Saturday – August 6, 2016
Mount St. Helens National Monument
Pictures To Be Added Soon
A visit to Mount St. Helens is awe-inspiring. One cannot appreciate the destructive force of a volcanic eruption until the devastation to the surrounding landscape, that exists to this day, is seen first-hand.
Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is 96 miles south of Seattle, Washington, and 50 miles northeast of Portland, Oregon. The volcano is located in the Cascade Range and is part of the Cascade Volcanic Arc, a segment of the Pacific Ring of Fire that includes over 160 active volcanoes. This volcano is well known for its ash explosions and pyroclastic flows.
Mount St. Helens is most notorious for its eruption on May 18, 1980, at 8:32 a.m. PDT, the deadliest and most economically destructive volcanic event in the history of the United States. Fifty-seven people were killed; 250 homes, 47 bridges, 15 miles of railways, and 185 miles of highway were destroyed. A massive debris avalanche triggered by an earthquake measuring 5.1 on the Richter scale caused an eruption that reduced the elevation of the mountain's summit from 9,677 feet to 8,363 feet, replacing it with a one mile wide horseshoe-shaped crater. The debris avalanche was up to 0.7 cubic miles in volume. The Mount St. Helens National Volcanic Monument was created to preserve the volcano and allow for its aftermath to be scientifically
On March 20, 1980, Mount St. Helens experienced a magnitude 4.2 earthquake; and, on March 27, steam venting started. By the end of April, the north side of the mountain had started to bulge. On May 18, a second earthquake, of magnitude 5.1, triggered a massive collapse of the north face of the mountain. It was the largest known debris avalanche in recorded history. The magma in St. Helens burst forth into a large-scale pyroclastic flow that flattened vegetation and buildings over 230 square miles. More than 1.5 million metric tons of sulfur dioxide were released into the atmosphere. On the Volcanic Explosivity Index scale, the eruption was rated a five (a Plinian eruption).
When Mount St. Helens erupted, the collapse of the northern flank of St. Helens mixed with ice, snow, and water to create lahars (volcanic mudflows). The lahars flowed many miles down the Toutle and Cowlitz Rivers, destroying bridges and lumber camps. A total of 3,900,000 cubic yards of material was transported 17 miles south into the Columbia River by the mudflows.
For more than nine hours, a vigorous plume of ash erupted, eventually reaching 12 to 16 miles above sea level. The plume moved eastward at an average speed of 60 miles per hour with ash reaching Idaho by noon. Ashes from the eruption were found collecting on top of cars and roofs next morning, as far as the city of Edmonton in Alberta, Canada.
Mount St. Helens is geologically young compared with the other major Cascade volcanoes. It formed only within the past 40,000 years, and the pre-1980 summit cone began rising about 2,200 years ago. The volcano is considered the most active in the Cascades within the last 10,000 or so years.
Prior to the 1980 eruption, Mount St. Helens was the fifth-highest peak in Washington. It stood out prominently from surrounding hills because of the symmetry and extensive snow and ice cover of the pre-1980 summit cone. The peak rose more than 5,000 feet above its base, where the lower flanks merge with adjacent ridges. The mountain is 6 miles across at its base, which is at an elevation of 4,400 feet on the northeastern side and 4,000 feet elsewhere. At the pre-eruption tree line, the width of the cone was 4 miles.
Streams that originate on the volcano enter three main river systems: the Toutle River on the north and northwest, the Kalama River on the west, and the Lewis River on the south and east. The streams are fed by abundant rain and snow. The average annual rainfall is 140 inches, and the snow pack on the mountain's upper slopes can reach 16 feet. The Lewis River is impounded by three dams for hydroelectric power generation. The southern and eastern sides of the volcano drain into an upstream impoundment, the Swift Reservoir, which is directly south of the volcano's peak.
Between 1980 and 1986, activity continued at Mount St. Helens, with a new lava dome forming in the crater. Numerous small explosions and dome-building eruptions occurred. From December 7, 1989, to January 6, 1990, and from November 5, 1990, to February 14, 1991, the mountain erupted with sometimes huge clouds of ash.
Magma reached the surface of the volcano about October 11, 2004, resulting in the building of a new lava dome on the existing dome's south side. This new dome continued to grow throughout 2005 and into 2006. On January 16, 2008, steam began seeping from a fracture on top of the lava dome. Associated seismic activity was the most noteworthy since 2004. Scientists suspended activities in the crater and the mountain flanks, but the risk of a major eruption was deemed low. By the end of January, the eruption paused; no more lava was being extruded from the lava dome. On July 10, 2008, it was determined that the eruption had ended, after more than six months of no volcanic activity.
State Route 504, locally known as the Spirit Lake Memorial Highway, connects with Interstate 5 at Exit 49, 34 miles to the west of the mountain. The community nearest the volcano is Cougar, Washington, in the Lewis River valley 11 miles south-southwest of the peak. Gifford Pinchot National Forest surrounds Mount St. Helens.
Tomorrow another adventure begins.
Departed: Castle Rock, WA
Departure Time: 10:15 A.M.
Arrived: Kalaloch, WA
Arrival Time: 2:50 P.M.
Campground: Empty Commercial Lot for Sale
Latitude: N 46.28775
Longitude: W 122.79781
Elevation: 133 Feet
Camping Fee: Free
Campsite: Parking Lot
Campsite Hookups: None
Campground Amenities: None
Total Campsites: Several
Cellular Service: Verizon – 4G-3 Bars
Internet Service: Verizon Jetpack – 5 Bars
Dish TV Satellite Service: Excellent Service
Total miles traveled today: 137
South on OR-35
West on WA-14
North on I-205
North on I-5 to Exit 49