Here is another seismogram reading about 2 hours later, its still going!
Let me give you some background so you know kinda what you are looking at. This is a seismogram readout from a seismometer located in Tucson. It records shaking in the earth. Most of the readouts on this machine are totally unfelt be humans, but the sensitivity of the machine is such that it picks up vibrational waves as they pass by. The earthquake was powerful enough in Chile to be very strongly noticed by the machines. There is resonant readings as the waves reflect within the earth. Kinda like when you splash in a pool of water. Although you might not be right next to someone who is splashing, you can see waves caused by it go by, and then as the waves reflect off the sides of the pool and go by again.
Here is an intensity map of the earthquake from the USGS:
4 comments:
Ypou need to explain this one to me. Is this normal or did you guys have some big quakes out there?
Dad
Thanks for the expanation. I understand a little better. The movement, is it from the Chile quake or is it local? Is it a precursor to something bigger (should I be panicing now?). Are you going to be putting scary stuff on this site all the time? :)
Dad
lol, no this isnt scary stuff at all. When an earthquake happens, there are 2 types of seismic waves generated. The first is called a P wave. it is compressional much like sound is going through air. This however travels through the earth and speeds much faster than sound though. the 2nd type and the dangerous type is called a S wave. It is like the kind of wave where you make a wave in a streched out rope or wire. It is dangerous because of it's shear. it moves from side to side, and that what causes the damage. S waves dissapate quickly (see the USGS shake map), the p waves traveled from chile to both AZ an NH in about 20 minutes, then reverberated inside the earth for about 4 hours. The seismogram reading is essentially like putting a microphone in the earth and listening to it grumble. This earthquake, because of its magnitude, was a loud grumble. There are quiet grumbles too, like mining explosions, or large trucks driving near the seismogram. I'll post a new post explaining this to dissolve any confusion that you may still have.
We actually were in So. Cal. when there was a mild one, probably 1974-75 I think. I was upstairs sleeping and Dad was downstairs on the couch...and no, he wasn't in trouble, he had had some surgery and slept better on the couch!...anyway it only lasted maybe 15 seconds, nothing fell off walls or anything but it was a weird sensation to wake up to the bed shaking,.we just are so accustomed to terra firma being well, firm, that it is almost too hard to grasp when it isn't!
Boy, Rob, do you really love this stuff, it shows big time. I am so happy for you to have found something, besides computers, that you have a passion for and a real grasp of. Way to go!
Much love to my favorite son-in-law. Okay, so you are, and will always be, my only son-in-law, but I couldn't ask for a better one, I mean it.
Love ya =)
Mom
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