Mount St. Helens may have signaled a new wave of eruptions
When Mount St. Helens exploded with cataclysmic fury in 1980, many Americans regarded it as an isolated example of nature on the rampage. Geologists, however, have long known that the restless mountain was only one of many dormant volcanoes in the American West. Although some have not stirred in tens of thousands of years, there is no assurance that one or more will not erupt again, perhaps in the near future. As scientists say, "There is no such thing as a dead volcano."
To assess when these sleeping giants might violently reawaken, the U.S. Geological Survey (USGS) has been conducting a long-term study of volcanic hazards in the U.S. In an interim report, it has made public a list of 33 volcanic sites in the Western states, Alaska and Hawaii that could go off at almost any time. While the report carefully makes no predictions, it notes that some volcanologists fear that the eruption of Mount St. Helens, as well as other recent signs of seismic unrest in the U.S., may hint at the onset of a period of more intense volcanic activity for Americans.
The initial indication of such terrestrial turmoil came in 1975, when Mount Baker, a 10,750-ft. volcanic peak in northwestern Washington, began to puff and fume. Vented steam has continued to melt ice around the summit crater of the mountain, which is only 90 miles from Seattle. The Geological Survey says that rising magma in the mountain's cone may be stoking Mount Baker's internal fires. Magma is hot, melted rock from deep within the earth that fuels volcanoes and becomes visible as lava when it breaks through the crust.
The rise of magma is often accompanied by swarms of small local earthquakes. Such tremors, which enable scientists to estimate how close to the surface the magma may be, have been felt at Mount Hood in neighboring Oregon and at Mount Shasta in Northern California as well as Mount St. Helens. In addition, the USGS study notes that since 1982 earthquakes have shaken California's Coso Range, a volcanic region west of Death Valley; Yellowstone National Park, which is famed for its hot springs and geysers, notably Old Faithful; and Mammoth Lakes, a popular California ski resort near the Nevada border.