which types of lava eruptions cover the largest area on Earth's surface?
http://en.wikipedia.org/wiki/Flood_basalt
is it flood basalt
To determine which types of lava eruptions cover the largest area on Earth's surface, we need to understand the different types of lava and their characteristic behaviors.
Lava is molten rock that flows from a volcano during an eruption. There are two main types of lava: effusive lava and explosive lava.
1. Effusive lava eruptions: These eruptions involve the relatively gentle flow of lava onto the Earth's surface. The two main types of effusive lava are:
- Basaltic lava: This type of lava is low in viscosity, which means it flows easily. Basaltic lava eruptions can cover large distances, forming extensive lava fields. They often result in the creation of shield volcanoes, which are broad and gently sloping volcanoes with large surface areas. Examples include the eruptions on the Hawaiian Islands and the Columbia River Basalt Group in the United States.
- Flood basalt eruptions: These are some of the largest volcanic eruptions on Earth. They occur when massive volumes of basaltic lava are released from fractures in the Earth's crust over a short period of time. Flood basalt eruptions, also known as flood basalts, can cover vast areas, often hundreds of thousands of square kilometers. Examples include the Deccan Traps in India and the Siberian Traps in Russia.
2. Explosive lava eruptions: These eruptions involve the fragmentation of magma into pyroclastic material, which is a hot mixture of gas, ash, and rock fragments. The two main types of explosive lava are:
- Rhyolitic lava: This type of lava has high viscosity, meaning it is sticky and does not flow easily. Rhyolitic lava eruptions tend to be explosive and violent, releasing large amounts of pyroclastic material. However, due to its high viscosity, the lava doesn't cover large areas but forms volcanic domes or plugs near the vent. Examples of rhyolitic eruptions include the 1980 eruption of Mount St. Helens in the United States and the eruption of Mount Pinatubo in the Philippines in 1991.
- Andesitic or dacitic lava: These lavas have intermediate viscosities between basaltic and rhyolitic lavas. They can erupt explosively or effusively, depending on the specific conditions. Andesitic or dacitic lava eruptions can exhibit both explosive eruption styles, with pyroclastic flows and ashfall covering significant distances, as well as the formation of lava flows. Examples include the eruptions of Mount Vesuvius in Italy and Mount Mayon in the Philippines.
In summary, effusive lava eruptions, specifically basaltic lava eruptions and flood basalt eruptions, cover the largest areas on Earth's surface due to their low viscosity and ability to flow easily over a long distance.