VANCOUVER, Wash. -- A magnitude 3.1 quake at 5:32 a.m. caused a rockfall and ash cloud at Mount St. Helens that quickly dissipated.

The U.S. Geological Survey said the quake was not a significant change in seismicity at the volcano where a minor eruption has been under way for nearly two years.

Officials said they believe there is little danger from new rock pushing into the crater. They allowed climbers back on the volcano last week to climb to the crater rim.