Wednesday, August 24, 2011

Shake Rock Rattle and Roll

I did not feel it. No matter what you have heard on the news, I am stating that it is categorically impossible for even the most sensitive person to have felt the Virginia earthquake in Chicago. Ohio, possibly. Chicago, no. Ground waves would have dissipated by the time it got to our area.

My company has a large presence on the East coast. From Florida up through Connecticut, we have offices with a wide variety of instrumentation spread out east of the Appalachian Mountains. I contacted our Maryland office inquiring if they had picked anything up. This morning, I was rewarded with 83 separate reports. We have remote units that call out if triggered in both Philadelphia and New York City. Every single one of those triggered, amounting to some 50 separate units calling out to say, "Oh wow! I got something! Let me show you!"

In my time here, I have experienced, although that's not the right word since I didn't wake up for any of them, three separate earthquakes. All have been minor, less than 3.5 on the Richter Scale. Some of our equipment triggered. Most did not mainly because the quakes happened between midnight and 6 a.m. when the equipment is 'sleeping'. So, to have a quake happen during the day when equipment would already be working is a joy.

Below is the waveform result which I thought was the coolest. The sensor is buried in the ground outside of a building which is in proximity to a limestone quarry.

You can see how it starts and how the vibration continues long after the machine's recording time ends. Quarry blasts are of short duration. Although this record is set for 8 seconds, we know the earth shook for over a minute. You can see the rolling of the earth here, what's called 'racking and shearing', as one side goes up and the other side goes down. The top channel being the biggest means, totally by accident, this sensor was pointed towards the area that moved. Those are the ground waves passing it by.

My son-in-law's second day of work was yesterday at the North Anna nuclear facility. His postings about how the plant efficiently shut down as the quake started were very reassuring. "Some stuff fell off the wall and a couple hoses detached, but that's it." Of course, later, there's more that they find, but it was still not of the magnitude it could have been.

Carole was at her job in Penneys. "Some shoes fell off displays, that's all mom." She said half her brain said, "OMG EARTHQUAKE!" while the other side said, "Hey, this is cool." She also said she can cross off her to do list, "Feel an earthquake".

One friend was grocery shopping and watched stuff fall off shelves. A guild mate was in an office in Boston and was ordered to evacuate. Another guild member was awakened from a nap. The best quote was from one of David's friends who wondered why the earthquake couldn't wait until the hurricane hit. "That could be followed by the locusts and the frogs."

This is a reminder that we live on a very dynamic planet. I was a bit worried about Carole and David when I read about the earthquake but I felt it wasn't of significant magnitude that they couldn't get home. When she called later, I was greatly reassured. Now, I can put all my worry energy into the torrential rains bound to come with Hurricane Irene.

Beverage:  Dr. Pepper


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