Last night, shortly after 8 pm, there was an earthquake near San Jose. I’d just made it home after a particularly ugly BART delay, due to an apparent suicide at Powell Street station around 6 pm:

BART’s Powell Street station in San Francisco was reopened just before 8 p.m. tonight after authories shut it down for two hours to investigate a death on the tracks.

Up in San Francisco, the quake was fairly mild. I mistook the shaking for vehicles on the street at first, until I realized there was no noise and the shaking was continuing for much longer than I expected.

I was the first to fill out the shaking report from my ZIP code in San Francisco. (At the time I write this, there are now almost 250 reports.) Magnitude is an important measurement of earthquakes, but the Mercalli intensity scale is a more useful answer to the “how did it feel?” question. In the USGS map, brighter colors (yellow/orange/red) correspond to higher intensities:

October 30, 2007 quake intensity map (cropped)
(Click through for a full map with the color code.)

Most of the Bay Area reported intensity III (“Slight”), described as: “Felt quite noticeably by persons indoors, especially on the upper floors of buildings. Many do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated.” In other words, it’s only slightly more than a non-event. Pay no attention to the breathless media news briefs squeezed into the gaps between TV shows.

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