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April 11, 2017

Who feels earthquakes?

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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November 16, 2016

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

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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September 24, 2015

Chile keeps having earthquakes

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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May 29, 2015

Views of strong shaking in Nepal and what they teach us

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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April 17, 2015

Tearing through California Part 1: the Central San Andreas

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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September 11, 2014

Lurching ground and bouncing bridges in the Napa earthquake

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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August 30, 2014

Earthquake rupture through a U.S. suburb

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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April 2, 2014

Monstrous earthquake in Chile… as it unfolds

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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February 18, 2014

How hard has your zip code shaken?

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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February 5, 2014

Stunning HD videos show volcanoes erupting … gorgeously

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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