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A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. [1] Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit ...
April 23, 2024 at 12:07 PM. When Mount Ruang in Indonesia underwent multiple explosive eruptions last week, volcanic gases were flung so high they reached the atmosphere’s second layer, tens of ...
Types of volcanic eruptions. Some of the eruptive structures formed during volcanic activity (counterclockwise): a Plinian eruption column, Hawaiian pahoehoe flows, and a lava arc from a Strombolian eruption. Several types of volcanic eruptions —during which material is expelled from a volcanic vent or fissure —have been distinguished by ...
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. The process that forms volcanoes is called volcanism. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and because most of Earth ...
Volcanic hazard. A schematic diagram shows some of the many ways volcanoes can cause problems for those nearby. A volcanic hazard is the probability a volcanic eruption or related geophysical event will occur in a given geographic area and within a specified window of time. The risk that can be associated with a volcanic hazard depends on the ...
Volcanic gas. Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic craters or vents.
Mount Pinatubo[ 4 ] is an active stratovolcano in the Zambales Mountains in Luzon in the Philippines. Located on the tripoint of Zambales, Tarlac and Pampanga provinces, [ 5 ][ 6 ] most people were unaware of its eruptive history before the pre-eruption volcanic activity in early 1991.
The volcanic explosivity index (VEI) is a relative measure/prediction of the explosiveness of volcanic eruptions. It was devised by Christopher G. Newhall of the United States Geological Survey and Stephen Self in 1982. Volume of products, eruption cloud height, and qualitative observations (using terms ranging from "gentle" to "mega-colossal ...