PRESENTATION OUTLINE
what is a volcano?
a mountain or hill, typically conical, having a crater or vent through which lava, rock fragments, hot vapor, and gas are being or have been erupted from the earth's crust.
how the volcanoes form?
Volcanoes are formed when magma from within the Earth's upper mantle works its way to the surface. At the surface, it erupts to form lava flows and ash deposits. Over time as the volcano continues to erupt, it will get bigger and bigger.
shield volcanoes,cinder cones and composite cones.
what is a shield volcano?
a broad, domed volcano with gently sloping sides, characteristic of the eruption of fluid, basaltic lava.
what is a cinder cone volcano?
cinder cones are small volcanoes built primarily of pyroclastic material ejected from a single vent.
what is a composite cone volcano?
composite cones are volcanoes composed of both lava flows and pyroclastic material. Most are adjacent to the pacific ocean
The Significant Volcanic Eruption is a global listing of over 500 significant eruptions which includes information on the latitude, longitude, elevation, type of volcano, and last known eruption. A significant eruption is classified as one that meets at least one of the following criteria: caused fatalities, caused moderate damage (approximately $1 million or more), with a Volcanic Explosivity Index (VEI) of 6 or larger, caused a tsunami, or was associated with a major earthquake.
why the volcano erupt?Volcanoes erupt because of density and pressure. The lower density of the magma relative to the surrounding rocks causes it to rise (like air bubbles in syrup). It will rise to the surface or to a depth that is determined by the density of the magma and the weight of the rocks above it.
active volcanoes today
- Eyjafjallajökull, Iceland.
- sakurajima, japan.
- mauna loa, hawaii.
- galeras, colombia.
- santa maria, guatemala.
the largest volcanic eruption ever occurred on Earth.
in 1980, Mount St. Helens erupted with an energy equivalent of a Hiroshima bomb every second and expelled 1.2 km³ of lava and pyroclastic material