A hazard is a situation that poses a level of threat tolife, health, property or environment. The level of hazard posed by different volcanoes can very greatly, from a weak eruption with minimal impact that causes little damage, to a voilent and life threatening explosion. Most of the sixty-plus volcanoes that erupt each year are low risk, however a combination of factors can cause a volcano to be a serious hazard. The factors causing these variations will be explained in this essay.
The volcanoes are located where there is a divergence or convergence in the tectonic plates and bring their lava from the deepest of the terrestrial mantle. The materials and explosions of these ginates represent a constant risk in the places inhabited by the human being, nevertheless the people ususually live in these areas no matter the risk. On the other hand the volcanos can change the geology of an impressive form, or to cool the temperature of the earth, or to darken the sky. The scientific community increases its efforts to try to understand better what happens in volcanoes, however it is impossible to predict these conditions.
The cataclysmic eruption which caused the collapse of the caldera and the deposition of the Bishop Tuff was an explosive, fast event. It ejected coarsely porphyritic biotite rhyolitic ash and viscous lava with an approximate silica content of 76 percent. The total ejecta came to about 600
It is believed that this volcanic area was caused by a localised hot spot within the Pacific plate. A concentration of radioactive elements inside of the mantle may have caused this hot spot to develop. The hot spot is stationary so as the Pacific plate moves over it a line of volcanoes are made. This is more proof that the Earth’s crust is moving as suggested by Wegener.
As the eruption wore on, it later produced a phase with red hot pyroclastic surges and flows, along with other volcanic material. This was referred to as the “Peléan” phase. These type of eruptions are known for the mentioned pyroclastic flows, along with hot mud surges. (Universe today) This phase was speculated to have begun during the latter part of the eruption, and is largely regarded as the main killer of most of the surrounding inhabitants. (Museum timeline)
The Rift has affected the volcanic activity over the years that it has been there. This is because as the plates push apart from eachother, they push up against other tectonic plates which creates the structure of the volcanoes. As the plates push up against eachother the edge of the plates have nowhere to go but up. The divergence of the plates has also been the cause of several dormant volcanoes created in Africa such as Mount Kilimanjaro, Mount Elgon and Mount Meru.
The damage of this explosion was deadly. The eruption cased over 57 deaths. Every single tree in the forest and on the mountain fell down and burned. Ash blew everywhere. Cars on the road got stuck in ash and people could not get out. They suffered and died. During the explosion the top blew off, witched caused 1,300 feet difference.
Ask anyone in the Pacific Northwest to name a volcano in the area and you will most likely get the response of “Mount St. Helens”. There is good reason for this particular volcano to have gained such a great reputation for itself, and that is the eruption which occurred in 1980. Beginning in March, new systems of seismographs were being implemented to track the size of earthquakes that were happening in the St. Helens area. Earthquakes were recorded up to three times a day almost daily and on March 27th, an official warning was sent out as one of the quakes caused a stream of ash over 6,000 feet into the air. On the morning of May 18th, 8:32am, an earthquake measuring in at a magnitude of 5.1 on the seismograph signaled the beginning of the eruption.
Volcano eruptions happen more often that you know it. They even happen in Alaska. Earlier this year a volcano in Alaska had erupted. This was Pavlof Volcano. This massive eruption had a large cloud of ash and debris more than 7 miles into the air. Pavlof Volcano is 625 miles southwest of Anchorage. Lava shooting out of the volcano was seen by many people near the area. Strong winds had also carried a lot of ash and debris throughout the interior of the state.
Helens was a huge eruption that happened May 18th, 1980. 57 people died from the smoke. By April it was growing 5ft per day. The mushroom clouds of ash and gases more than 12 miles into the air.” states livescince. “The shock wave went 19 miles” state's fs.usda.gov. Such pulse indicated magma was on the move. On May 18, there were hundreds of earthquakes that day. The eruption lasted 9 hours. The Mount St. Helens erupted at 8:32 A.M. It went as high as 1,300 feet (396 meters). Biggest eruption over 100 years. “The first eruption of steam from the summit sent a column of ash, snow and, steam 6,000 sent into the air”, livescince.gov There were a lot of things going on that day and
On the morning of May 18, 1980, the United States of America experienced its deadliest and most destructive volcanic eruption in history. Briefly succeeding a magnitude 5.1 earthquake, an enormous slab of Mount St. Helens northern flank collapsed in a massive debris avalanche. This landslide was the largest to transpire on Earth in recorded history and caused the volcanoes magma system to depressurize. With the cap of the mountain removed, superheated gases and rock fragments blasted through the side of the mountain (USDA, 2005). The lateral blast accelerated at speeds of 480 km per hour and reached temperatures of 350 °C, creating an immense area of leveled and scorched forestry. Surges of water from melting snow and glaciers capping
Considering there was such devastation from the May 8th eruption there was a few eye witnesses who were able to give their accounts on what happened that day. On the night of May 2, a small eruption of Mount Pelée meant that the town’s attention was fully on it. Witnesses said Pelée’s summit seemed to catch fire, spewing glowing rocks and rendering the midnight sky incandescent. The morning of May 3rd, the residents of St. Pierre found birds that had fallen from the sky, as they were weighed down by ash. Reports of a steamer captain noticing dead fish floating in the sea could have meant that the fish had been killed by a submarine earthquake that sent a shock wave through the sea. Within Ellery S Scott’s account of the 1902 disaster he claimed that the volcano threatened as early as 3rd may when the smoke came from the crater as well as ‘the people of Le Precheur, at the very base of the western slope of Pelée had for some time been smelling sul-phurous gases in the air, the forerunner of the great outburst that was even then ma¬king ready to shoot forth from beneath the rocky crust of the volcano.’ These signs should have given the people of Saint Pierre enough chance to evacuate.
But there are some anomalies as there are earthquakes which don’t take place on a plate boundary and it’s the same with volcanoes. An example of this is Hawaii. Hawaii is a volcanic island which is found in the middle of a tectonic plate. Hawaii is an example of a hotspot. The places known as hotspots are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be on, near to, or far from tectonic plate boundaries. There are two hypotheses to explain them. One suggests that they are due to hot mantle plumes that rise from the core-mantle boundary. The other hypothesis postulates that it is not high
When the eruption happened my mom remembers seeing a curtain of ash coming towards Spokane. My mom was working at Ihop when everyone was told to leave early so they could get home safely. So my mom went home to check on her family. Luckily she got there before the ash and her whole family was safe. Once the curtain of ash reached her home everything was covered, cars, the house, and basically everything. After that