The eruption started as a lateral blast at the site of the bulge. Eruption blew off the top of the volcano and lowered the summit by 410 meters. Largest eruption in U.S. in recent times. Ejected about 1 km 3 of volcanic debris. Drastically modified many square miles of landscape north of the mountain.
Resurgent dome continues to grow and slowly fill the crater.
Increasing the temperature decreases the viscosity. Increasing the silica content increases the viscosity. Increasing gas content increases mobility of the magma. Gases dissolved or compressed in a magma can quickly expand when a magma reaches the earth's surface. Very fluid basaltic magmas can let much of the gas escape the vent with relative ease.