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You are browsing the archive for August 2011 - Mountain Beltway.

31 August 2011

Columns form perpendicular to cooling fronts

This morning, Dana asks about the pattern of columns in this image: She muses: If I had a time machine and surviving-fresh-lava gear, I’d head back to see what this bugger was up to. Why did some of its columns form ramrod-straight whilst others are practically horizontal, or curved? I’d imagine it was contending with some ice round the edges, maybe some water, that caused it to cool all funny. …

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30 August 2011

Updated aftershock plot

The USGS reports more aftershocks, so your humble graphing servant has responded with a plot that updates the images I showed you last week. Here you go: Embiggable, via a simple click. Again, the “decay” pattern jumps out at us. One thing that I’m also noticing is how there are no events below 2.0 magnitude. What’s up with that? Simply not detectable? …or not worth bothering with? By the way, …

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28 August 2011

Damage to the Ecuadorian Embassy

My wife Lily is an Ecuadorian citizen. She was born in Quito, and we have traveled there together. (She’s also a U.S. citizen.) After the big earthquake on Tuesday, significant structural damage was reported at several Washington landmarks including the Washington Monument and the Smithsonian Castle. Another one, less recognizable to most folks, but key in our personal geography, is the Embassy of Ecuador. Not only is it an outpost …

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27 August 2011

Animated GIF of Virginia quake aftershocks

So last Tuesday we had an earthquake, and we expected some aftershocks as the crust in the Mineral, Virginia, area adjusted to the new stress regime. We expected those aftershocks to be lesser in magnitude, and to take place after the main shock. In other words, we would predict the following: And, indeed, over the past several days, that’s actually what happened:

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Friday fold addendum

Lee Allison, State Geologist of Arizona and exemplar of public outreach via blogging, sent me an e-mail yesterday regarding that awesome coastal Greenland shot by Alistair Knock that I featured as the Friday fold. Lee, like many of you, found the image entrancing and intriguing, and as he explored the unannotated version, he made some discoveries. In this e-mail, Lee pointed out a few more faults that I hadn’t noticed. …

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Why those curves, Rock Creek?

On Tuesday morning, before the earthquake hit, I answered an e-mail about DC faults. I get unsolicited e-mails all the time (and occasionally phone calls, too). The contact comes from people who have a geological question, find my blog, and figure that I might be willing to answer it for them, or to direct them to someone more knowledgeable. Sometimes they ask me to identify a rock. I see answering …

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26 August 2011

Friday fold: epic Greenland coast

The Friday fold is a beautiful straight-limbed antiform from coastal Greenland, courtesy of photographer Alistair Knock. Check it out and see if you can find anything that Callan didn’t annotate.

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25 August 2011

Aftershocks

Since Tuesday’s big earthquake, we’ve had 5* aftershocks in the same area (and possibly on the same fault). The most recent one popped off last night at 1am. Here’s a plot showing the size of the events (moment magnitude) relative to the passing of time: Note that the quakes that came after “the big one” are smaller in their size (the amount of energy that they release into the surrounding …

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24 August 2011

Cracking up

Callan shares a geological analogue that developed in his house yesterday: en echelon tension fractures, common in sheared rocks, appeared on his ceiling due to the Mineral, Virginia earthquake.

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23 August 2011

The Mineral, VA earthquake of August 23, 2011 – UPDATED

Callan describes his experience with the widely-felt east coast earthquake of August 23, and provides an analysis of the fault(s) that may be reponsible.

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