GEOGRAPHY

The magnitude 6.0 earthquake that struck California’s Napa Valley north of San Francisco on Sunday morning—collapsing older buildings, sparking fires and causing scores of injuries—fell along a series of cracks in the Earth tied to the famed and feared San Andreas Fault. (National Geographic News)

Take a look at this map to see the web of faults beneath the San Francisco Bay Area.

(For a full summary of the South Napa Quake, download this typically terrific poster from the good folks at the USGS.)

Discussion Ideas

• The so-called “South Napa Quake” had its epicenter near Browns Valley California. (The quake was named for the county in which Browns Valley is located, Napa.) Use our MapMaker Interactive to identify the region and mark it using the drawing tools on the left-hand side. Here is a map of the Bay Area to get you started.
  • Zoom in on the town of Napa, just north of the giant San Francisco Bay. Browns Valley is just west of Napa.

• The National Geographic News article was written before the USGS identified the fault responsible for the South Napa Quake. Take a look at this nice map identifying some major faults in the San Francisco Bay Area. Using your MapMaker Interactive map identifying Browns Valley, which fault do you think is most likely to responsible for the quake?
  • The USGS says it was the West Napa fault, although some geologists identify the source as the nearby Rodgers Creek fault.

• Take a look at the USGS map of faults slicing through the San Francisco Bay Area. (Either above or on our website here.) Using the Wikimedia map above, see how many faults you can label.
  • If nothing else, you should be able to clearly identify the area’s two major fault regions: the Hayward fault zone, to the east of the bay, and the mighty San Andreas, to the west.

Current Event Connection is back from summer hiatus! Hurrah!