Vox - Napa earthquake of 2014https://cdn.vox-cdn.com/community_logos/52517/voxv.png2014-08-26T14:20:02-04:00http://www.vox.com/rss/stream/58293982014-08-26T14:20:02-04:002014-08-26T14:20:02-04:00Watch what an earthquake does in China vs the US
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<p>California's Bay Area experienced its strongest earthquake in decades this week, when a 6.0-magnitude earthquake hit Napa County. Over 100 people have been treated for injuries, but no deaths were reported. Earthquakes are much, much more deadly in other parts of the world. Earlier this month, a 6.1-magnitude earthquake killed hundreds in Southwestern China. The video above explains why.</p>
<p>Produced by Joss Fong and Joe Posner<br>Images courtesy of Getty, AFP, and China Foto Press</p>
https://www.vox.com/2014/8/26/6069921/watch-what-a-6-magnitude-earthquake-does-in-china-vs-the-usJoss Fong2014-08-25T09:50:02-04:002014-08-25T09:50:02-04:00Watch yesterday's earthquake wake everybody up
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<figcaption>(Photo by Justin Sullivan/Getty Images)</figcaption>
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<p>Yesterday's <a href="http://www.vox.com/2014/8/24/6062257/earthquake-san-francisco-bay-area-napa" target="_blank">early morning earthquake</a> in Napa Valley was detected by thousands of seismometers placed throughout Northern California and beyond.</p>
<p>But because we live in the era of the <a style="line-height: 1.5;" href="http://en.wikipedia.org/wiki/Quantified_Self" target="_blank">quantified self</a>, a network of other devices also picked up some interesting data on the quake: the thousands of <a style="line-height: 1.5;" href="https://jawbone.com/up" target="_blank">Jawbone wristbands</a> worn by people throughout the area.</p>
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<p class="caption">The percentage of Jawbone users woken up by the earthquake in various areas. (<a href="https://jawbone.com/blog/napa-earthquake-effect-on-sleep/">Jawbone</a>)</p>
<p>This chart, <a href="https://jawbone.com/blog/napa-earthquake-effect-on-sleep/" target="_blank">made by Jawbone</a>, shows the percentage of people asleep in various parts of Northern California during the night. The devices <a target="_blank" href="https://exist.io/blog/post/fitness-tracker-sleep/">can detect whether a user is asleep</a> based on accelerometer data.</p>
<p>Jawbone reports that in the towns of <span>Napa, Sonoma, Vallejo, and Fairfield — all less than 15 miles from the quake's epicenter — 93 percent of users woke up from the shaking. A bit further away, in San Francisco and Oakland, only about half of people woke up, and down in Modesto and Santa Cruz, almost nobody did.</span></p>
https://www.vox.com/xpress/2014/8/25/6065311/earthquake-bay-area-napa-sleepingJoseph Stromberg2014-08-24T19:10:02-04:002014-08-24T19:10:02-04:00Map: Comparing the 2014 and 1989 Bay area quakes
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<p><span>The earthquake </span><a href="http://www.vox.com/2014/8/24/6062257/earthquake-san-francisco-bay-area-napa" style="line-height: 1.5; background-color: #ffffff;">that rattled</a><span> Napa Valley and other parts of northern California on Sunday measured 6.0 on the magnitude scale. That was strong enough to damage buildings, injure 87 people, and leave thousands without power.</span></p>
<p>It was also the biggest quake in the Bay Area since the <a href="http://en.wikipedia.org/wiki/1989_Loma_Prieta_earthquake">Loma Prieta earthquake in 1989</a> that wreaked havoc in Santa Cruz, San Francisco, and Oakland. <i>That</i> one measured 6.9 on the magnitude scale and caused far more destruction — killing 63 people and injuring 3,757.</p>
<p>So how did the two earthquakes compare in terms of actual shaking on the ground? The map below, <a style="line-height: 1.5; background-color: #ffffff;" href="https://twitter.com/sumnerd/status/503588099683651584">put together</a> by UC Davis geologist Dawn Sumner, shows the difference. The 1989 earthquake (on the right) had <i>much </i>more violent shaking throughout the region:</p>
<p><b>The 2014 Napa quake (magnitude 6.0) vs the 1989 Loma Prieta quake (magnitude 6.9)</b></p>
<p><a href="http://cdn3.vox-cdn.com/uploads/chorus_asset/file/667464/2014_quake_vs_1989_quake.0.png"><img src="http://cdn3.vox-cdn.com/uploads/chorus_asset/file/667464/2014_quake_vs_1989_quake.0.png" class="small" alt="2014 quake vs 1989 quake"></a></p>
<p class="caption">Click to enlarge. Credit: <a href="https://twitter.com/sumnerd/status/503588099683651584">Dawn Sumner</a>, using data from the <a href="http://www.cisn.org/shakemap/nc/shake/72282711/intensity.html">California Integrated Seismic Network</a></p>
<p>It's worth remembering that <a href="http://en.wikipedia.org/wiki/Moment_magnitude_scale">the scale</a> that geologists use to measure the size of the energy released by an earthquake is logarithmic. That means that a magnitude 6.9 earthquake releases roughly <i>22 times</i> as much energy as a magnitude 6.0 earthquake.</p>
<p><span>That said, the amount of ground shaking that actually occurs depends </span><a style="line-height: 1.5; background-color: #ffffff;" href="http://earthquake.usgs.gov/research/shakemap/">on a variety of additional factors</a><span> besides magnitude — the depth at which the earthquake takes place, how far away the quake is, the type of rock and soil in the region, as well as how the seismic waves propagate through the Earth's crust.</span></p>
<h3>Further reading:</h3>
<p><span>David Perlman of the </span><i style="line-height: 1.5;">San Francisco Chronicle </i><a style="line-height: 1.5; background-color: #ffffff;" href="http://www.sfgate.com/bayarea/article/Bay-Area-quake-struck-on-long-dormant-fault-USGS-5708819.php#page-2">has a good rundown</a><span> of what geologists know so far about the 2014 Napa earthquake. The quake appears to have occurred along the West Napa Fault, a </span><a href="http://www.data.scec.org/Module/sec1pg16.html">right-lateral strike slip fault</a><span>. (Strike slip faults are common in California — in an earthquake, the blocks on either side of the fault slip horizontally past each other.)</span></p>
<p><span>By contrast, the 1989 Loma Prieta quake occurred further south — likely on an offshoot of the San Andreas Fault. Here's </span><a href="http://earthquake.usgs.gov/regional/nca/1989/">a rundown</a><span> from the US Geological Survey of that earthquake, which involved not just horizontal slipping along the fault but also some possible </span><a href="http://news.stanford.edu/pr/94/941011Arc4099.html">lifting and sinking</a><span>.</span></p>
<p>The AP <a style="line-height: 1.5;" href="http://www.santacruzsentinel.com/localnews/ci_26397900/how-big-was-napa-earthquake-heres-where-it?source=rss&utm_source=dlvr.it&utm_medium=twitter">offers</a><span> a helpful list of major earthquakes throughout California since 1989. And Roger Pielke Jr. of the University of Colorado </span><a href="http://rogerpielkejr.blogspot.com.au/2014/08/normalized-us-earthquake-damage.html">ranks</a><span> the most damaging quakes in the United States over the past century (when adjusted for inflation, population growth, etc., the 1906 earthquake in San Francisco tops the list).</span></p>
https://www.vox.com/2014/8/24/6063599/earthquake-california-napa-vs-loma-prietaBrad Plumer2014-08-24T09:10:02-04:002014-08-24T09:10:02-04:00A 6.0 magnitude earthquake just hit the Bay Area
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<figcaption>A building in Napa, California, damaged by the 6.0 magnitude earthquake. | (Photo by Justin Sullivan/Getty Images)</figcaption>
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<p>At 3:20 a.m. Pacific time on Sunday, an earthquake with a magnitude of 6.0 hit the San Francisco Bay Area.</p>
<p>The <a href="http://www.ncedc.org/recenteqs/QuakeAddons/NC72282711.html" target="_blank">USGS reports</a> that it occurred 6.7 miles below the surface, <span>with an epicenter just south of Napa and about 30 miles northeast of San Francisco. This is the strongest earthquake</span><span> felt by the region in 25 years, since the </span><a href="http://en.wikipedia.org/wiki/1989_Loma_Prieta_earthquake" target="_blank">1989 Loma Prieta quake</a><span>, which had</span><span> a magnitude of 6.9.</span></p>
<blockquote lang="en" class="twitter-tweet">
<p>Shake map of this morning's earthquake via the <a href="https://twitter.com/USGS">@USGS</a>. <a href="http://t.co/lafXiiIM3e">pic.twitter.com/lafXiiIM3e</a></p>
— SFGate.com (@SFGate) <a href="https://twitter.com/SFGate/statuses/503492331568242689">August 24, 2014</a>
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<p>There have been no deaths reported so far, but <a href="http://www.sfgate.com/bayarea/article/Northern-California-quake-Child-in-chimney-5708941.php" target="_blank">87 people are being treated for injuries</a> at a Napa hospital, and three are in critical condition — including a child struck by fragments of a collapsing chimney.</p>
<p>There are also numerous damaged buildings and roads in and around Napa, including <a href="http://www.usatoday.com/story/news/nation/2014/08/24/napa-valley-earthquake/14524035/" target="_blank">a damaged highway foundation</a> near the city of Vallejo.</p>
<p><img src="http://cdn1.vox-cdn.com/uploads/chorus_asset/file/667400/454076390.0.jpg" class="small" alt="napa court house"></p>
<p class="caption">The Napa County court house. (Photo by Justin Sullivan/Getty Images)</p>
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<p class="caption"><img src="http://cdn1.vox-cdn.com/uploads/chorus_asset/file/667402/454076412.0.jpg" class="small" alt="napa store"></p>
<p class="caption">A storefront in Napa. (Photo by Justin Sullivan/Getty Images)</p>
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<p class="caption"><img src="http://cdn2.vox-cdn.com/uploads/chorus_asset/file/667404/454076418.0.jpg" class="small" alt="napa car"></p>
<p class="caption">A car damaged by falling bricks. (Photo by Justin Sullivan/Getty Images)</p>
<p>Additionally, at least <a target="_blank" href="http://www.latimes.com/local/lanow/la-me-ln-quake-near-napa-jolts-bay-area-20140824-story.html">42,000 homes are without power</a> in the area. At 5:47 am, a magnitude 3.6 aftershock occurred, and the <a href="http://www.ncedc.org/recenteqs/QuakeAddons/NC72282711.html">USGS says</a><span> the probability of another aftershock is high, with a 54 percent chance of another strong quake in the area in the next week. It'll probably be weaker than this earthquake, but there's a 5 to 10 percent chance it could be equal in magnitude or stronger.</span></p>
<p>The earthquake is believed to have <a href="http://www.sfgate.com/bayarea/article/Bay-Area-quake-struck-on-long-dormant-fault-USGS-5708819.php" target="_blank">occurred along the West Napa Fault</a>, which runs parallel to a number of more frequently active faults, including the Rodgers and San Andreas. <span>Over time, as the Pacific Plate slides past the North American Plate, energy builds up along these faults and is occasionally released during earthquake events.</span></p>
<blockquote class="twitter-tweet" lang="en">
<p>Here is a geologic map of the north bay with the earthquake location (modified from Wagner et al., 2011) <a href="http://t.co/VXV2DswhwK">pic.twitter.com/VXV2DswhwK</a></p>
— Nick Swanson-Hysell (@polarwander) <a href="https://twitter.com/polarwander/statuses/503526724249059329">August 24, 2014</a>
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<p><b>Update</b>: This article has been edited to reflect ongoing developments.</p>
https://www.vox.com/2014/8/24/6062257/earthquake-san-francisco-bay-area-napaJoseph Stromberg