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The ash and tephra are ejected at speeds of several hundred metres per second, and can rise rapidly to heights of several kilometres, lifted by enormous convection currents. Eruption columns may be transient, if formed by a discrete explosion, or sustained, if produced by a continuous eruption or closely spaced discrete explosions.
Peru's government declared a 60-day state of emergency for several southern towns on Wednesday as the country's most active volcano spews ash and gas. Ash from the Ubinas volcano in the Moquegua ...
Indonesia has evacuated about 6,500 people on the island of Flores after Mount Lewotobi Laki-laki volcano spewed thick clouds of brownish ash for the past days, authorities said on Monday. The ...
7 January 2015: CENAPRED reported that ash from recent explosions coated the snow on the volcano's upper slopes. [30] 28 March 2016: An ash column 2,000 m (6,600 ft) high was released, prompting the establishment of a 12-kilometre (7.5 mi) "security ring" around the summit. [31] 3 April 2016: Popocatépetl erupted, spewing lava, ash and rock. [32]
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 ...
A significant explosion at 1:09 a.m. Friday produced an ash cloud that reached up to 40,000 feet (12,192 meters) and drifted south over the Pacific Ocean. Alaska volcano spews ash cloud high ...
Ash plume 2. Lapilli 3. Volcanic ash rain 4. Lava fountain 5. Volcanic bomb 6. Lava flow 7. Layers of lava and ash 8. Stratum 9. Dike 10. Magma conduit 11. Magma chamber 12. Sill) Click for larger version. Strombolian eruptions are a type of volcanic eruption named after the volcano Stromboli, which has been erupting nearly continuously for ...
Tephrochronology is a geochronological technique that uses discrete layers of tephra—volcanic ash from a single eruption—to create a chronological framework in which paleoenvironmental or archaeological records can be placed. Often, when a volcano explodes, biological organisms are killed and their remains are buried within the tephra layer.