HOLLISTER (CBS SF) -- A swarm of seven small earthquakes hit the Bay Area Wednesday evening, according to the U.S. Geological Survey's automated seismograph alert network.
The quakes ranging from magnitude 0.4 to 1.6 struck shortly before 8 p.m. Pacific Time at an estimated depth of 5km below the earth's surface. Deeper quakes are less noticeable while a shallow quake--in the 0 to 40 mile depth range--can feel much stronger than their actual reported magnitude. Quakes just below the earth's surface, in the 0 to 10 miles range, can cause even more damage at lower magnitudes.
The quakes hit from the Hollister area in the south to as far north as Napa.
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Strong earthquakes with an epicenter off the coast can trigger tsunamis, depending on the size and type of the fault movement. The Pacific Tsunami Warning Center tracks earthquake data for the West Coast.
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