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19 February 2018

78 seconds of Earthquake Early Warning

Late on Friday afternoon, February 16, during the Chinese New Year street fair in la Ciudad de México, the tight hold between the North America and Cocos plates failed, the fault slipped, and the Pacific coast of Oaxaca lurched around a meter out toward the ocean. Within six seconds, the profound ripple this let loose through the crust heaved the Huazolotitlán seismic recording station westward as well, followed shortly by …

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11 April 2017

Who feels earthquakes?

Earthquakes are felt by people somewhere on the globe just about hourly (see this USGS list of felt earthquakes in just the last 24 hours). Some places are particularly prone to them–think Japan, Indonesia, Chile, Italy, California–while some stable parts of the continents will go generations, or even millennia, without anyone there feeling any quaking of the ground. But even in, say, California, where “felt” earthquakes occur daily, most individuals go months …

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16 November 2016

Complex, compound New Zealand earthquake – Part 1: Seismology by Night

Just after midnight last Sunday, the whole country of New Zealand was rocked by a massive earthquake at the north end of the South Island. From the outset, this earthquake was more confounding than most, and as more reports and data amass, we’re gaining a picture of a complicated earthquake that stemmed from the failure of several large faults in succession. These successive failures may have resulted from structural linkages …

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24 September 2015

Chile keeps having earthquakes

…and keeps surviving them barely scathed. Chile has this year been rocked by its 3rd Great earthquake this century–its 14th if you include the last. Though the earthquake’s magnitude and the resulting Pacific-wide tsunami earned it headlines, it was a very mild earthquake in the global scheme of seismic impacts. This has a bit to do with the nature of offshore, subduction zone earthquakes, and a LOT to do with …

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29 May 2015

Views of strong shaking in Nepal and what they teach us

When the ground shook throughout Nepal in April, it was neither predicted nor surprising–the paradox of inevitable but chaotic large earthquakes within well known seismic zones. Though warnings of Nepal’s catasrophic earthquake risk have been sounded for years, and though this magnitude 7.8 and its energetic 7.3 aftershock wrought plenty of death, destruction, and tragedy, scientists are finding themselves somewhat surprised at the apparently rather limited degree of overall damage …

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17 April 2015

Tearing through California Part 1: the Central San Andreas

On display in central and northern California is the rare and troublesome phenomenon that’s the mischievous cousin to sudden, wrenching earthquakes: slow, steady fault creep. Rather than remaining pressed firmly together until they lurch past each other in violent earthquakes, the two sides of a creeping fault glide gradually along, generally silently carrying along everything above them. The good news is that this process takes up strain that would otherwise be …

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11 September 2014

Lurching ground and bouncing bridges in the Napa earthquake

My rides along Amtrak California’s Capitol Corridor now include an eerie stretch where they pass the site at which the highest ground motions in the Napa earthquake were recorded mere weeks ago. Just at the south abutments of the I-80 bridges over the Carquinez Strait, where the Union Pacific tracks pass through the C&H refinery, a shallow borehole seismometer recorded an acceleration of 0.99g, nearly the full force of gravity lurching soil and …

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30 August 2014

Earthquake rupture through a U.S. suburb

In the quiet wee hours of a NorCal summer night, the ground lurched beneath the mud of the northern San Francisco Bay and sent seismic waves roaring upward and outward into the world-famous wine valley’s central city, Napa, CA. After they wreaked their havoc in Napa and nearby communities the seismic waves spread farther afield and gently rumbled most of the Bay Area and its exurbs from our weekend slumber. By the time …

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2 April 2014

Monstrous earthquake in Chile… as it unfolds

The northern coast of Chile has been struck by a Great earthquake this evening, shaking the South America continent for hundreds of miles and thrusting a tsunami onshore and across the Pacific Ocean. Notably, this earthquake occurred in a well known seismic gap, the sole reach of South America’s Pacific coast subduction zone that did not rupture in the 20th (or 21st) century. In that sense, this was one of …

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18 February 2014

How hard has your zip code shaken?

Did you feel it? …Ever? These USGS maps show the highest shaking intensity reported in every zip code throughout the U.S. (and cities of the world) in the past two decades. 1991 – 2012  The USGS’s crowd-sourced Community Internet Intensity Maps, popularly known as “Did-You-Feel-It” maps, have been collecting online surveys of seismic shaking intensity since 1997. There’ve been plenty of quakes in that time, and in 2012 researchers put together …

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5 February 2014

Stunning HD videos show volcanoes erupting … gorgeously

As the Tectonic Plates bend, creak, snap, and rattle in earthquakes, blobs of heated rock rise through them from within and punch through the surface, puffing out vast clouds of rock dust and volatile gas, and pouring out mounds upon mounds of hardening molten rock. Volcanoes may fall under the purview of some other realms of the blogosphere, but a spate of recent videos are just too stunning (and informative!) …

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21 October 2013

Watch the whole U.S. ripple

Want to see what happens to the ground in the United States when an earthquake snaps the crust elsewhere in the world? The waves ripple outward through the continent oscillating each county and city in turn. This video shows real data from seismometers deployed across the country. Each dot represents a seismometer. Each instrument’s motion is displayed here as alternating red (for upward motion) and blue (for downward motion). Individually …

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2 October 2013

The creative forces of earthquakes

For all the destruction wrought when human settlements and infrastructure are shaken by tectonic forces, earthquakes are the result of processes that create and rejuvenate the landscapes we live in. In late September, 2013, a mighty earthquake ripped through the Pakistani desert, causing a surprisingly small number of casualties, but nonetheless rendering homeless over 100,000 people, a major swath of nearby mountain villages’ populations. In the vicinity of the epicenter …

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2 August 2013

The jiggling Earth, or, what are all those squiggles?

Ever since we first formally recorded one more or less a century and a score ago, the seismogram of an earthquake has become an iconic symbol. Oversimplified and unrealistic ones abound, but natural seismograms of earthquakes are distinctly identifiable. Despite the unique details of every earthquake, seismograms around the world are phenomenally similar. The differences among them are actually what allow seismologists to understand the propagation of earthquakes and the structure …

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2 June 2013

Danse de la Terre

Last week marked 100 years since the debut of my favorite piece of music of all time: Igor Stravinsky’s Rite of Spring. The ballet debuted to a legendary amount of controversy, but its cacophonous, haunting beauty has been recreated and rechoreographed countless times in the past century, including for example this 1975 Pina Bausch version of the culminating “Sacrificial Dance,” which I’m pretty certain forms the main inspiration for the 1983 Thriller …

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10 May 2013

Wasatch! Part 2 – Protecting the capital’s Capitol

After seeing the terrorizing evidence of the Wasatch Fault snaking its way through mountainfront Salt Lake City, our 2013 SSA field trip headed to the newly retrofit Utah State Capitol to see how the state is dealing with the looming threat of earthquakes. Reaveley Engineers’ Jerod Johnson, one of the head structural engineers on the retrofit project, led us on an in-depth tour of the facility, explaining all of the …

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21 November 2012

Amazing liquefaction in Tokyo

A new video from Japan [embedded below] shows liquefaction occurring at a scale and scope that I haven’t seen before in video footage. The video is from Urayasu  town, Chiba Prefecture–an industrial suburb of Tokyo that appears to be sited on made land adjacent to Tokyo Bay. No wonder it sloshes so heavily: made land (fill) is particularly susceptible to liquefaction. We just can’t pack things down the way nature can …

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31 March 2012

Mexico City Earthquake Early Warning–it works!

Want to see what happens when you can know an earthquake is coming? Mexico has footage that’s got you covered. Update 6 April 2012: They also have an app that alerts you to earthquakes before they hit… in Mexico City. (También tiene una App que se alerta de sismos antes de tiembla!) On March 20, 2012 a very large earthquake rocked southern Mexico. With a magnitude of 7.4 and a …

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5 May 2011

Swaying high-rises and resonance frequencies

In a post a few weeks ago I linked to a humbling video of high-rise buildings in Tokyo swaying after the 9.0 quake. Well, those buildings were full of tens of thousands of people, plenty of whom had cameras. That video was only the beginning; below are many more that capture the dramatic oscillation of the towering steel edifices. The swaying is especially clear in the following video, likely filmed …

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22 April 2011

Earthquake early warning in action

No country would have been better prepared for such a massive earthquake than Japan. Straddling the boundaries between four converging tectonic plates, Japan is one of the most earthquake prone nations in the world, and is probably the most earthquake savvy. They have world-class networks of monitoring instruments including seismometers, tide gauges, and GPS locating stations; they routinely practice for massive quakes, which they are often visited by; and they …

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