California’s Two Recent Earthquakes Erupted on Unknown Fault Lines

My geophysicist friend tells me that the two big Ridgecrest earthquakes last week happened along fault lines we didn’t even know existed. Here’s a map of all the aftershocks from the two quakes:

The shorter set of aftershocks outlines the area of the 6.4 earthquake. The longer set outlines the 7.1 earthquake. The purple lines show all the previously mapped fault segments in the area. One of those is a potential problem:

My worry is that both of these fault segments were not mapped before, and both lie close to a long fault that ruptured historically. The Garlock Fault lies at the lower right of the figure, trending WSW-ENE, and it produced a 7.5 quake in 1952. For the last few days the folks at the USGS have probably been estimating how many bars of stress have been gained or lost on the Garlock as a result of the quakes that SoCal experienced last week. Although rock stresses are typically measured in kilobars, history tells us that 1-2 bars of additional stress can trigger the next quake. A 7.5 quake would be 0.4 Richter units larger than the Friday quake, roughly 4x larger in energy release. But also along a longer fault that crosses some major highways. I would be concerned for at least the next 12 months.

And that is your earthquake news for the day.

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SIX TRUTHS

Reclaiming power from those who abuse it often starts with telling the truth. And in "This Is How Authoritarians Get Defeated," MoJo's Monika Bauerlein unpacks six truths to remember during the homestretch of an election where democracy, truth, and decency are on the line.

Truth #1: The chaos is the point.

Truth #2: Team Reality is bigger than it seems.

Truth #3: Facebook owns this.

Truth #4: When we go to work, we're in the fight.

Truth #5: It's about minority rule.

Truth #6: The only thing that can save us is…us.

Please take a moment to see how all these truths add up, because what happens in the weeks and months ahead will reverberate for at least a generation and we better be prepared.

And if you think journalism like Mother Jones'—that calls it like it is, that will never acquiesce to power, that looks where others don't—can help guide us through this historic, high-stakes moment, and you're able to right now, please help us reach our $350,000 goal by October 31 with a donation today. It's all hands on deck for democracy.

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