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These events are not directly related to the eruption itself but are triggered by it. These could range from anything from fires to floods depending on the type of eruption to more damaging natural processes. The most devastating of all of the secondary effects result in the mass wasting (or rapid downhill movement) of materials. There’s a potential for lahars which are mudflows caused by the mixing of water, either by rain or melted snow and volcanic ash on the sides of volcanoes. Sometimes these occur long after volcanic eruptions. There can also be debris avalanches which occur when many different materials are mixed together. In the instance of the 1980 Mount Saint Helen’s eruption, a debris avalanche occurred as a result of more than 10 million uprooted trees mixing with ash and mud. Newhall states “As the ash blew eastward, great slurries of mud and trees bore down rivers to the west. The Columbia River channel filled with so much sediment that shipping had to be halted until a new channel could be dredged” (1181). This resulted in widespread …show more content…
There is often a drastic change to the landscape whether it’s from the changing face of a volcano due to eruption, the scarring of the land by lava, mudflows or debris avalanches or even by the addition of land that’s sometimes formed as a result of eruption. This was the case for Surtsey, an Icelandic island formed as a result of undersea volcanic activity over the span of 3.5 years (Schipper et al. 11498). There are sometimes even global ramifications for an eruption. For example, the Mt. Pinatubo eruption of 1991 resulted in a change in global temperature, cooling it for about a year. The sulfur dioxide emitted into the air from the eruption transformed into sulfate aerosols and According to Thomas et al. “Sulfate aerosol particles are purely scattering in the visible part of the solar spectrum, thus scattering the incoming solar radiation partially back to space, resulting in cooling of the Earth surface” (757). Another long term effect of volcanic activity is fertile soils. These fertile grounds have attracted many a farmer to the lands shadowed by often hazardous volcanoes. In the area around Indonesia’s Mt Merapi, a volcano with a rich history of eruption, there are several farming villages that have popped up to utilize the fertile Earth. Merck states “Although volcanic soils cover just 1% of Earth’s land surface, they support 10% of the world’s population”