The mountain is 6 miles (9.7 km) across at its base, which is at an elevation of 4,400 feet (1,300 m) on the northeastern side and 4,000 feet (1,200 m) elsewhere. At the pre-eruption tree line, the width of the cone was 4 miles (6.4 km).
How wide was Mt St Helens eruption?
The 600 km2(230 mi2) devastated area was blanketed by a deposit of hot debris carried by the blast. Sources/Usage: Public Domain. Plinian eruption column from May 18, 1980 Mount St. Helens.
How big was the bulge on Mt St Helens?
450 feet
Today in science: On May 18, 1980, Mount St. Helens underwent a catastrophic and deadly eruption, triggering the largest landslide ever recorded. Earlier in the year, thousands of small earthquakes, venting steam, and a growing bulge protruding 450 feet (140 m) indicated that magma was rising in the volcano.
What was the blast radius of Mount St. Helens?
The blast devastated 596 square kilometers (229 square miles) and destroyed timber valued at several millions of dollars. The photograph in the poster shows Mount St.
How far did ash spread from Mt St Helens?
During the 9 hours of vigorous eruptive activity on May 18, 1980, about 540 million tons of ash from Mount St. Helens fell over an area of more than 22,000 square miles (57,000 square kilometers).
Is Mt St Helens bigger than Yellowstone?
The three caldera-forming eruptions at Yellowstone (2.1 million years ago, 1.3 million years ago, and 640,000 years ago), were respectively about 2,500, 700, and 1,000 times larger than the 1980 eruption of Mt. St. Helens in the state of Washington.
How far was the Mt St Helens eruption felt?
(AP) — Mount St. Helens erupted yesterday with a violence blast that blew 600 feet off its summit. the eruption was felt 200 miles away, belching ash and hot gas that blotted out the sun for more than 100 miles. At least nine people were killed.
How far away were trees blown down Mt. St. Helens?
Helens were obscured. The inevitable blast extended over an arc of 170° centered to the north. It bashed and seared trees beyond 28 km from the cone (Fig. 2.1).
How far away was the furthest victim from Mt. St. Helens?
During the eruption, 57 people were killed. 7: How far away was the furthest victim? The farthest victim was about 13 miles away.
Did they know Mt. St. Helens was going to erupt?
In 1980, Mt St. Helens’ continued seismicity warned scientists at monitoring stations that the volcano might erupt, but the danger zone around the mountain turned out to be much too small.
How big was Mt St Helens eruption compared to atomic bombs?
In total, Mount St. Helens released 24 megatons of thermal energy, seven of which were a direct result of the blast. This is equivalent to 1,600 times the size of the atomic bomb dropped on Hiroshima.
How loud was Mt St Helens?
163 decibels
On 18th May 1980, Mount St Helens erupted in Skamania County, Washington. The force was enough to blow down trees 16 miles away and it was seen on the Space Shuttle from outer space. The sound measured 163 decibels and the force blew windows out up to 200 miles away in Seattle!
How much of the top of Mt St Helens blew off?
12 percent
The May 18 eruption left a crater approximately 1 mile wide and 2 miles long. An estimated 1 cubic mile of rock or 12 percent of the mountain was removed during the eruption. Elevation of the mountain was reduced by approximately 1,370 feet from 9,677 to 8,307 feet.
How long does ash stay in the air?
So, how does the ash get spread so far from the site of the eruption? The simplistic view of ash behavior in the atmosphere would suggest that very small (> 30 μm) ash should stay aloft for days to weeks – the settling rate is between 10–1 to 10–3 m/s if you apply Stokes Law to the settling of the ash.
How long did Mt St Helens ash cloud last?
Ashfall Zone. After the landslide and blast, a 15-mile (24 km) high column of ash pumped ash into the atmosphere for nine hours. The massive plume of volcanic ash drifted to the northeast. Ash was deposited across western states and the ash cloud eventually encircled the globe.
How far did the lava flow from Mt St Helens?
Lava flows from Mount St. Helens typically affect areas within 6 mi (10 km) of the vent. However, two basalt flows erupted about 1,700 years ago extended about 10 mi (16 km) from the summit; one of them contains the Ape Cave lava tube. Sources/Usage: Public Domain.
What are the 3 super volcanoes in the US?
Three of the seven supervolcanoes are located in the continental US: Yellowstone, the Long Valley Caldera, and the Valles Caldera. The most well known supervolcano is in Yellowstone National Park, Wyoming (shown above).
What is the biggest supervolcano on Earth?
Taupo erupted 22,600 years ago and is the most recent supereruption on Earth (with a volume of about 1,130 cubic kilometers). Additional volcanoes capable of producing supereruptions include the large caldera volcanoes of Japan, Indonesia, and South America.
What is the most powerful volcano on Earth?
Rising gradually to more than 4 km (2.5 mi) above sea level, Hawaii’s Mauna Loa is the largest active volcano on our planet. Its submarine flanks descend to the sea floor an additional 5 km (3 mi), and the sea floor in turn is depressed by Mauna Loa’s great mass another 8 km (5 mi).
How long did it take to clean up Mount St. Helens?
Mount St. Helens: 40 Years of Recovery | Earth And The Environment.
Did Mt. St. Helens ash go around the world?
Helens , in Washington State, erupted 40 years ago today. The largest landslide in recorded history filled valleys below with debris, and ash fell from the sky for weeks, blanketing the nearby area and affecting regions as far away as the Rocky Mountains. Within just two weeks, ash from the blast had circled the globe.