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Pyroclastic flows sweep down the flanks of Mayon Volcano, Philippines, in 2018. A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) [1] is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of 100 km/h (30 m/s; 60 mph) but is capable of reaching speeds up to ...
In addition to their observations, the Kraffts also took measures, gas readings, and samples, often feet away from pyroclastic and lava flows, and documented how the eruptions affected the local ecosystem. [10] The Kraffts documented the formation of new volcanoes, in addition to the effects of acid rain and ash clouds. [11]
The resulting deposits formed a fan-like pattern of overlapping sheets, tongues, and lobes. At least 17 separate pyroclastic flows occurred during the May 18 eruption, and their aggregate volume was about 0.05 cu mi (0.21 km 3). [9] The flow deposits were still at about 570 to 790 °F (300 to 420 °C) two weeks after they erupted. [9]
Pyroclasts are transported in two main ways: in atmospheric eruption plumes, from which pyroclasts settle to form topography-draping pyroclastic fall layers, and by pyroclastic density currents (PDCs) (including pyroclastic flows and pyroclastic surges), [6] from which pyroclasts are deposited as pyroclastic density current deposits, which tend ...
[33]: 69 A pyroclastic flow from South Deadman vent traveled about 3.7 miles (6 km). [34] Some of the open pits were filled with thick and slow-moving lava to form the South Deadman Creek, Glass Creek and Obsidian Flow domes. [36] Others, such as the Inyo Crater Lakes near Deer Mountain, remained open and were later partially filled with water.
As the pyroclastic flow reached Onokoba the pyroclastic surge detached from the main flow body as it continued moving 600 m (2,000 ft) to the SE before losing its energy and stopping. The surge was powerful enough to move a car 120 m (390 ft), flatten and uproot large trees and even move large debris in Kita-Kamikoba and Onokoba.
The Bishop Tuff is a welded tuff which formed 764,800 ± 600 years ago as a rhyolitic pyroclastic flow during the approximately six-day eruption that formed the Long Valley Caldera. [1] [2] [3] Large outcrops of the tuff are located in Inyo and Mono Counties, California, United States. Approximately 200 cubic kilometers of ash and tuff erupted ...
Jan Mayen is made up of basalt flows and pyroclastic flow related mafic deposits. The two most recent eruptions were in 1970 and 1985, although the Central Crater and Egg Island craters on the southern side of the mountain have continuous fumarole activity. [1]