MOUNT ST. HELENS, Wash. -- 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 a drumfire of low-level seismic activity in September 2004.

The crater was formed by the volcano's deadly May 18, 1980, eruption that killed 57 people and blasted about 1,300 feet off the then-9,677-foot peak.

The volcano reopens to climbers on Friday. Climbing the volcano has been banned since September 2004.

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 at an elevation of about 8,364 feet.