2023年10月30日 · Prior to 1980, Mt. St. Helens had the shape of a conical volcano sometimes referred to as the Mount Fuji of America. During the 1980 eruption the upper 400 m (1,300 ft) of the summit was removed by a huge debris avalanche, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome and a glacier.

The 275,000 year old geologic history of Mount St. Helens has displayed both relatively quiet outpourings of lava and violent explosive eruptions of volcanic ash and rock fragments, known as tephra. Volcanologists have separated the eruption history of this volcano into four main stages, each followed by a dormant, nonexplosive period.

2023年11月9日 · Volcanism occurs at Mount St. Helens and other volcanoes in the Cascades arc due to subduction of the Juan de Fuca plate off the western coast of North America. Over its rich and complex 275,000-year history, Mount St. Helens has produced both violent explosive eruptions of volcanic tephra and relatively quiet outpourings of lava.

Mount St. Helens was recognized as a volcano at least as early as 1835; the first geologist apparently viewed the volcano 6 years later. James Dwight Dana of Yale University, while sailing with the Charles Wilkes U.S. Exploring Expedition, saw the peak (then quiescent) from off the mouth of the Columbia River in 1841. ...

6. Scientists and public officials have become better prepared to face volcanic threats. After Mount St. Helens erupted, residents of the Pacific Northwest wanted to know what the volcano would do next. Scientists, land managers, and public-safety officials coordinated their efforts and a new era of volcano crisis management was born.

Mount St. Helens is the most active volcano in the contiguous United States, which makes it a fascinating place to study and learn about. ... Before May 18, 1980, Mount St. Helens' summit altitude of 9,677 feet (2,950 meters) made it only the fifth highest peak in Washington State. It stood out handsomely, however, from surrounding hills ...

2023年11月7日 · A "bulge" developed on the north side of Mount St. Helens as magma pushed up within the peak. Angle and slope-distance measurements to the bulge indicated it was growing at a rate of up to five feet (1.5 meters) per day. By May 17, part of the volcano's north side had been pushed upwards and outwards over 450 feet (135 meters). (Lipman, Peter.

2023年11月2日 · The Mount St. Helens National Volcanic Monument is within the Gifford Pinchot National Forest and managed by the USDA Forest Service. The Monument was established in 1982 to designate 445 km 2 (110,000 acres) around Mount St Helens for research, recreation, and education. Within its boundaries, the area that was impacted by the cataclysmic eruption …

2023年10月30日 · MOUNT ST. HELENS (VNUM #321050) 46°12' N 122°10'48" W, Summit Elevation 8363 ft (2549 m) Current Volcano Alert Level: NORMAL Current Aviation Color Code: GREEN. ... No changes have been detected in ground deformation, volcanic gas or thermal emissions at Mount St. Helens. No changes have been observed at other Cascade Range …

2023年11月8日 · Mount St. Helens has produced four large explosive eruptions during the past five centuries that affected the Pacific Northwest region and sent large amounts of volcanic ash downwind. Owing to these factors, USGS maintains a robust monitoring program at the volcano to detect signs of renewed unrest and works with Federal, State, and local ...