Strong Earthquake north of San Francisco BayIn the early hours this morning, a magnitude 6 earthquak
Strong Earthquake north of San Francisco BayIn the early hours this morning, a magnitude 6 earthquake struck in the area of Napa Valley, California. The exact earthquake strength estimates will likely be refined throughout the day as data is processed, but this is the largest earthquake to strike the Bay Area since the 1989 Loma Prieta quake.The quake struck near a fault that produced a damaging magnitude 5 quake a little over a decade ago and in the area near the West Napa Fault and the Rodgers fault, but it reportedly took place on a different strand of one of those faults. The USGS is currently working to identify exactly which fault broke in this quake.The damage to the area will be significant, although hopefully the loss of life will be minimal. The type of geology in this area exerts a strong control on how intense the shaking is; the earthquake took place in a valley likely filled with loosely-packed sediment, a setup that tends to intensify shaking. Those sediments are separated from the rocks that make the nearby hills and so there is less energy transferred to those areas. If you look at this USGS Shakemap, you can see this effect quite clearly – the valley itself got a strong shake, but the intensity drops in the higher ground. Napa and surrounding cities sit within these valleys, so there is likely to be heavy damage to older or unreinforced brick buildings. It’s night right now, but early images seem to confirm that.When there is an earthquake like this, big enough to do damage but not catastrophic, it’s a good time to remember earthquake preparation. In the event of a quake, get yourself under a strong table and get outside once it is over. Have a preparedness kit ready. Know how to get in touch with your family members – text messages are often the best these days because they don’t tie up phone lines. And perhaps the biggest from my perspective; have a supply of fresh water available for your family; when a large quake happens, that is the one item everyone needs and if the water-transport infrastructure is damaged, it’s the one item no one will have.-JBBImage credit:http://earthquake.usgs.gov/earthquakes/eventpage/nc72282711#shakemapRead more:http://www.decodedscience.com/m6-1-earthquake-napa-valley-shakes-san-francisco-24-august-2014/48886http://abcnews.go.com/US/northern-california-struck-60-magnitude-earthquake/story?id=25101008http://t.co/yrcblCdW1H -- source link
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