Earthquake warning issued for Jackson Hole-
by Ralph Maughan. May 1, 2002.
Today, May 1, the Jackson Hole News and the Jackson Hole Guide reported that Geologists of Jackson Hole, a group of local professional geologists, was warning the public that a swarm of earthquakes a few miles south of Kelly, Wyoming (that would be on the National Elk Refuge) might indicate a large quake was on the way.
An unusual number of small quakes have occurred in the area since the beginning of the year. Moreover, the springs at the National Fish Hatchery on the Refuge recently stopped flowing and then restarted at about 60% of the previous volume. The geologists reported that there have been reports of peculiar odors and increased gases in wells and ponds in the Jackson Hole area.
Northward inside Yellowstone National Park, the world's biggest geyser, Steamboat, at Norris Geyser Basin, made a rare eruption on Friday night, April 26. Earthquakes and unusual geyser activity are sometimes connected.
Thirty-one small earthquakes were recorded in the area south of Kelly since the beginning of the year. Small quakes there are not unusual, but there were only 25 in the previous 15 years. The quakes were in the same location, but involved several faults.
The geologists cautioned that they couldn't say whether a large quake would actually occur in the near future.
The Teton Range and valley of Jackson Hole are the result of earthquakes. The bold face of the Tetons is the result of thousands of big earthquakes with estimated magnitudes of 7 to 8 on the Richter Scale over the past 13-million years. 16,000 feet of movement has occurred, although the present relief of the range is at a maximum, 7000 feet. Erosion from the mountains and fill from glaciers obscures how much the mountains rose and the valley sank.
The last large quake in the area was in 1983 -- the Mount Borah quake about 150 miles to the west, in the Lost River Range, which has a profile similar to the Tetons. The Borah Peak quake measured 7.3 on the Richter Scale and left a fault scarpe as high as 15 feet that runs for about 10 miles along the base of the Range.
A series of small quakes near Kelly in the 1920s eventually brought down a huge landslide in 1925. On June 23, 1925, after a wet spring, a large chuck of mountain gave way, making a dam in the Gros Ventre Canyon about 4 miles upstream from Kelly. Lower Slide Lake gathered behind the dam. On May 18, 1927, the upper 50 feet of the landslide dam gave way, washing away Kelly, flooding Wilson, Wyoming downstream, and causing flooding all the way to Idaho Falls, Idaho. Six people drowned as did hundreds of animals.