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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 volcanologists.
A volcanologist is a geologist who studies the eruptive activity and formation of volcanoes and their current and historic eruptions. Volcanologists frequently visit volcanoes, especially active ones, to observe volcanic eruptions, collect eruptive products including tephra (such as ash or pumice), rock and lava samples. One major focus of ...
The term composite volcano is used because strata are usually mixed and uneven instead of neat layers. [6] They are among the most common types of volcanoes; [7] more than 700 stratovolcanoes have erupted lava during the Holocene Epoch (the last 11,700 years), [8] and many older, now extinct, stratovolcanoes erupted lava as far back as Archean ...
The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a volcanic edifice, typically a volcanic cone or mountain. [2] [22] The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; however, this describes just one of the many types of ...
A volcanic eruption could just be a simple outpouring of material onto the surface of a planet, but they usually involve a complex mixture of solids, liquids and gases which behave in equally complex ways. [3] Some types of explosive eruptions can release energy a quarter that of an equivalent mass of TNT. [18]
These are characterized by plateau landforms, so that flood basalts are also described as plateau basalts. Canyons cut into the flood basalts by erosion display stair-like slopes, with the lower parts of flows forming cliffs and the upper part of flows or interbedded layers of sediments forming slopes.
A volcanic eruption is effusive when the erupting magma is volatile poor (water, carbon dioxide, sulfur dioxide, hydrogen chloride, and hydrogen fluoride), which suppresses fragmentation, creating an oozing magma which spills out of the volcanic vent and out into the surrounding area. [1]
The massive eruptive event that formed the traps is one of the largest known volcanic events in the last 500 million years. The eruptions continued for roughly two million years and spanned the Permian – Triassic boundary, or P–T boundary, which occurred around 251.9 million years ago.