Saturday, January 17, 2009

Thursday's Grand Teton Quake

Jackson Hole Daily reported a 3.7 magnitude quake near the Grand Tetons Thurday evening. The University of Utah's map shows the earthquake's location at 8 miles SW of Hoback, Wyoming. This one is definitely farther away from the Yellowstone earthquakes and I really don't know how all the faults in that area are connected. This earthquake occurred at the "south end of a seismic gap that extends into Yellowstone National Park. I had to look up what a seismic gap is. According to Wikepedia: "A seismic gap is a segment of an active geologic fault or subduction zone that has not slipped in an unusually long time; they are often considered susceptible to future strong earthquakes." According to the USGS visual glossary: "A seismic gap is a section of a fault that has produced earthquakes in the past but is now quiet. For some seismic gaps, no earthquakes have been observed historically, but it is believed that the fault segment is capable of producing earthquakes on some other basis, such as plate-motion information or strain measurements." According to Planet Jackson Hole Online the earthquake swarms in Yellowstone are at the north end of this seismic gap.

On January 7, 2004 Teton county was hit by four earthquakes, magnitudes of 5.0, 3.7, 4.1, and 4.0. These quakes were preceded on December 30, 2003 by a 3.5 magnitude quake. Even farther back, in 1925 there were small quakes reported in the same area.

The Wyomic State Geologic Survey has .pdf files with records of earthquakes throughout Wyoming listed by county. I looked up the Teton County information. It has a different earthquake scale the Mercalli Intensity Scale , which I was not familiar with. It is a long read, but for those who are interested in the geology of this area, it has a more complete history of the quakes in Teton county.

I think it interesting that both the Jackson Hole Daily and the Planet Jackson Hole online include earthquake precautions. Most of the quakes historically have been relatively minor, but anyone who lives in an area that could experience an earthquake, should be familiar with what to do when an earthquake happens. I grew up in Girl Scouts, and participated in both Cub Scouts and Girl Scouts with my children. Both have the motto: Be prepared. Taking the time to look over these guidelines, to talk them over with your family, to check out your house or apartment, being careful what you hang over your bed, having canned goods on hand . . . these are things that don't require a lot of time, but could save you and your loved ones lives.

But . . . after you have studied up on what to do before and after an earthquake happens and have taken what ever preparatory actions seem prudent, then file the information in your brain. Don't waste time needless worrying about a big earthquake that may not happen in your lifetime. The probability is that these are just normal small quakes part of our planet's normal shifting. It is wise and prudent to stay informed about the quakes in your area, but it is not healthy to go into a panic mode over something that "could" happen, but probably won't.

I'm following the news about the quakes, because I love the area and find this real time geologic activity fascinating.

No comments: