Napa Earthquake which fault is at fault? 
Monday, August 25, 2014, 01:57 PM
Posted by Snow Bunny
The early morning earthquake, whose epicenter was about 9 miles south of Napa, jolted residents and had winemakers scrambling to check their homes and businesses.

This is the busiest time of year because of the harvest is on. The whites have started, and reds are coming soon in two to six weeks. A lot of people come to Napa for September and October because it is harvest and enjoy he festivities.

While the San Andreas Fault is a specific fault line, it's also the collective name for a 70-kilometer wide shear zone of individual cracks and faults along the boundary between the two plates. The entire fault system is nearly 1,300 kilometers long, and extends at least 15 kilometers deep into the crust.



The diagram shows the major faults within the Greater Bay Area. Image credit: USGS

Within the Bay Area, the main San Andreas Fault cuts through San Francisco and sections off Point Reyes. Many other faults within the zone are also prominent and active enough to earn names — the Hayward Fault shows up in real estate paperwork, and Rogers Creek shares a name with a Vineyard. Many of these faults, like San Joaquin and Green Valley, are the structural underpinnings of the long valleys .characteristic to the region. There are many more faults that don’t even have names yet.

Today's earthquake was between a pair of active fault systems, the Hayward-Rodgers Creek Fault system and the Concord-Green Valley Fault system. The epicenter is near the West Napa Fault, which has ruptured sometime in the past 11,000 years, and the Carneros-Franklin Faults, which haven't ruptured in longer.

We don't know the fault this earthquake ruptured on at the moment but there is some speculation that the San Andreas may have been involved at some level or it could be a blind fault (one covered with sediments and with no recent movement) that we didn't know about until today.

In either case the Napa quake rattled nerves and caused damage and sent over 100 people to the hospital. Just a reminder yet again that California is on the move and we all need to be prepared.

As for Mammoth Lakes no reported damage and it appears that the San Andreas was the sleeping giant in the Sierra’s.

http://mammoth395.com/
#mammoth395 #sanandreas #napaearthquake


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