| Volcano | |
|---|---|
| Depth of deposit | From about 3 feet at volcano to less than 1 inch at blast edge |
| Velocity | At least 300 miles per hour |
| Temperature | As high as 660¡ F (350¡ C) |
| Energy released | 24 megatons thermal energy (7 by blast, rest through release of heat) |
How will you describe the eruption of Mount St. Helens?
A high-speed blast leveled millions of trees and ripped soil from bedrock. The eruption fed a towering plume of ash for more than nine hours, and winds carried the ash hundreds of miles away. Lahars (volcanic mudflows) carried large boulders and logs, which destroyed forests, bridges, roads and buildings.
What are the features of Mt St Helens?
At the event’s end, Mount St. Helens’s volcanic cone had been completely blasted away; in place of its 9,677-foot (2,950-metre) peak was a horseshoe-shaped crater with a rim reaching an elevation of 8,363 feet (2,549 metres). Further eruptions occurred until 1986, and a dome of lava grew intermittently in the crater.
What kind of eruption was Mt St Helens?
Summary of Events
A wave of decreasing pressure down the volcanic conduit to the subsurface magma reservoir, which then began to rise, form bubbles (degas), and erupt explosively, driving a 9-hour long Plinian eruption. Steam-blast eruption from summit crater of Mount St. Helens.
What was unique about the eruption of Mt St Helens?
On the morning of May 18, 1980, a volcano erupted not from its peak but from its side. In the minutes that followed, volcanic violence devastated the landscape, unleashing eight times more energy than was released by the sum of every explosive dropped during World War II, including two atom bombs.
What are 5 interesting facts about Mt St Helens?
Here are five facts about the stratovolcano.
- Before erupting, the volcano was 9,677 feet.
- Over 230 square miles of forest was destroyed in minutes.
- The volcano has had numerous eruptions.
- The blast killed USGS scientist David Johnston.
- Native Americans abandoned hunting grounds at the volcano 3,600 years ago.
What were 3 Effects of Mt St Helens eruption?
57 people lost their lives and hundreds of homes, buildings and structures were destroyed. After the eruption, the summit of Mount St. Helens was gone, forests were obliterated and rivers followed new courses. More than 150 new lakes and ponds were formed, and existing lakes filled with sediment, flooding their banks.
Is Mount St. Helens still active?
Mount St. Helens is the most active volcano in the contiguous United States, which makes it a fascinating place to study and learn about. Scientists receive many questions about the volcano.
What are the characteristics of stratovolcano?
Stratovolcano. Stratovolcanoes have relatively steep sides and are more cone-shaped than shield volcanoes. They are formed from viscous, sticky lava that does not flow easily. The lava therefore builds up around the vent forming a volcano with steep sides.
How many trees did Mt. St. Helens destroy?
| Volcano | |
|---|---|
| Trees blown down | 4 billion board feet of timber (enough to build about 300,000 two-bedroom homes) |
| Lahars | |
| Velocity | About 10 to 25 miles per hour (over 50 miles per hour on steep flanks of volcano) |
| Damaged | 27 bridges, nearly 200 homes |
What signs did the mountain give to warn that it was about to erupt?
An increase in the frequency and intensity of felt earthquakes. Noticeable steaming or fumarolic activity and new or enlarged areas of hot ground. Subtle swelling of the ground surface. Small changes in heat flow.
Did they know Mt St Helens was going to explode?
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.
What are 3 interesting facts about Mt St Helens?
Here are five facts about the stratovolcano.
- Before erupting, the volcano was 9,677 feet.
- Over 230 square miles of forest was destroyed in minutes.
- The volcano has had numerous eruptions.
- The blast killed USGS scientist David Johnston.
- Native Americans abandoned hunting grounds at the volcano 3,600 years ago.
What was unusual about the 1980 eruption of Mt St Helens quizlet?
The eruption was so large that the magma chamber under Crater Lake partially emptied, causing the volcano to become unstable and collapse.
Why is the St Helens volcano so famous?
The Mount St. Helens major eruption of May 18, 1980 remains the deadliest and most economically destructive volcanic event in U.S. history. Fifty-seven people were killed; 200 homes, 47 bridges, 15 miles (24 km) of railways, and 185 miles (298 km) of highway were destroyed.
What animal survived Mt St Helens?
Gophers were able to survive underground after the 1980 Mount St. Helens eruption and helped plants thrive again.
Why did Mount St. Helens erupt kids?
A massive debris avalanche, triggered by a magnitude 5.1 earthquake, caused a lateral eruption that reduced the elevation of the mountain’s summit from 9,677 ft (2,950 m) to 8,363 ft (2,549 m), leaving a 1 mile (1.6 km) wide, horseshoe-shaped crater.
What was the biggest danger of Mt St Helens?
Huge mudflows rushed down the Toutle and Cowlitz rivers, destroying hundreds of bridges, homes and buildings. The eruption killed 57 people and caused millions of dollars in damages.
How did the eruption affect the people?
If inhaled, volcanic ash can cause breathing problems and damage the lungs. Inhaling large amounts of ash and volcanic gases can cause a person to suffocate. Suffocation is the most common cause of death from a volcano.
What were the significant effects of eruption?
Volcanoes spew hot, dangerous gases, ash, lava, and rock that are powerfully destructive. People have died from volcanic blasts. Volcanic eruptions can result in additional threats to health, such as floods, mudslides, power outages, drinking water contamination, and wildfires.
For a limited time, some people living near the eruption suffered from post traumatic stress syndrome: depression, troubled sleep, irritability, ans a sense of powerlessness. From 1980-1990, 74 research projects were funded by the National Science Foundation at a total cost of just less than $5 million.