The Trembling Earth

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Tag Archives: earthquake

On my way to SSA

This week I’m attending the Seismological Society of America annual meeting in Salt Lake City, Utah. The society was founded in the wake of the 1906 San Francisco earthquake, so the annual meetings generally coincide with the quake’s April 18 anniversary.

20130416-165449.jpg

Salt Lake City’s pioneer past is still evident overlooking the Wasatch front from the Utah State Capitol

This year’s conference is held in Salt Lake City, at the foot of the gorgeous and seismically ominous Wasatch Mountains. As such the conference is nominally focused on earthquake hazards in the U.S. intermountain west. The organizers have done a marvelous job arranging events, public lectures, and coordinating with Utah’s statewide ShakeOut drill on Wednesday in order to raise public awareness of the risks posed by the Wasatch Fault.

Below are details on the two big public events, if you’re in Utah and looking for some straight-from-the-source earthquake info. I’ll report more throughout and after the week on other goings-on at the conference, including the discussion and results from my own session on what stops earthquake ruptures, and a big field trip to see the Wasatch fault and SLC’s seismic preparedness on Saturday.

Public Events
The Great Utah ShakeOut
http://www.shakeout.org/utah/
Wednesday, April 17
10:15am
Everywhere – under a table!

Town Hall Meeting
http://www.seismosoc.org/meetings/2013/townhall.php
Wednesday, April 17
7:30-9:00pm
Downtown Radisson – Wasatch ballroom

Sunday Reading #3

Apologies for the tardiness. I suppose for some of you this is Sunday evening reading, if that’s what people even do on Sunday evenings. Maybe for those of you hunkering down in the U.S. midwest.

Here are two weeks’ worth of seismic tidbits I posted on Twitter, since the first week was a little dry. Catch up on all things quakey!

Overcompensating in L’Aquila
In oh-so-foreseeable news, Italian officials are now trigger-happy with evacuation orders in the wake of the manslaughter conviction of seismic hazard officials. Caution is good… but, this is why we have legends like the boy who cried wolf.

“Why evacuate for an earthquake no one can feel?”
http://www.bbc.co.uk/news/magazine-22039903

A nice antidote to that painful bit of news is a call to arms about the risky state of building design in such a quake-prone region:
http://www.csmonitor.com/World/Europe/2012/0521/Italy-earthquake-modern-buildings-not-ancient-ones-pose-biggest-threat-video

Man-made Earthquakes
The seismic hot-topic of the decade, human-induced earthquakes, gets a summary treatment by Popular Mechanics. The summary is good. You’ll be hearing more about this from me and all of us in the future:
http://www.popularmechanics.com/science/energy/coal-oil-gas/how-big-could-a-man-made-earthquake-get-15299728

“Rolling” versus “sharp” earthquakes, explained

“The Earthquake Machine”
How do you scale down faults so that you can understand their frictional and mechanical behavior in controlled tests? Popular Science has a neato infographic on the equipment used in rock mechanics tests–earthquake laboratories.
http://www.popsci.com/technology/article/2013-03/earthquake-machine

Earthquakes and Society
Christchurch residents and architectural pros alike balk at the rebuild designs for the downtown cathedral:
http://www.dezeen.com/2013/04/08/critics-back-restoration-of-earthquake-christchurch-cathedral/

Nepal introduces an emergency plan for a crucial post-quake lifeline, its airport:
http://www.irinnews.org/Report/97766/Priming-Nepal-s-airport-for-earthquake

Exposé of an ethically questionable but increasingly common industry–disaster tourism:
http://travel.nytimes.com/2013/04/07/travel/tourism-in-javas-land-of-ghosts.html

Animal earthquake predictors
There has been a modest buzz this week about research on a longstanding legend of seismic phenomena. Animals have occasionally been reported to appear to foretell earthquakes, but anecdotal evidence generally fails any rigorous scientific test, and most such observations are thus dismissed as unreliable indicators of any impending quake. Researchers in Germany, however, have begun to study ants that live in colonies along fault lines. Surprising finding: their level of activity changes from a daily average before small tremors. I wouldn’t make too much of this yet, but I think it’s really cool to finally see some potential for scientific tests of a long-standing, intractable myth/puzzle about quake phenomena. Now if only we could fill all our fault lines with German Redwood ants…. I wonder if they distinguish between magnitude 2 and magnitude 7…

The news release:
http://www.ouramazingplanet.com/4360-ants-sense-earthquakes.html

The researchers’ website:
http://www.uni-due.de/geology/research/ants_earthquakes.shtml

Landslide in Utah Copper Mine

Quarry collapse at the Bingham Copper Mine, Utah

Quarry collapse at the Bingham Copper Mine, Utah

A noteworthily massive collapse occurred this week at a quarry outside of Salt Lake City, Utah. The event is outside of my scientific jurisdiction, but Dave Petley has been covering it with great interest, and has reported a bit about the seismic signature of this mighty landslide:
http://blogs.agu.org/landslideblog/2013/04/12/the-unusually-large-bingham-canyon-mine-landslide-an-impressive-example-of-prediction-using-monitoring/

Honshu quake

DYFI130413Honshu

A modest but substantial 5.8 tremor rattled the southern Japanese island of Honshu this week, doing a fair bit of damage on Awaji island and the densely populated area surrounding it. A collection of videos record the shaking from a few urban cameras, the second of which demonstrates the noise created by a rattling city:

YouTube user KOJI PEI posted a video showing a real-time (actually ~2 or 3x speed) animation of shaking intensity at each of Japan’s seismometers during this quake. I’m not sure where this video came from nor how specifically it was generated (it appears to be maximum acceleration averaged over a several second time window), but I’m hoping to find out and to find more like it. You can see seismic waves radiate outward from the epicenter, with the relatively gentle P-waves leading the charge, and swishy S-waves ringing outward behind them.

Seismic engineering – For your Office, Museum, or Bedroom!
Scaled down base isolators can secure servers, lab apparati, antiques etc. on specialized tables.
http://gizmodo.com/5994528/watch-this-anti+earthquake-table-shrug-off-a-violent-simulated-tremor 

The principle of base isolation is already successfully applied in buildings around the world, and this mini-version may be hugely popular with companies and museums whose equipement and specimens need to be seismically protected. One of the commenters also has some insightful things to add, including the major deficiencies in maximum displacement and vertical protection.

Big news on a big move this week – I’ll update you all shortly!

Sunday Reading #2

Here’s the second installment of my now weekly series in which I compile all the neat-o earthquake things I’ve relayed via Twitter over the prior week.

National Tsunami Week

From March 24-30, the U.S. National Oceanic and Atmospheric Administration (NOAA) and Federal Emergency Management Agency (FEMA) teamed up to raise awareness of tsunami hazard, assembling a huge number of resources. Get informed about the tsunami risk to your coast line, and learn what you should do–I compiled their compilations here.

Earthquake Anniversaries

There were some notable earthquake anniversaries this past week: in 1983 a hefty jolt shook Portland–the “Spring Break quake.” In 1964, the largest earthquake in North America’s modern history, the M9.2 Good Friday earthquake, shook Anchorage for several minutes, jostling loose all kinds of landslides and faults, and sent a massive tsunami racing across the Pacific.

Fluid Injection & Induced Earthquakes

A paper was published this week documenting the striking correlation between the timing/location of damaging earthquakes and the timing/location of industrial fluid injection. Oklahoma has this problem, Arkansas has this problem, and the Netherlands has this problem.
http://geology.gsapubs.org/content/early/2013/03/26/G34045.1.short
Ooops.

Turkey’s Urban Renewal/Quake Retrofitting Plan Kicks In

Earlier this year, the government of Turkey initiated an urban renewal project in Istanbul that will replace deadly apartment blocks with housing built to withstand their inevitable temblor(s).
www.invest.gov.tr
– info from Turkey’s gov’t
Earthquake Hazard for Istanbul – blog article summarizing the policy

Some are not as happy as others about this:
http://www.theatlantic.com/international/archive/2013/03/preparing-for-earthquakes-istanbul-rattles-its-apartment-dwellers/274410/

Seismic Engineering (failures)

The new eastern (Oakland) span of the San Francisco-Oakland Bay Bridge may have had a bit of a setback this week when dozens of enormous bolts used in its seismic joints failed during seismic testing. Ooops. They’ll be fixed/replaced… but the grand opening may be pushed back. :(
http://www.nydailynews.com/news/national/bay-bridge-quake-safety-bolts-fail-test-article-1.1300679

Earthquake Footage

YouTube’s “EarthquakeVideoMex” compiled a few new videos of earthquake footage, one from a M6.3 in Mexico a few years ago (with some amazing standing waves in an upper story pool):

…and one from the M6.5 that jolted Taiwan earlier this week.

Earthquakes and Cheese

In potentially the most important earthquake-related development of the week, we learned how the Parmagiano-Reggiano industry recovered from a devastating earthquake that struck almost a year ago and wrecked millions of dollars worth of cheese.
The Miracle After Italy’s ‘Parmesan Quake’ – WorldCrunch news

See you next week! Or hopefully before then. Happy reading. Join in the fun and get these in real time @TTremblingEarth on Twitter!

National Tsunami Awareness Week – March 24-30, 2013

The Great Wave by Hokusai

This week the United States has been recognizing National Tsunami Week, an awareness campaign by NOAA, the USGS, FEMA, and a whole host of other emergency response agencies to ensure that the American public is aware of the tsunami hazard facing our coasts, and that we know what to do about it.

The bottom line is that we face threats on all fronts, although they’re greatest along the Pacific shore. Local megaquakes in the Pacific Northwest will one day wash torrents of water ashore in Washington, Oregon, and Northern California. More frequently than that (we have two examples from this decade alone), giant quakes elsewhere around the Pacific will send tsunamis racing across the ocean to flood our shorelines and swirl around our harbors. Large quakes in the Caribbean and landslides out in the Atlantic pose a tsunami threat to our Gulf and Atlantic coasts.

Fortunately we’re familiar with this risk because we’ve seen the effects of even 1-meter-high tsunamis on our coastline:

NOAA maintains several tsunami warning centers (including Pacific and West Coast/Alaska), and we’re ever striving to improve our detection capabilities as well as inform the public.

Take the opportunity to inform yourself this week, and “be Tsunami Ready!”   There are tons of resources, listed below.

Tsunami Awareness Week from the National Tsunami Hazard Mitigation Program:
http://nthmp.tsunami.gov/taw/tsunami-awareness-week.html

What to do to protect yourself:
http://www.tsunamiready.noaa.gov/

Tons of tsunami resources from California
http://www.calema.ca.gov/NewsandMedia/Pages/Current%20News%20and%20Events/National%20Tsunami%20Preparedness%20Week.aspx

USGS report on “Community Exposure to Tsunami Hazards” [pdf document]
http://pubs.usgs.gov/sir/2012/5222/sir2012-5222.pdf

NOAA’s Center for Tsunami Research has a ton of cool models and animations (their YouTube channel is chock full, at YouTube.com/noaapmel) that represent the best measurements and calculations from actual tsunami events that have happened. One recently released model shows the best estimate of what happened during the Good Friday earthquake of 1964 in Alaska. The tsunami from that quake ravaged the U.S. coastline in Alaska, Hawaii, Washington, Oregon, and California and caused fatalities. Get informed! These things happen.

Sunday Reading

This is the inaugural post of a weekly series I promised to start that will supplement my more in depth but sporadic blogging about topical seismic events. A couple months ago I joined Twitter to broadcast some of the interesting seismic news snippets I come across daily, including lots of content that didn’t really warrant drawn out posts. As I promised then, I’m now compiling my full week of Tweeted links into a “weekend reading” sort of post, to let you catch up on all the earthquake news you missed as it flew by on Twitter. So here goes: a bunch of articles about earthquakes to read, and why to read them.

Earthquake Early Warning

The biggest U.S. quake news was the tremor that rattled L.A. a couple weeks ago and spawned renewed lamentations about the stagnant state of California’s earthquake early warning system. The New York Times had the most comprehensive story:
http://www.nytimes.com/2013/03/21/us/california-lags-behind-on-a-quake-warning-system.html

…but some local media outlets had their own lamentations to add:
http://sfist.com/2013/03/22/cas_earthquake_alert_system_is_basi.php

To me the highlight of the New York Times piece was the imaginative explanation of what benefits early warning of an earthquake could provide:

“[Japan’s EEW system was able to] activate computerized programs to slow commuter trains so they did not go off their tracks, stop elevators so passengers were not stranded between floors, flash highway warning signs instructing motorists to slow down and avoid overpasses, and open doors at fire stations so they would not be stuck shut should power be lost.
The warning would go out to home computers and personal cellphones, giving surgeons a moment to withdraw scalpels, workers at Disneyland time to shut down Space Mountain, home cooks an opportunity to turn off the gas and everyone a moment to… dive under a desk.
If you are cooking, you can step away from the boiling water… it would help people psychologically, decreasing the surprise that can freeze people in confusion and fear when the ground starts moving, or lead to panicked and dangerous reactions, like running outside a building.”

I like the introduction of the intangible psychological benefits of reducing the paralyzing suddenness with which earthquakes set upon us.

Emergency Kits

A bunch of articles have just come out regarding earthquake survival kits.

Oregon Live asks where to put them (the answer is “everywhere… and make sure they’re accessible”).
http://www.oregonlive.com/living/index.ssf/2013/03/earthquake_preparation_where_t.html

The USA Today introduces us to some particularly dedicated preppers:
http://www.usatoday.com/story/news/nation/2013/03/23/oregon-earthquake-survivalists/1996555/

And the New Zealand Herald describes an effect I think most seismologists would be ecstatic to learn of: small tremors have a huge impact on emergency kit sales (up 300%), signaling that people really do treat the benign moderate jolts as reminders of real hazard.
http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10873205

Prediction vs. Mitigation

On a subject intimately related to the prior two, The Guardian published an article by Dave Petley, director of the Institute of Hazard, Risk, and Resilience at the University of Durham (and perhaps known more familiarly as the author of AGU’s Landslide Blog). Dave presents the elusive ideal of earthquake prediction through a simple and plainspoken set of thought exercises, which ultimately illustrate that prediction isn’t truly what we want. Mitigation, preparation, and a few moments warning should suffice… and may have to.
http://www.guardian.co.uk/science/blog/2012/may/30/attempts-predict-earthquakes-harm-good

Tsunamis Galore

On the 2nd anniversary of the March 11, 2011 M9.0 Tohoku earthquake, the National Oceanic and Atmospheric Administration reminded us that twenty eight other tsunamis have struck various parts of the world since then.
http://www.nnvl.noaa.gov/MediaDetail2.php?MediaID=1304&MediaTypeID=1

Earthquakes Rock the Atmosphere

A widely circulated research result this past week was the discovery of significant signals from the Tohoku earthquake… recorded by satellite gravity measurements as pressure waves passed through the edge of the atmosphere. There’s a great animation of the data here:
http://spaceinvideos.esa.int/Videos/2013/03/Earthquake_felt_in_Space

That should do it for now. Tune in again next weekend, or Follow me on Twitter! @TTremblingEarth

When an unremarkable quake becomes remarkable

>9,000 southern Californians reported feeling Monday morning's temblor

>9,000 southern Californians reported feeling Monday morning’s temblor

On Monday morning this week, a wide swath of southern California–from L.A. to Needles to Calexico–was gently jolted by a modest M4.7 earthquake from the San Jacinto fault.

On most of the planet this quake would have been unremarkable, but having shaken a population exceeding 7 million people, it earned some remarks. In fact, in the 24 hour period surrounding this earthquake there were 27 of similar or larger magnitude around the world, but this one earned the attention. (That link will probably update with time… if you need convincing you can just set up a “custom data feed” for March 11, 2013.)

The screen grab below shows all M4+ earthquakes that occurred on March 11, 2013. Most of these went unnoticed. Some were felt by many, but didn’t receive the (U.S.) coverage of the SoCal tremor.

M4+ on March 11, 2013

I love seeing the bimodal reactions of southern Californians to an earthquake of this size. No doubt the unnerving sensation of the ground suddenly shuddering beneath you is frightening to many, but there seem to be just as many who could scarcely care less.

Watch as it disrupts (or doesn’t) the coverage of the nearby Indian Wells BNP Paribas Open tennis tournament:

Southern California news media pounced on it, looking for any harrowing story of alarm or toppled tchotchkes, but came up predictably empty handed given the light and fleeting nature of the shaking. One of the big stories was that this tremor served as a further successful natural test run of California’s nacent Early Warning system, thus far only shared among a handful of scientists while it awaits further successful tests without alarming the public.

The other interesting facet of the quake was the initial determination of its location and magnitude, which was ironically marred by having a sizeable precursory foreshock, a sizable and immediate aftershock, and great instrumental sensitivity/coverage. At the outset, seismic waves from the foreshock and aftershock, which were separated from the mainshock by 16 and 51 seconds, respectively, tricked the automated system into mislocating the source and origin time of shaking. Initially the USGS identified three earthquakes with magnitudes ranging from 4.7-5.1 that occurred within two minutes of each other. Of course to most of the populace that distinction in the wavetrain would have scarcely been discernable. It was moot anyway, because as the system and seismologists further processed additional data the true sequence of events became clear. A 2.3… 16 seconds… a 4.7… 51 seconds… a 3.0. Meanwhile the shaking from each of those was rippling outward through the L.A. region and desert, overlapping with each other in their rattling. This confusion is an interesting artifact of having a great, quickly responsive seismic network… that’s not quite dense enough to pick out the details of everything it detects right away.

Southern California’s dense seismic network allows detection of minuscule earthquakes, so there is a rich foreshock and aftershock sequence evident surrounding the mainshock hypocenter. Viewing the list of foreshocks makes me intensely curious about the nucleation process of larger earthquakes.

Foreshocks and aftershocks in the 2 days before and after Monday's quake

Foreshocks and aftershocks in the 2 days before and after Monday’s quake

The L.A. Times has a good informative piece about the quake and its regional significance as expressed by USGS scientists:

Magnitude 4.7 earthquake is Monday morning’s shake-up call – L.A. Times

By the way, “Shake-Up Call” is totally in.

February: What a month to miss!

I have finally returned and settled back into life in a quiet NorCal college town after living for a month in the bustle of Beijing, where I conducted four weeks of lab work for my dissertation project.

State Key Lab

I spent my time there working with and in the lab of colleagues at the China Earthquake Administration, a collaboration that I’ll describe in more detail in a later post. Stuck on the other side of the Great Firewall from Facebook, Twitter, and even WordPress, I missed a great deal of the global online fun during some major Earth-shaking events that happened during February. It killed me deep inside, though I had my own great time in Beijing.

I may break these events down into individual posts if I manage the time, but for now I’ll leave you with a cursory summary:

The month began with a monstrous earthquake in the South Pacific, the culmination of weeks of foreshocks in an area that has seen a years-long sequence of large and fascinating ruptures. The M8.0 quake produced a local tsunami that wiped out some villages, and was followed (and continues to be) by hundreds of sizable aftershocks. One of the most interesting aspects of earthquakes is the complex way in which fault ruptures unfold–in both space and time–and the Solomon-Vanuatu Trench has undergone a marvelous sequence.

The next big news was an “earthquake” in North Korea. The Earth did indeed quake, with the strength of a 5.1, but the seismic waves were generated by a huge atomic explosion, not the volume-preserving double-couple of tectonic slip. The CTBTO detected this detonation immediately on instruments worldwide, and, decidedly unconcerned with hiding this from anybody, North Korea quickly proclaimed their third successful nuclear bomb test.

The next rare and global seismic event was not Earth-derived at all: a surprisingly large and exceedingly rare meteor strike rocked the countryside of central Russia, and BOY was it ever captured on film. Thank goodness (or insanity, actually) for Russian dash-cams.

Who knew a meteor sounded like that?? They’ll have to remake Deep Impact. The shockwave from this extremely supersonic space rock was large enough to buffet pressure gauges on the other side of the planet, and the shockwave’s interaction with the ground excited seismic waves that also spread through the planet.

While I was in China, the south of the country had a strange spate of moderate earthquakes, at least one of which proved a successful test of their new Early Warning System. In rural parts of that country many buildings cannot withstand the shaking of even a magnitude 5 earthquake, so these were a bigger deal than they might otherwise have been given the size.

Other seismological things are happening–Christchurch is debating retrofits, for example–so I’ll just have to keep you posted. Glad to be back; you can finally expect more posts in the future!

Yakko, Wakko, and Dot recount the Northridge quake

“It’s just the planet moving granite several city blocks.”

Our favorite cat/monkey/dogs reflect on their experience of L.A.’s 1994 temblor. Of course the Warner Brothers studios–where the writers work and the Animaniacs themselves live–is situated in the heart of Burbank, where shaking from the Northridge earthquake (on January 17, 1994, at 4:30 in the morning) was severe. In the early 90s L.A. truly established itself as the city of disaster by heaping mudslides upon fires upon riots upon disastrous quakes. But heck… we’re Californians.

…and just for all our records, and because they’re just so clever, here are the lyrics:

Animaniacs – A Quake! A Quake!

This is the city: Los Angeles, California

On a starlit winter night
When the moon was shining bright
Back in January of 1994 …
At 4:30 in the morning
And without a single warning
Something strange began to move the floor.

A quake! A quake!
The house begins to shake!
You’re bouncing ‘cross the floor and watching all your dishes break.

You’re sleeping, there’s a quake;
You’re instantly awake!
You’re leaping out of bed and shouting, “Oh for Heaven’s sake!”

I ran outside with neighbors
Their faces filled with shock
That’s because I’m standing there in NOTHING BUT MY SOCKS!

Oh a quake, a quake,
Say it’s all a big mistake!
Just feel the ground go up and down / Won’t someone hit the brake?

A quake, a quake!
Oh what a mess they make!
The bricks, the walls, the chimney falls / destruction in its wake.

I did not have insurance
So I called them from the scene
And suddenly I’m list’ning to an answering machine /
Say, ‘too late, too late!
You shouldn’t ought’a wait,
‘Cuz now you’re stuck, we wish you luck, here comes a six point eight.’

Whose fault? Whose fault?
The San Andreas’ fault.
Cuz Mister Richter can’t predict her / kicking our ass fault!

Seismologists all say tectonic plates are in between
An encroaching crust and mantle,
Yeah so what the heck’s that mean?!

It means a quake! A quake!
Oh really, yeah, no fake?
We kind of had that feeling when the ground began to shake….

California’s great!
It’s such a lovely state.
And every lawn is sitting on a continental plate.

Los Angeles had fires
And a riot and a flood
And then a drought and a recession and then now we hear this thud
Of a quake, a quake
How much more can we take?
We thought that we had seen it all but this one takes the cake.
The dirt. The rocks.
And all those aftershocks.
It’s just the planet moving granite several city blocks.

L.A. town is falling down
while the ground / moves around
We won’t let us get it down
We’re Californians.

A quake, a quake.
It’s time to pull up stake.
We’re all fed up we can’t deny it
Fires, quakes, and floods, and riots,
We want some place with peace and quieeeeeet…

So we’re moving to Beirut!

Remembering Northridge

Today is a day of significant quake anniversaries for the U.S. and Japan.

The last U.S. quake to kill more than a few people struck the L.A. suburb of Northridge 19 years ago today, in the wee hours of the morning. The San Fernando Valley was hit hard, but the whole L.A. area rattled violently, and seismic waves from The Valley were focused through the Santa Monica Mountains into the populous west side, an effect that’s apparent in the “Did-You-Feel-It” map if you’re familiar with the geography of L.A (click there for info if you aren’t. Or for fun if you are).

DYFINorthridge

Damage was widespread and many of the area’s freeways shut down for months after major collapses when their concrete supports failed during the strong shaking. Despite the huge monetary cost (right between hurricanes Andrew and Katrina… and potentially behind Sandy) and moderate death toll, this was not Los Angeles’ “big one.” In the scheme of possible So Cal earthquakes, this was a relatively small one, and rather than hitting the core of the city, it struck a glancing blow by starting in the suburbs and sending most of its energy northward into the mountains. Nonetheless it is Angelenos’ clearest reminder (although its age must have erased it largely from modern relevance) of what to expect when a significant quake strikes the city.

Exactly a year later a quake of nearly the same magnitude struck a much more densely populated corner of the planet: Kobe, Japan. This quake, almost identical in magnitude to CA’s Northridge earthquake of the year before, is the source of that quintessential earthquake footage most everyone will be familiar with:

The Kobe quake’s death toll was two orders of magnitude higher than Northridge’s, and the damage to the port city was devastating, largely because of widespread liquefaction, an effect that was much less prevalent in the coarse sedimentary basins of Mediterranean L.A.

As we mark this anniversary of those significant earthquakes, as usual you should take advantage of this heightened awareness to double-check that you’d be ready were a similar quake to happen today. Let the commemoration serve to remind you that these were real events that really happened, and could happen again at any moment.

An iconic photo of 90s L.A.

An iconic photo of 90s L.A.

Join my SSA special session: When and Why do Earthquake Ruptures Stop?

The clock is ticking on abstract submission for the April 17-19 annual meeting of the Seismological Society of America. Julian Lozos (of Seismogenic, and of course of the PhD program at UC Riverside) and I are convening one of the special sessions, entitled “When and Why Do Earthquake Ruptures Stop? Evaluating Competing Mechanisms of Rupture Termination.”

I highly encourage any of you who think you have answers to that question to submit an abstract for a poster or talk in our session.

The detailed request is below, but I’ll emphasize here that this question is near and dear to my heart as essentially the broad topic of my PhD dissertation research. I can describe that in a future post, but if you want to hear the deets, come to our session!

I should also emphasize that the deadline is seriously rapidly approaching: Thursday, January 10 at 5pm Pacific (UTC -8)!   Eek!

SSA 2013 Special Session:

When and Why do Earthquake Ruptures Stop? Evaluating Competing Mechanisms of Rupture Termination

Summary:

Cessation of coseismic fault rupture has been suggested to result from a variety of mechanisms, ranging from fault-specific static properties to transient, rupture-history-driven dynamic effects. Field and modeling evidence alike implicate static or quasi-static properties such as fault geometry, frictional asperities or regions of creep, and time-dependent poro-elasticity as strong controls on rupture endpoints. However, static, dynamic, and quasi-dynamic numerical models, as well as mounting instrumental and field evidence demonstrate that, as stress evolves over multiple seismic cycles, transient effects may periodically overcome established static barriers, allowing rupture to continue. While much work has been done to investigate the effects of individual mechanisms on rupture cessation, the next step is to merge disparate studies of competing mechanisms in order to understand their relative roles within a given fault system. We invite presentations that summarize findings from numerical models, laboratory tests, observational analyses, and field and paleoseismic investigations that address various mechanisms that inhibit earthquake ruptures. We encourage comparison of these effects with one another, as well as discussion of how to evaluate which properties may dominate rupture through a given fault system, and of how to determine which effects are persistent over multiple earthquake cycles.

Conveners:

Austin Elliott (University of California Davis, ajelliott@ucdavis.edu)

Julian Lozos (University of California Riverside, jlozo001@student.ucr.edu)

See you in Salt Lake City!

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