What鈥檚 rumbling beneath Yellowstone? Hundreds of tremors have been rippling through the national park in Wyoming from late December to early January, prompting worries that the shaking may trigger dangerous steam explosions.
The motion of magma and hot fluid permeating the rock beneath Yellowstone is thought to be responsible for the thousands of small earthquakes recorded in and around the park each year. These everyday quakes usually go unnoticed by people on the surface.
Since 26 December, however, a much more powerful swarm of quakes has shaken the area. The strongest were easily felt by visitors and park staff, including one with a magnitude of 3.9.
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These were still too small to cause damage directly, but there were worries that the vibrations might cause pent-up steam to burst through the surface with explosive force. Yellowstone is pockmarked with craters thought to have been produced in this way, and geologists estimate an explosion big enough to create a 100-metre-wide crater happens there every 200 years or so.
Reassuringly, as New 杏吧原创 went to press, the quakes appeared to be subsiding. 鈥淚t hasn鈥檛 stopped, but it鈥檚 reduced markedly in the last couple of days,鈥� said Robert B. Smith of the University of Utah, Salt Lake City, on Monday. There are no signs of volcanic eruptions on the way either, says Smith, who monitors Yellowstone鈥檚 geological activity.
The quakes appear to be concentrated along a fault beneath the park. Further analysis should reveal their cause, such as forces associated with the fault or the activity of hot fluids underground.