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STARS OVER THE SALTON SEA This image was taken by Michael Shainblum at about 7:30pm on November 12th of 2012; the Andromeda galaxy is the bright spot in the top right of the image. It is a 5 image vertical panorama taken from the Abandoned Navy Pier on the western side of the Salton Sea, a rift lake on the San Andreas Fault, in California’s Imperial and Coachella Valleys.
The Salton Sea
In 1905, workers were constructing a canal to carry water from the Colorado River on the eastern border of California to the fertile agricultural areas in the Imperial Valley when something when wrong. The waters of the Colorado broke free and almost the entire volume of the river poured into the low ground at the bottom of the Valley. The Salton Trough sits over 70 meters below sea level, only a tiny bit above the elevation of Badwater Basin in Death Valley, so water easily poured into the basin when the canal walls broke.
This wasn’t the first time in geologic history that the river had filled the Imperial Valley. The valley floor is filled by Colorado River sediments; for the last several million years the river has bounced back and forth between flooding the Imperial Valley and entering the Gulf of Mexico, with its direction determined by which flow path was easiest. As sediment built up in the delta, the river would naturally shift its course to flood the imperial valley, and as sediment blocked that spot it would shift again back to the Gulf of California and its delta.
The river flowed into the basin for more than 2 years before engineers could finally send its huge flow back to the Gulf of Mexico. The flood gave birth to an inland lake known as the Salton Sea.
For decades, the Salton Sea actually stayed mostly fresh. Tourists from the nearby cities of Los Angeles and San Diego would visit the shores to swim in the waters and migrating birds found a delightful water source on their route. But over time, the chemistry of the water changed.
The Salton Sea was flooded by the Colorado, but the water in the local area was able to sustain it. Flood irrigation from nearby farmlands and input from local streams kept the Salton Sea water level close to constant, but those waters also carried salts and fertilizers into the Sea, increasing the salt content and eventually leading to algal blooms that would kill huge numbers of fish.
The Salton Sea’s tourism industry died decades ago as the waters changed, but the situation is more worrisome today. California spent years in drought, and beyond that water for farming in this valley has become gradually more precious due to increased demand and climate change.
The decline in water supplied to the Salton Sea risks turning the waters into a desert or a disaster like Owens Lake to the North (see here:http://on.fb.me/1ytht1g) or Lake Urmia in Iran (http://on.fb.me/1BvJUjE). If the waters of even part of the lake dry up, it will expose bare, salt-covered sediment that will easily be picked up by the wind. These sediments could easily turn into a major source of air pollution throughout the southwestern United States if they’re allowed into the air. That level of air pollution would likely turn into a multi-billion dollar environmental disaster.
The lake has been gradually contracting for the past several years, exposing dry and salty ground particularly at the southern tip where the polluted "New River" enters the lake after flowing through agricultural areas in Mexico and the US. The State of California was originally supposed to develop a remediation plan for this area as early as 2003, but no one wants to spend money or give up their access to water supplies, so more than a decade passed with no agreement between the various agencies and landowners who would have to participate in controlling pollution in this area. Finally, just last month several stakeholders struck an agreement to begin diverting some water and developing wetlands on areas that are being exposed as the lake shrinks - a first step towards managing the drying of this basin.
-JBB
Image credits: EPA/NBC News/NASA http://nbcnews.to/1L5sobA
“Imperial Valley, California, Earthquake October 15, 1979. Imperial Fault 0.8 kilometer south of McCabe Road (4.8 kilometers northwest of the southeast end of the fault). The double trace of the fault here outlines the depression between echelon strands that was flooded by leakage from the canal liner (foreground) broken by the October 15 displacement. The distance between the berms is about 23 meters. View is north. Photo by M.J. Rymer, October 23, 1979. Figure 93, U.S. Geological Survey Professional paper 1254.”
USGS Denver Library Photographic Collection Library ID: jce00008
The current state of the Salton Sea system in California - already an ecological issue due to decades of pollution flowing into it, there is now such high demand for water that within a few years, the lake itself is expected to begin rapidly shrinking, which will expose the entire area to everything deposited on the bottom.
Fluid flow in a geothermal system
This is a shot of the Salton Sea in California. The Salton Sea is a dying, polluted lake formed in what is called the Imperial Valley, a deep valley below sea level surrounded by mountains in Southern California and Northern Mexico. That valley is formed as part of the Pacific-North American Plate Boundary – the plate motion steps to the right, jumping between the Imperial Fault to the South and the San Andreas Fault to the north. In the process it creates a spreading center – it works like a spreading center on a mid-ocean ridge, except here sediments from the Colorado River and the surrounding mountains have buried the spreading center.
The spreading in this area, pulling apart the crust, has allowed warm mantle rocks to rise upwards and melt. These magmas have intruded the Colorado River sediments, metamorphosing some of them and leaving them hot enough to be used as a geothermal energy resource. Several power plants have drilled a 1-2 kilometers deep into these sediments and tapped hot fluids at depth to generate electricity; the steam in the background of this photo comes from one of those plants.
Scientists at UC Berkeley have seismic stations set up in this area to monitor motion on the faults and those stations can also be used to study properties of the rocks. In 2012, there was a swarm of earthquakes in the Brawley Seismic Zone, about 15 kilometers from here. The scientists found that these earthquakes actually triggered changes in seismic properties of the rocks where the geothermal companies extract their hot brines. The seismic velocity of these rocks slightly increased when they were shaken, suggesting that fluids were suddenly able to flow out of the rocks more easily. The scientists hypothesized that the nearby earthquakes triggered opening of new fractures that allowed the fluids to more easily flow out of the hot rocks. At the same time, there were new mud volcanoes formed nearby, consistent with new fractures forming and new paths for fluid to reach the surface.
-JBB
Image credit: Geo Thermal https://flic.kr/p/LvFKYb
Original paper: http://advances.sciencemag.org/content/4/1/e1701536
Video exploration of California’s Salton Sea, including some of its history and how it looks today - basically an abandoned, desert, environmental disaster. Original caption:
Deep in the desert of southern California sits one of the worst environmental sites in America—a former tourist destination that has turned into a toxic soup: the Salton Sea.
The sea was born by accident 100 years ago, when the Colorado River breached an irrigation canal; for the next two years the entire volume of the river flowed into the Salton Sink, one of the lowest places on Earth. The new lake became a major tourist attraction, with resort towns springing up along its shores. Yet with no outflow, and with agricultural runoff serving as its only inflow, the sea’s waters grew increasingly toxic. Farm chemicals and ever-increasing salinity caused massive fish and bird die-offs. Use of the sea for recreational activities plummeted, and by the 1980s its tourist towns were all but abandoned.
The skeletons of these structures are still there; ghost towns encrusted in salt. California officials acknowledge that if billions of dollars are not spent to save it, the sea could shrink another 60 percent in the next 20 years, exposing soil contaminated with arsenic and other cancerous chemicals to strong winds. Should that dust become airborne, it would blow across much of southern California, creating an environmental calamity.
The perfect combination of winter rains and spring temperatures transformed California's Anza Borrego Desert State Park into a gigantic blanket of wildflowers. Super Bloom 2017 was filmed over the course of several camping trips in a five week period from March - April.
PLEASE WATCH FULLSCREEN IN FULL HD WITH THE VOLUME UP!
For licensing & inquires email [email protected] All footage available in 4K.
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Music: "Count Of Tuscany" by Evgeny Teilor
Offroading in Anza Borrego State Park, east of San Diego, California
Imperial Sand Dunes - sand picked up by winds traveling over the Imperial Valley and then dropped when the wind runs into the mountains at the east side of the valley. I believe this area also hosted the Sarlacc pit in Return of the Jedi.
Mud volcano field on the edge of the Salton Sea California - the heat that feeds these actually comes from steps in the San Andreas fault system.
At this point, it seems that the whole internet has heard the story about how a swarm of earthquake activity near the Salton Sea in Imperial County, California, has raised the chances of a large earthquake on the San Andreas Fault, and an earthquake advisory was issued detailing all of this. If many headlines and reactions to them are to believed, the Big One is imminent, and large swathes of southern California are about to bite the big one.
So, how much of this is true? Do we need to worry?
Well, the raised probability aspect is, in fact, true - or it is according to our best understanding of how faults interact with each other. But we’re talking a raise to a maximum of a 1% chance in the next seven days. One percent! Or less! I don’t think I’ve ever seen a 1% chance of something bad happening get magnified into It Is Imminent And About To Happen, but that’s how this story is increasingly being spun. It’s misleading at best, and harmful at worst, when one major initial purpose of the earthquake advisory was simply to acknowledge that scientists are paying attention to what’s going on down there instead of just ignoring it.
Wait, but it did go up? How, then?
Faults are actually a lot like people. They undergo a lot of stress from day to day. For people, stress can come from a lot of things, but for faults, it mainly comes from the long-term motion of tectonic plates. People have a whole lot of different coping mechanisms to not break under the stress, but all faults share the same coping mechanism: friction. Just like you may have a breakdown when you can’t handle the stress in your life, faults break when the amount of stress they’ve accumulated is too much for friction to resist. That breaking process is an earthquake.
Most of the stress on a fault comes from plate motion, but other earthquakes on nearby faults can also add stress to the picture. The bigger the earthquake, the more stress it inflicts on everything around it. But, unlike stress accumulation from plate motions, the stress change from another earthquake is pretty instantaneous. It’s possible - and has happened - for an earthquake to set off another one within seconds, hours, or even a couple of days, but the longer you go since that earthquake, the more apparent it becomes that the stress change wasn’t enough to send any other faults into breakdown mode.
So - that increase in earthquake likelihood on the San Andreas, up to maybe as high as one percent last week, came from the stress changes from this earthquake swarm on top of the regular tectonic stresses. The odds are lowering again now that the swarm itself is slowing down.
But the bigger issue is - is that increase actually something to worry about?
I’d say not particularly, no, and I’m not alone among seismologists here.
Firstly - there are lots of swarms like this near the Salton Sea. They happen a couple of times per decade, and they tend to last for a few days. Swarms in this area in 2008 and 2012 had earthquakes with magnitudes in the low 5s; the largest one this time around has been a 4.3. These earthquakes all occur on faults that are not the San Andreas, and so far, there is zero historic precedent for one of these swarms directly preceding earthquake on the San Andreas, or any other fault. All of these swarms also raised stresses on the San Andreas, raised the odds of a larger quake to something like what they were last weak, just without a formal earthquake advisory issued - and nothing happened. This is enough precedent that, basically, if there IS a Big One soon, it was very close to happening anyway regardless of the current swarm. It’s entirely possible that a swarm event could eventually be the proverbial straw that broke the camel’s back, but there just isn’t enough energy involved in one of these swarms to bring the fault from Not Particularly Close to Big One. It won’t be the cause in and of itself.
Secondly - earthquakes that aren’t parts of swarms also affect stresses on nearby faults. The larger the earthquake, the more substantial the stress change, and the longer the period of increased hazard. Things like the 1992 M7.3 Landers or the 2010 M7.2 El Mayor Cucapah earthquakes kicked the San Andreas a lot harder than this week’s swarm of 4s did, but that didn’t set it off, either. If a similar earthquake advisories has been published after those, the percentages would’ve looked scarier than 1%. Earthquake scientists were actually pretty worried after Landers and its M6.4 aftershock near the San Andreas in Big Bear, and that’s not the case right now. We’re observing, but nobody’s particularly worried. Basically, faults affect each other all the time, it’s just that those effects are usually not the immediate triggering of another large earthquake.
Thirdly - the southern San Andreas is considered the highest hazard fault in the state already, but we’ve been living with it that way for a long time. The last earthquake on the part of the San Andreas was sometime in the late 1600s, and the average time between earthquakes on that section of the fault is more like 200 to 250 years. This is a section scientists have been saying is due for a while, which is what brings on the extra attention when there’s a swarm, and the extra nervousness. The most recent USGS statistical earthquake forecast - based on everything we know about every fault in the state - puts the odds of a M6.7 or greater on the southern San Andreas Fault at 19% within the next 30 years and the odds of a M7.5 or greater at 17.3%. That’s the baseline we’re living with, and this swarm hasn’t changed it by very much or for very long. And for another southern California point of comparison, your odds of getting into an accident on a Los Angeles freeway in any given year are higher than the yearly odds of a San Andreas earthquake, let alone your odds of being hurt in that earthquake.
So then…why issue a statement at all?
This kind of thing shows that scientists acknowledge the swarm, acknowledge it’s in an area that has already had media attention for being high hazard, and acknowledge that people are nervous. (Which, hooboy, the advisory did fail as an effective acknowledgment of nerves, looking at the reaction it’s caused.) It’s also some insurance against anyone who can claim later that “nobody said anything about the risk” if this becomes the unprecedented case where the swarm does lead to a damaging earthquake. That was the case with a swarm in central Italy in 2009 which eventually lead to a M6.4. The L’Aquila earthquake killed a bunch of people, and the scientists involved ended up on trial for manslaughter for ostensibly not acknowledging the change in risk. The whole L’Aquila situation was a huge mess of bad communication and bad policy, and that part of Italy didn’t have the precedent of lots of swarms without a bigger quake like the Imperial Valley does, but hey. It happened. We want to avoid that here in California.
Another important goal of advisories like that is to remind people, yes we’re on an active plate boundary and we have earthquakes. Yes, preparedness kits are a good idea. A lot of folks seem to misread “check your emergency kit” as “you’re gonna need it really soon” though, which is…a problem that may be hard to work around. But if you can’t use small earthquakes as a motivator to prepare for big ones, that’s a problem, too. If people are only motivated to prepare in hindsight after getting wrecked by a large earthquake, that’s not an effective mitigation strategy. I absolutely always tell people to use small ones as a reminder to prepare for big ones, but media storms like this are just a sign that scientists need to watch our phrasing, too…
I have been meaning to reblog this since it appeared over the weekend. At least I remembered tonight. Share widely - seismologist commenting on the recent “Earthquake alerts” in California
The Creeping Imperial Fault
Southeast of the Los Angeles basin and due East from San Diego lies California’s Imperial Valley. It is heavily irrigated, as you see from the small irrigation ditch featured in this photo. The land is quite flat and has been filled in with sediment from the Colorado River. Thanks to irrigation channels leading from the Colorado, the area has become a rich area for growing plants and vegetables.
But, many unseen geological features lurk beneath the surface of the Imperial Valley. The San Andreas Fault enters the northwestern tip of this Valley, but then breaks off into a couple different segments along the coastline of the Salton Sea. South of the Salton Sea, the fault reorganizes into a system that travels into Mexico known as the Imperial Fault.
In this photo of what appears to be a simple Imperial Valley irrigation ditch, you’ll notice that the concrete has cracked and there are plants growing through the concrete along these fractures.
This irrigation ditch sits directly atop of the Imperial Fault. This picture was taken from the “North American” plate side of the fault, looking across at the Pacific plate, so the land to the top of this image is moving to the right relative to the viewer (the San Andreas system being a right-lateral fault).
The fault hasn’t had a major earthquake since a magnitude 6.4 event in 1979, which happened before this channel was built, but it’s still there and still slowly creeping. Concrete doesn’t handle shear stress very well, so here it’s cracking due to that slow motion. The Fault hasn’t had large motions since 1979, but it still creeps along, allowing very subtle motions to take place while the stress builds up that will eventually drive a larger earthquake.
This fault also offsets a nearby rail line and telephone poles, some of which were built before the 1979 quake and are offset by a meter or more. There is also, for some reason, a buried high pressure gas line at this location.
-JBB
Image credit: Me, image owned by the author of this post.
1979 Earthquake details: http://www.data.scec.org/significant/imperial.html
Never got around to sharing some pictures from my geology trip to the Imperial Dunes a few weeks ago. The Imperial Dunes are the largest (spatial extent wise) sand dunes in North America! Also, the San Andreas fault runs very close along here, so there’s a lot of thermal energy build up that manifests as mud volcanoes. They’re still very active, and they smell like fresh asphalt. Also we stopped by the Salton Sea and it was very sad.
