GEOL 110 Study Guide - Midterm Guide: Stratovolcano, Soil Horizon, Lake Nyos
Document Summary
St. helens is now safe because the volcano is finished erupting and will stay dormant for the next 200 years. Caldera eruptions can involve the largest volcanic eruptions on earth and they are the rarest. Caves form in places where giant bubbles were present in the lava that formed the earth"s crust. Composite volcanoes can have a long dormant period in which people can forget that they were ever once active volcanoes. Damage from soil volume change in the u. s. commonly costs more annually than all other natural disasters combined. The disaster at lake nyos in cameroon (africa) is thought to have been caused by a suffocating cloud of carbon dioxide gas. Rivers can flood after rain has stopped and tributaries have flowed into bigger streams. People do not increase or decrease the volcanic hazard. Earthquakes cause subsidence because tectonic plates involved in subduction can actually snap downward after stress is released in an earthquake.
