seismology

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Thingvellir National Park in Iceland is where the Vikings held their parliament meetings and the subsequent Icelandic government continued to use the sight to convene their general assembly from 930 to 1798. It’s also where the Eurasian and North-American tectonic plates meet, hence the huge fissure which is the result of earthquakes and seismic movement.

When tectonic plates collide, sometimes one plate sinks, or subducts, below another one. This can trigger an earthquake. When earthquakes cause the ocean floor to move, the water moves, too. Columns of water travel across the ocean and grow taller as they approach land, becoming a tsunami.

Scientists use computer models to predict whether a tsunami will occur. The model can forecast the wave’s speed, direction, and height as it approaches land. Local authorities can then warn communities that might be in danger.

Learn more about earthquakes and tsunamis.

Inge Lehmann [1888 - 1993]

Inge Lehmann was a Danish Seismologist who discovered the Earth’s inner core. In 1936 she postulated from existing seismic data that the Earth’s core is not a single molten sphere, but that an inner core exists, which has physical properties that are different from those in the outer core. This conclusion was quickly accepted by seismologists, who up to this time had not been able to propose a workable hypothesis for the observation that the P-wave created by earthquakes slowed down when it reached certain areas of the inner Earth.

Happy Birthday Inge Lehmann, Discoverer of Earth's Inner Core

In 1929 a large earthquake occurred near New Zealand. Danish seismologist Inge Lehmann “the only Danish seismologist,” as she once referred to herself—studied the shock waves and was puzzled by what she saw. A few P-waves, which should have been deflected by the core, were in fact recorded at seismic stations. 

Lehmann theorized that these waves had traveled some distance into the core and then bounced off some kind of boundary. Her interpretation of this data was the foundation of a 1936 paper in which she theorized that Earth’s center consisted of two parts: a solid inner core surrounded by a liquid outer core, separated by what has come to be called the Lehmann Discontinuity. Lehmann’s hypothesis was confirmed in 1970 when more sensitive seismographs detected waves deflecting off this solid core.

Born in Denmark in 1888, Lehmann was a pioneer among women and scientists. Her early education was at a progressive school where boys and girls were treated exactly alike. This was a sharp contrast to the mathematical and scientific community she later encountered, about which she once protested to her nephew, Niles Groes, “You should know how many incompetent men I had to compete with—in vain.” Groes recalls, “I remember Inge one Sunday in her beloved garden…with a big table filled with cardboard oatmeal boxes. In the boxes were cardboard cards with information on earthquakes…all over the world. This was before computer processing was available, but the system was the same. With her cardboard cards and her oatmeal boxes, Inge registered the velocity of propagation of the earthquakes to all parts of the globe. By means of this information, she deduced new theories of the inner parts of the Earth.”

A critical and independent thinker, Lehmann subsequently established herself as an authority on the structure of the upper mantle. She conducted extensive research in other countries, benefiting from an increased global interest in seismology for the surveillance of clandestine nuclear explosions. When Lehmann received the William Bowie medal in 1971, the highest honor of the American Geophysical Union, she was described as “the master of a black art for which no amount of computerizing is likely to be a complete substitute.” Lehmann lived to be 105.

Learn more about Lehmann and experience the power of earthquakes in the exhibition Nature’s Fury: The Science of Natural Disasters, now on view. 

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Don’t be shaken – Lucy’s not leaving us

Even as the dust was still settling with our nerves still quaking, for many of us in Los Angeles, one woman seemed to have all the answers. That was Lucy Jones, the doctor on-call when the earthquakes strike. 

Some have called her the Beyoncé of earthquakes. Well, she just announced she’s retiring from the U.S. Geological Survey. (But don’t panic. She’s not leaving California behind.)

There’s been a lot of love for Lucy on Twitter. One response I got asked the question many of us have: “Who else will come out in her bathrobe in the middle of the night to say it probably was not a precursor?”

As reporter Rosanna Xia put it: In her 33 years with the USGS, Jones has become a universal mother for rattled Southern Californians. After each quake, she turns fear of the unknown into something understandable.

While most of the earthquake guys aren’t remembered, Dr. Jones is certainly unforgettable to many of us who grew up in Southern California. In addition to making something complicated understandable (and a little less scary), she also helped to dramatically change the way we prepare for earthquakes across Southern California. 


“When the big one hits, people will be living because of the work that she has done." 

– Los Angeles Mayor Eric Garcetti  


What’s next for her? Helping to develop science-based policies on climate change. 

What’s next for us? Wondering who will be the one to settle our nerves with information when we are still quaking after the inevitable next temblor.  


You can read more about Dr. Lucy Jones and her work here. 

@mmaltaisla 


Photos by Los Angeles Times

Earthquake Playlist

I am a seismologist with a musical background, and as such, I’ve been compiling as many songs about earthquakes as I can possibly find for the past several years. My criteria for a song to make this list are either that it actually really truly be about earthquakes, or that there be fairly extensive earthquake-related imagery or metaphor. Name-checking specific events or faults gets more points than just saying the word “earthquake” once, even if the song isn’t directly about anything seismic (ie. “Wayward to Hayward” is an instrumental, “Neal’s Fandango” is a pre-1989 song that still mentions Loma Prieta peak a whole lot). The shorter subset playlists I’ve made out of this longer set tend to also include things like “All Shook Up,” “Shakin’ All Over,” “Shake Rattle and Roll,” or “I Feel the Earth Move.” I don’t include those on this list because branching out to include songs that sound seismic in context would be daunting, especially since I am not including every single song I’ve found that actually mentions the word “earthquake” once and only once.

Here is my list as it stands now, in alphabetical order by title. Despite there being many titles in common, each and every one of these is a unique song. None are covers. (Yes, I was surprised to find so many songs called “Loma Prieta”!)

A Quake! A Quake! - The Animaniacs
Another Earthquake - Aaron Carter
The Ballad of San Andreas - Julie Felix
The Burning of Frisco Town - 1906 period song
California - Belinda Carlisle
California Earthquake - Cass Elliott
California Earthquake - Norman Greenbaum
California Earthquake Song - Danney Ball
The California Shake - Margot Guryan
Day After Day (It’s Slippin’ Away) - Shango
Earthquake - Alicia Healey
Earthquake - Fortunate Youth
Earthquake - Little Boots
Earthquake - Sarah Cheevers
The Earthquake - High Country
The Earthquake Came At Dawn - 1906 period song
The Earthquake Of Your Love - Al Kooper
Earthquake Rumble - Bill Nye the Science Guy
Earthquake Song - The Little Girls
Earthquake Song - Ventilator
Earthquake Weather - Beck
End of the World - REM (or Great Big Sea)
La Falla de San Andrés - Kevin Johansen
Getting Through To Her - 311
The Great Alaska Earthquake of 1964 - Bob Blake
Livin’ on the Fault Line - The Doobie Brothers
Loma Prieta - Amy Cook
Loma Prieta - Liz Pappademas
Loma Prieta - Matt the Electrician
Natural Disaster - Muse
Neal’s Fandango - The Doobie Brothers
New Madrid - Uncle Tupelo
Of Pressure - Mirah
Phoenix and the Faultline - The Plastic Constellations
The Quake of ‘89 - Kathy Kallick
Richter Scale - Kent Clark, Elliot Davis, and the Caltech Stock Company
San Andreas - Meg Hutchinson
San Andreas - Steve Gollnick
San Andreas Fault - Anique Granger
San Andreas Fault - Bazza
San Andreas Fault - Lu Watters and the Yerba Buena Jazz Band
San Andreas Fault - Natalie Merchant
San Andreas Fault - The Sundowners
San Andreas Fault - Top Of The Fair
San Francisco, Our Beloved -1906 period song
The Santa Barbara Earthquake - Green Bailey
Shakin’ Shakin’ Shakes - Los Lobos
Sin City - Uncle Tupelo
Southern California Wants To Be Western New York - Dar Williams
Wayward to Hayward - Ricky Skaggs
Why Does This Always Happen To Me - Weird Al Yankovic
Wrecking Ball - Gillian Welch

Any glaring omissions? Any suggestions for expanding this list to an even more insufferable magnitude?

IT JUST HAPPENED AGAIN. SITTING IN BED. NOT STUDYING FOR MY SEISMOLOGY MIDTERM TOMORROW! EARTHQUAKE HAPPENS! HOLY SHIT ILL STUDY IM SORRY IM SORRY IM SORRY

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“It was six-legged, I know that; its skin was slaty gray that mottled to dark brown in places. Those brown patches reminded me absurdly of the liver spots on Mrs. Carmody’s hands. Its skin was deeply wrinkled and grooved, and clinging to it were scores, hundreds, of those pinkish "bugs” with the stalk-eyes. I don’t know how big it actually was, but it passed directly over us. One of its gray, wrinkled legs smashed down right beside my window, and Mrs. Reppler said later she could not see the underside of its body, although she craned her neck up to look. She saw only two Cyclopean legs going up and up into the mist like living towers until they were lost to sight.

“For the moment it was over the Scout I had an impression of something so big that it might have made a blue whale look the size of a trout - in other words, something so big that it defied the imagination. Then it was gone, sending a seismological series of thuds back. it left tracks in the cement of the interstate, tracks so deep I could not see the bottoms. Each single track was nearly big enough to drop the Scout into.” - Stephen King, The Mist

daziy  asked:

Love the Ichor group au. Poseidon I'm pretty sure owns dozens of cruise ships, does he do anything else? Also I imagine Hades as actually a member of the group but the public doesn't know him because he's a crime lord

no matter how hard I try I can never remember all the main gods in one go -_- lmao ok ay 

  • Poseidon is a shipping magnate, so anything ship related he’s into: war ships, cruise ships, shipping freights, etc. He also owns several prominent horse ranches and funds seismology research. Plus he marries Amphitrite before he knows Sally is pregnant with Percy, because he’s had his eye on the fishing business Amphitrite is set to inherit. 
  • Hades is in the jewel business (and has faced some blood diamond controversy) as well as owning over half of the world’s remaining coal mines. I imagine people think he’s a crime lord cause he has this cool demeanor  about him and is hardly ever in the public eye (they go out when Persephone really really wants to) but really it’s Persephone whose business dealings can be less than savory though Hades is more than happy to take the heat for his Queen. 

Since 2009, earthquake activity has increased throughout the central United States, specifically in areas employing new and emerging oil and gas production technologies. Join Dr. Justin Rubinstein, deputy chief of the Induced Seismicity Project at the United States Geological Survey, as he discusses this new breed of human-caused earthquakes.

This lecture took place at the Museum on November 10, 2016.

The Annual IRIS/SSA Lecture Series is presented in collaboration with the Incorporated Research Institutions for Seismology and the Seismological Society of America.

Made with SoundCloud

also. I’m a liar. I’ve decided Luvai and Kudrae are related, so Luvai is going to be part of the ever-expanding Nalix clan.

Luvai is the older sister, Kudrae the younger. their mother provided protection for a moisture farm on Tatooine and their father was…kind of a science guy. loved seismology and studied it extensively, but it didn’t really have much use on a moisture farm.

Luvai followed their mother around pretty much all the time. she wanted to learn how to defend herself, street-smarts, things like that. Kudrae and her father were probably closer just because Kudrae was a lot less prone to get into trouble, plus she was a thinker, even when she was small.

Luvai and Kudrae’s father was killed out in the Dune Sea by pirates who’d claimed part of the area as their territory. Luvai and Kudrae’s mother, in response, picked up and left the moisture farm, moving the family to Mos Anek, where her daughters might be better protected.

it was around this time Luvai and Kudrae’s mother was contacted by the Republic and offered a kind of…independent mercenary deal. she wouldn’t really officially join their ranks, but she’d serve as a kind of commando. she’d be leading strike teams on dangerous but profitable missions.

so their mom goes and fights on a few missions during the war, and so far things are going okay–their mom transfers credits into the family’s shared accounts, Kudrae kept accounting records, Luvai kept curious townsfolk from snooping around their business.

then on one of those dangerous missions, Luvai and Kudrae’s mom gets killed, so naturally her deal with the Republic is off. the credits they earned at first didn’t last long, and Luvai convinced Kudrae that if they got off-world, they’d have better opportunities. by now Luvai is 15, Kudrae 9.

they end up going to Corellia, and manage to eke out an occasionally nefarious living on the city’s streets for a few years. it was where Luvai got her start smuggling, and Kudrae wasn’t really comfortable with it, but it wasn’t like they had a lot of options, as Luvai put it.

one of Luvai’s smuggling jobs lands her in hot water with a Jedi passing through the city, and when Kudrae came to her sister’s rescue (well…as best she could, she was still a kid, after all) the Jedi promptly sensed Kudrae’s dormant Force-sensitivity. Kudrae was whisked away for Jedi training, and Luvai ended up on Corellia alone.

basically, Luvai ended up working for several gangs on Corellia, working her way up to being trusted with a ship, and as soon as they trusted her enough to give her a ship, Luvai cut ties, rewrote the ship’s registry to transfer ownership to her own name, and ditched them.

when the treaty of Coruscant was signed, Luvai was 17, Kudrae 11. when their class stories begin, Luvai is 27, Kudrae 21.

Candy wrapper core

That’s the title of a paper published in Scientific Reports this last week. The lead author, Maurizo Mattesini, a geophysicist from Madrid, proposes a new model for the make-up of Earth’s inner core. The paper title is captivating, but its explanation for the core’s structure is complicated.

The inner core is known to be formed of crystalline iron, but the exact atomic arrangement of the iron is uncertain, and remains an enigmatic puzzle in the most inaccessible part of our planet.

Keep reading

Father of Seismology

中文版

Shay spent his last years in Dublin, Ireland, his motherland.

This comic shares three headcanons with my other Rogue stories:

1, Shay occupied the Precursor Box, the manuscript and one of the powersources of Grand Temple.[Come Back To Me]

2,Shay is the founder of the Initiates.[Once upon a time in Italia]

3, In game Shay met and saved Rachel Plourde under a lighthouse in St.Anthony, North Atlantic. They loved each other in my fan comic.[Come Back To Me]

Time to play Syndicate!

So, about that earthquake advisory...

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…