Magnitude 3.6 Quake Closes Mount St. Helens Again
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MOUNT ST. HELENS -- A magnitude 3.6 earthquake shook Mount St. Helens Tuesday morning, one of the largest earthquakes recorded during the ongoing eruption, the U.S. Geological Survey said.
The 9:56 a.m. quake triggered significant rock falls from the lava dome and crater walls that sent plumes of dust to the rim.
Lava has continued to push into the crater -- most recently forming a sheer rock fin -- since the 8,364-foot mountain reawakened with low-level seismic activity in September 2004.
That prompted closure of the mountain to climbers.
The crater was formed by the volcano's May 18, 1980, eruption, which killed 57 people and blasted about 1,300 feet off the 9,677-foot peak.
The volcano reopens to climbers on Friday.
The National Volcanic Monument limits the number of climbers to 100 a day and requires a permit available online through the Mount St. Helens Institute.
Before the latest eruption, more than 10,000 climbers took the 5-mile hike to the rim of the mountain, at an elevation of about 8,364 feet.