Block and ash flow
A block and ash flow or block-and-ash flow is a flow of a mixture of volcanic ash and large (>26 cm) angular blocks.[1] It commonly is formed as result of pyroclastic flow during a volcanic eruption. Collapse of lava domes are known to result in block and ash flow.[2] In differnece to other types of pyroclastic flows block and ash fows do no contain pumice.[3] Block and ash flows result in the formation of block and ash flow deposits which may under some definitions qualify as a type of ignimbrite.[4]
Some volcanoes known for their production of block and ash flows in the last decades are Mount Unzen in Japan, Mount Merapi in Java and Soufrière Hills in the lesser Antilles.[4]
References
- ^ "Glossary - Block and ash flow". volcanoes.usgs.gov. United States Geological Survey. Retrieved 22 October 2018.
Flow of ash and angular rock fragments larger than 26 cm or 10 in.
- ^ Tahide, Ui; Matsuwo, Norimichi; Sumita, Marit; Fujinawa, Akihiko (1999). "Generation of block and ash flows during the 1990–1995 eruption of Unzen Volcano, Japan". Journal of Volcanology and Geothermal Research. 89 (1–4): 123–137. doi:10.1016/S0377-0273(98)00128-0. Retrieved October 22, 2018.
- ^ "Block-and-ash flow deposit or lithic breccia?". Sandsatlas. Retrieved October 22, 2018.
- ^ a b "Block-and-ash flow deposits". Sandsatlas. Retrieved October 22, 2018.