Jackson Hole Quake Swarm Mystifying
Something strange may be afoot - underfoot, actually - in northwest Wyoming.
WYOMING - Last Friday, the legendary Steamboat Geyser in Yellowstone National Park erupted for the first time in two years.
The rare eruptions at Steamboat, considered the world's largest active geyser, are one of the most sought-after events for the throngs of "geyser gazers" who frequent Yellowstone.
Unfortunately, no one was there when Steamboat blew, said Cheryl Matthews, a park spokeswoman.
Park officials figure the eruption in the Norris Geyser Basin happened sometime between 6 p.m. and 8 p.m. April 26. They expect to have a more precise estimate once researchers can collect data in the area.
Meanwhile, geologists are keeping busy with events farther south.
They say there has been an usually large number of small earthquakes and a few other odd occurrences around the town of Kelly, northwest of Jackson.
The action in Jackson Hole and at Steamboat is probably not related, geologists say.
"It's unlikely there's a tie," said Jim Case, head of geologic hazards at the Wyoming State Geological Survey.
A huge, underground magma chamber drives most of the Yellowstone geyser system. The earthquakes near Jackson "are tied into a different mechanism," Case explained.
Though earthquakes are nothing new to the Jackson area - huge seismic events shaped the Teton Mountains and the surrounding area - geologists are raising their eyebrows at the frequency of quakes in a tight area near Kelly.
Since the beginning of the year, there have been 31 small earthquakes - the most recent on Wednesday - with a magnitude of 2 or greater located 1.5 to 3 miles south of Kelly, according to local and state scientists. Only 25 earthquakes were reported within 6 miles of that area between 1986 and September 2001.
Local geologists also have reported strange odors, increased gases in wells and ponds, and the curious stop and start of the nearby National Fish Hatchery spring.
What does it mean?
No one knows for sure. It could point to a larger, impending earthquake. It could just be harmless underground rumbling.
Scientists are saying that no one should jump to any conclusions about this latest cluster of earthquakes, which are known as swarms.
"The fact that you have a swarm is not necessarily indicative that something bigger is coming. You don't send up the red flare immediately just because you have a swarm," Case said. "There's just not enough data to scare anyone."
It's common to see many small earthquakes scattered throughout northwest Wyoming. Most have not been precursors to larger seismic events, but some have.
What's unusual near Kelly is that the earthquakes are so tightly grouped, Case said.
Aside from the earthquakes, scientists are curious about what might be causing abrupt changes in water flows near the hatchery.
David Susong, a hydrologist with the U.S. Geological Survey in Salt Lake City, said changes in the ground water levels and spring flow can sometimes be linked with earthquake activity. Wyoming's extended drought also could be a factor, he said.
"It is very unusual behavior for spring flow to stop and restart, especially in the spring season, which is usually a time when ground water is recharging as the snow melts and spring flows increase," he said.
Peculiar odors and gases in local wells also have raised questions. It's too early to say whether all the recent events are connected, Case said.
"To say it's all earthquake-related, I just couldn't say that," he said.
Geologists of Jackson Hole, a group of professional geologists, put the word out this week about the Kelly earthquakes partly because they wanted to remind people that they live in earthquake country, according to Wally Ulrich, the group's vice president.
"There was an awareness level that we wanted, but it's not something people should panic about," Ulrich said. "We wanted to make sure people were prepared."
He acknowledges that the area is rife with the possibility of a large quake.
"The Teton fault has been ominously silent for a long time," he said. "But there's no way to predict these things."
Back at Yellowstone, scientists and geyser watchers also are struggling with predictability - especially at Steamboat.
To have such a rare eruption at Steamboat without any witnesses may be frustrating, but that unpredictability is part of what makes the geyser so popular.
The latest eruption before last Friday's was on May 2, 2000.
A couple in the Norris parking lot awoke to a load roar and tremors early in the morning. Fearing an earthquake, they fled, only to see the geyser erupting behind them for the first time in more than eight years.
Sometimes compared to a train at full speed, Steamboat is known for huge blasts that last anywhere from 3 to 40 minutes. The column of water can reach 250 to 400 feet high. The steam phase afterward can last up to 12 hours.
Quite a few people saw the steam phase after Friday's eruption, according to Matthews, the Yellowstone spokeswoman. But it's still unclear how big the eruption was. Matthews said park researchers will look at how much water flowed into the nearby Gibbon River after the blast.
"We're hoping that maybe it will show a huge surge of water," she said.
• Story originally published by:
Billings Gazette / MO | Mike Stark - May 03.02
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