November 27, 3003 (Ira Pilgrim)
Everyone gets excited about a great earthquake. However,
even a microearthquake can be an exciting event if you happen
to be right on top of it.
On Monday, November 17, 2003 I was in my bedroom reading when there was a loud explosion and a fraction of a second later, my house gave one immense shake, as if it had been hit by an immense truck. I looked at my watch; it was 2:48 PM. Was it an explosion or an earthquake? Since my house was intact, it seemed more likely that it was an earthquake, although I had never experienced an earthquake accompanied by a loud boom.
I went to my computer to the U.S. Geological Survey's earthquake web site (http://quake.wr.usgs.gov). This marvel of the computer age tracks earthquakes. Every earthquake that occurs is recorded by a large number of seismographs. The computer integrates the information and pinpoints the location, depth and magnitude. From their home page, I went to "Real Time Earthquake Maps, California-Nevada." I then went to their page on "recent quakes." There was a map of California with colored squares on it. The size of the square indicates the magnitude of the quake and the color of the square, when it occurred. Red squares indicate quakes that occurred in the last hour. There was one red square not too far from my home and I clicked the cursor on it. A page appeared. The time of it's occurrence was 2:48 PM. The quake had occurred 8 miles north of Laytonville. That is where I am. It was magnitude 2.8, which classifies it as a microearthquake. It didn't seem micro to me.
I then clicked on a link that said "Topo map centered at earthquake" which took me to www.topozone.com (a map company) and on their 1:100,000(Large) scale was my area. A high cliff marked White Rock was there. I built my house on the top of that cliff, about `100 yards away from the edge. On the map, about half a mile away from my house was a small red cross which marked the epicenter of the quake that had occurred 3.5 miles down. In other words, I was almost on top of where the quake had occurred.
I phoned some of my neighbors. The only one who had felt it was the person whose house was on the property next to mine.
Okay, so it was an earthquake almost right under me, but how come the loud noise that preceded the shake? I phoned the University of California at Berkeley's Seismological Laboratory and got to talk to a seismologist. I told her what happened and asked about the boom. She said that people who are right next to the epicenter of a quake sometimes report a noise. She said that the noise resulted from the first wave (the P wave) which vibrated my house, causing the sound; the second wave (the S wave) shook the house. I asked if it couldn't have been an explosion and she explained that a magnitude 2.8 quake could not be produced , even by a large quantity of conventional explosives. It was extremely unlikely that someone had exploded an atomic bomb 3.5 miles below my house. So that was it, it was definitely an earthquake.
I designed and built my house myself and made sure that it was firmly anchored into the rock that it was built on and that the rods from the anchors fastened to sturdy brackets on the wall studs. All of the fastenings are heavy duty and all of the glass is tempered glass.
I spent the next two days congratulating myself on the fine job that I had done in earthquake-proofing my house. And I am still gloating.
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