and it's been happening well we don't know how long because we don't know when plate tectonic started but it's been happening for two or three billion years at least on earth now it's sort of the related to the earlier question please it's fracking there's no question about it I mean there's it's been well documented by the US Geological Survey they've published it even the oil companies get that one yeah and it comes from from waste disposal not fracking of wells has gone on for a long time but not with the volume of water that's being that's used now so there's no question about it yeah one more it's also a big fault zone anyway so I wouldn't doubt the perhaps oil and gas could have had something to do with that I haven't ever seen that in print it could be I wouldn't argue against it but it is a big zone it's a continuation of the zone that comes up the west side of the Sierra Nacimiento which is probably the second most active earthquake zone in New Mexico and it really doesn't that doesn't have to do with earthquakes because if you look at the epicentral locations they're in a narrow belt right along the west side and that has to do with pulling apart again of what had been a an area that been pushed together that threw up these Nacimiento but now it's pulling apart and so it's very active and Dulce is right on that same trend he goes right up to Pagosa Springs so that's what I know about that that's right so the question was is it the actual fracking that causes all the earthquakes that we now read about and everything or is it this disposal the fracking itself is very not sure what the pressures are but it really you can see it with sensitive seismometers you can go in there and you can see these magnitude minus 1 and minus 2 and zeros and ones and two magnitude but they don't do much the fraks themselves the fractures are not very long they're not going to last that long for one thing but what they know is just by people have studied them we've had there's been a student at the laboratory you've studied I mean you can you can see the distribution of the earthquakes they always center around the disposal wells and you can relate it in some cases to the actual pumping event itself too so there's there's a lot more coming about that but I think yeah so it's mainly the disposal of the water that's doing that those powerful pumps really putting a lot a large large volumes of water under pressure yeah yes

Channel: Santa Fe Alliance for Science

Views: 29,675

Rating: 4.715847 out of 5

Keywords: geology, new mexico, science, santa fe alliance for science

Id: fGS4nqsC3b8

Length: 60min 1sec (3601 seconds)

Published: Thu Mar 09 2017