Lava Dome Begins To Rebuild Summit |
![Mount St. Helens on May 19, 1982. USGS Photograph by Lyn Topinka](global/images/usgs19.jpg)
Mount St. Helens on May 19, 1982.
USGS Photograph by Lyn Topinka
|
After the May 18, 1980 eruption, thick pasty lava crept
onto the crater floor, building a lava
dome. Pressure from steam and volcanic
gas caused this dome to explode,
sending hot rocks across the crater floor.
Over the next six years this cycle of
dome building eruptions and destructive
explosions occured several times.
Geologists monitored earthquakes, gas
emissions, and surface deformation to
help forecast impending eruptive
activity.
When the last dome building eruption ended in October
of 1986, the dome was 900-feet tall and 3000-feet wide. Today,
the crater and lava dome are often cloaked in a haze of dust
resulting from rocks falling from the crater walls and occasional
wisps of steam from the lava dome. |