caa a22 4500 477062202 CHVBK 20180405111404.0 cr unu---uuuuu 170330e19960401xx s 000 0 eng 10.1007/BF00304435 doi (NATIONALLICENCE)springer-10.1007/BF00304435 Pyroclastic flows and surges over water: an example from the 1883 Krakatau eruption [Elektronische Daten] [S. Carey, H. Sigurdsson, C. Mandeville, S. Bronto] Pyroclastic deposits from the 1883 eruption of Krakatau are described from areas northeast of the volcano on the islands of Sebesi, Sebuku, and Lagoendi, and the southeast coast of Sumatra. Massive and poorly stratified units formed predominantly from pyroclastic flows and surges that traveled over the sea for distances up to 80 km. Granulometric and lithologic characteristics of the deposits indicate that they represent the complement of proximal subaerial and submarine pyroclastic flow deposits laid down on and close to the Krakatau islands. The distal deposits exhibit a decrease in sorting coefficient, median grain size, and thickness with increasing distance from Krakatau. Crystal fractionation is consistent with the distal facies being derived from the upper part of gravitationally segregated pyroclastic flows in which the relative amount of crystal enrichment and abundance of dense lithic clasts diminished upwards. The deposits are correlated to a major pyroclastic flow phase that occurred on the morning of 27 August at approximately 10 a.m. Energetic flows spread out away from the volcano at speeds in excess of 100 km/h and traveled up to 80 km from source. The flows retained temperatures high enough to burn victims on the SW coast of Sumatra. Historical accounts from ships in the Sunda Straits constrain the area affected by the flows to a minimum of 4x103 km2. At the distal edge of this area the flows were relatively dilute and turbulent, yet carried enough material to deposit several tens of centimeters of tephra. The great mobility of the Krakatau flows from the 10 a.m. activity may be the result of enhanced runout over the sea. It is proposed that the generation of steam at the flow/seawater interface may have led to a reduction in the sedimentation of particles and consequently a delay in the time before the flows ceased lateral motion and became buoyantly convective. The buoyant distal edge of these ash-and steam-laden clouds lifted off into the atmosphere, leading to cooling, condensation, and mud rain. Springer-Verlag, 1996 Krakatau nationallicence Pyroclastic flows nationallicence Pyroclastic surge nationallicence Tsunamis nationallicence Volcanic hazard nationallicence Explosive eruption nationallicence Carey S. Graduate School of Oceanography, University of Rhode Island, 02882, Narragansett, RI, USA aut Sigurdsson H. Graduate School of Oceanography, University of Rhode Island, 02882, Narragansett, RI, USA aut Mandeville C. Graduate School of Oceanography, University of Rhode Island, 02882, Narragansett, RI, USA aut Bronto S. Volcanological Survey of Indonesia, Bandung, Indonesia aut Bulletin of Volcanology Springer-Verlag 57/7(1996-04-01), 493-511 0258-8900 57:7<493 1996 57 445 https://doi.org/10.1007/BF00304435 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00304435 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Carey S. Graduate School of Oceanography, University of Rhode Island, 02882, Narragansett, RI, USA aut NATIONALLICENCE 700 1- Sigurdsson H. Graduate School of Oceanography, University of Rhode Island, 02882, Narragansett, RI, USA aut NATIONALLICENCE 700 1- Mandeville C. Graduate School of Oceanography, University of Rhode Island, 02882, Narragansett, RI, USA aut NATIONALLICENCE 700 1- Bronto S. Volcanological Survey of Indonesia, Bandung, Indonesia aut NATIONALLICENCE 773 0- Bulletin of Volcanology Springer-Verlag 57/7(1996-04-01), 493-511 0258-8900 57:7<493 1996 57 445 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer