Earthquake blogging
8:08pm: I’m in San Francisco…I felt it…nothing fell off the shelves, but it got close…our cat freaked out a bit…don’t know any info yet…i’ll update later
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8:16pm: See shake map below…only 12 minutes after quake…right now, it’s a 5.5 according to initial reports…looks like the Hayward fault
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8:45pm: Okay…excitement over…I guess I’ll get back to work. It’s officially a 5.6 according to USGS (see here). See my superbly annotated GoogleEarth image below with epicenter near San Jose in the South Bay, and my location in SF.
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9:11pm: The very first reports were a little off, and I said it was the Hayward Fault, but I was wrong – it was on the adjacent Calaveras Fault (strike-slip fault). Here’s an updated map from this USGS site.
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9:48pm: What a great distraction from writing my thesis a moderate earthquake is! I was doing a little reading about the Calaveras fault system (here), and the researchers make this statement regarding forecasting:
We suggest that the 1984 Morgan Hill earthquake, Mw 6.2, is a reasonable maximum magnitude event to occur in these segments, so rather than apply a detailed segmentation model we chose to assume that such an event has an equal likelihood of occurring anywhere along the entire southern Calaveras fault.
Not too shabby…it was a 5.6.
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10:01pm: For as much time as I spend on my computer and the internet, I can’t believe I never heard of this. Twitter? Apparently, you sign up and then tell people what you are doing at that very moment. Right. Anyway…here’s a screenshot (from this Flickr page) showing the response to the quake. A lot quicker than the news wires, that’s for sure.
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The Next Day: The updated “Did You Feel It?” map is below. In the very first version of this map (top of post), there were 174 responses in only ~15 minutes. Now there are over 61,000 responses. This is one of those things where the value of a networked world is appreciated. Fantastic.
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Clastic Detritus 
Hi Brian,
nice real-time earthquake blogging!
First thought: cool blogging.
Second thought: now I want to see an estimate of the stress changes on the adjacent faults from a M 5.6 on the Calaveras Fault. I think the Hayward Fault would be in the quadrant that would be stabilized, but I’ve only just started reading papers on earthquake triggering and they haven’t filtered into my intuition yet.
Third thought: heh. The GSA Structure/Tectonics division meeting was going on during that earthquake… but in Denver. And there were a lot of grad students and post-docs who study seismogenic fault structures there, between two theme sessions on the subject and a symposium on the San Andreas. And they missed this earthquake.
Fourth thought: I wonder if the M5-ish earthquake during the summer before Loma Prieta changed the stresses enough to make Loma Prieta more likely?
Fifth thought: good luck finishing the dissertation!
Kim…your thoughts:
1: thanks (Alessia too)
2: I’ll leave that up to someone else to figure out
3: they did miss it, this was the strongest i’ve ever felt…just enough to remind me I live on a plate boundary, but not enough to wreak havoc
4: I don’t know if I like that thought, but perhaps
5: thanks
Ahh.. earthquake blogging, one of my specialties heh. Nice job Brian, good thing it was only 5.6. After the recent 8.0 earthquake in Peru I went into earthquake blogging mode, and it took me 10 days to get out of it. It was all worth it though, many people was thankful for the information. Sadly, most take interest about it after the disaster, but that’s another story.
Cheers.
Miguel…your coverage of that much bigger quake was really good…although I hope you don’t have to do it again very soon.