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Marie Edmonds - One of the best experts on this subject based on the ideXlab platform.
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tephra deposits associated with a large lava dome collapse soufriere hills volcano montserrat 12 15 july 2003
2006Co-Authors: Marie Edmonds, Richard A. Herd, Michael H. StruttAbstract:Abstract The 12–13 July 2003 dome collapse at Soufriere Hills Volcano, Montserrat, was the largest event of its kind during the eruption thus far (1995–2005), involving the removal of 210 million m 3 of the lava dome complex over 18 h. Less than 2% of the total volume of material involved in the dome collapse was deposited on land. A pyroclastic density current deposit alongshore and inland from the Tar River Fan was generated from a single blast originating at the shoreline. The blast was caused by the interaction of pyroclastic flows with seawater. We propose that at the peak of the lava dome collapse, a sharp increase in the volume flux of pyroclastic flows caused substantial displacement of seawater from the shoreline, followed by inrush of seawater when the flux decreased a few minutes later. The tsunami allowed penetration of seawater into the main body of the pyroclastic flow at the shoreline, which led to explosive fragmentation of pyroclastic blocks. Tephra fall deposits accumulated at a high rate on Montserrat, causing extensive damage to vegetation and buildings. Their stratigraphy recorded fallout from high co-pyroclastic flow clouds, from a vulcanian explosion cloud at the peak in collapse rate (caused by the fragmentation of degassed lava dome) and from four vulcanian explosion clouds after the dome collapse (caused by fragmentation of bubbly magma in the conduit). The total tephra fall volume is estimated at 10–20 million m 3 .
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Catastrophic lava dome failure at Soufrière Hills Volcano, Montserrat, 12-13 July 2003
2005Co-Authors: Richard A. Herd, Marie Edmonds, V. BassAbstract:The lava dome collapse of 12–13 July 2003 was the largest of the Soufriere Hills Volcano eruption thus far (1995–2005) and the largest recorded in historical times from any volcano; 210 million m3 of dome material collapsed over 18 h and formed large pyroclastic flows, which reached the sea. The evolution of the collapse can be interpreted with reference to the complex structure of the lava dome, which comprised discrete spines and shear lobes and an apron of talus. Progressive slumping of talus for 10 h at the beginning of the collapse generated low-volume pyroclastic flows. It undermined the massive part of the lava dome and eventually prompted catastrophic failure. From 02:00 to 04:40 13 July 2003 large pyroclastic flows were generated; these reached their largest magnitude at 03:35, when the volume flux of material lost from the lava dome probably approached 16 million m3 over two minutes. The high flux of pyroclastic flows into the sea caused a tsunami and a hydrovolcanic explosion with an associated pyroclastic surge, which flowed inland. A vulcanian explosion occurred during or immediately after the largest pyroclastic flows at 03:35 13 July and four further explosions occurred at progressively longer intervals during 13–15 July 2003. The dome collapse lasted approximately 18 h, but 170 of the total 210 million m3 was removed in only 2.6 h during the most intense stage of the collapse.
Richard A. Herd - One of the best experts on this subject based on the ideXlab platform.
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tephra deposits associated with a large lava dome collapse soufriere hills volcano montserrat 12 15 july 2003
2006Co-Authors: Marie Edmonds, Richard A. Herd, Michael H. StruttAbstract:Abstract The 12–13 July 2003 dome collapse at Soufriere Hills Volcano, Montserrat, was the largest event of its kind during the eruption thus far (1995–2005), involving the removal of 210 million m 3 of the lava dome complex over 18 h. Less than 2% of the total volume of material involved in the dome collapse was deposited on land. A pyroclastic density current deposit alongshore and inland from the Tar River Fan was generated from a single blast originating at the shoreline. The blast was caused by the interaction of pyroclastic flows with seawater. We propose that at the peak of the lava dome collapse, a sharp increase in the volume flux of pyroclastic flows caused substantial displacement of seawater from the shoreline, followed by inrush of seawater when the flux decreased a few minutes later. The tsunami allowed penetration of seawater into the main body of the pyroclastic flow at the shoreline, which led to explosive fragmentation of pyroclastic blocks. Tephra fall deposits accumulated at a high rate on Montserrat, causing extensive damage to vegetation and buildings. Their stratigraphy recorded fallout from high co-pyroclastic flow clouds, from a vulcanian explosion cloud at the peak in collapse rate (caused by the fragmentation of degassed lava dome) and from four vulcanian explosion clouds after the dome collapse (caused by fragmentation of bubbly magma in the conduit). The total tephra fall volume is estimated at 10–20 million m 3 .
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Catastrophic lava dome failure at Soufrière Hills Volcano, Montserrat, 12-13 July 2003
2005Co-Authors: Richard A. Herd, Marie Edmonds, V. BassAbstract:The lava dome collapse of 12–13 July 2003 was the largest of the Soufriere Hills Volcano eruption thus far (1995–2005) and the largest recorded in historical times from any volcano; 210 million m3 of dome material collapsed over 18 h and formed large pyroclastic flows, which reached the sea. The evolution of the collapse can be interpreted with reference to the complex structure of the lava dome, which comprised discrete spines and shear lobes and an apron of talus. Progressive slumping of talus for 10 h at the beginning of the collapse generated low-volume pyroclastic flows. It undermined the massive part of the lava dome and eventually prompted catastrophic failure. From 02:00 to 04:40 13 July 2003 large pyroclastic flows were generated; these reached their largest magnitude at 03:35, when the volume flux of material lost from the lava dome probably approached 16 million m3 over two minutes. The high flux of pyroclastic flows into the sea caused a tsunami and a hydrovolcanic explosion with an associated pyroclastic surge, which flowed inland. A vulcanian explosion occurred during or immediately after the largest pyroclastic flows at 03:35 13 July and four further explosions occurred at progressively longer intervals during 13–15 July 2003. The dome collapse lasted approximately 18 h, but 170 of the total 210 million m3 was removed in only 2.6 h during the most intense stage of the collapse.
V. Bass - One of the best experts on this subject based on the ideXlab platform.
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seismic characterization of pyroclastic flow activity at soufriere hills volcano montserrat 8 january 2007
2007Co-Authors: S. De Angelis, V. Bass, V. Hards, G. RyanAbstract:Abstract. A partial dome collapse with concurrent pyroclastic flow (PF) activity occurred at Soufriere Hills Volcano (SHV), Montserrat on 8 January 2007. Pyroclastic density currents were observed to propagate from the Northwest and West sectors of the summit dome into the heads of Tyres Ghaut and Gages Valley, respectively. Between 10:00 and 10:15 UTC pyroclastic flows entered Tyres Ghaut and from there descended into the Belham Valley reaching a distance of about 5 km from the source. Pyroclastic flow activity on the Northwest and West side of the edifice continued at high levels over the following 1.5 h, although run-out distances of individual flows did not exceed 1.5 km. Subsequent observations showed that material had been removed from the lower Northwest side of the dome leaving an amphitheatre-like structure cutting through the old crater rim. The seismic waves excited by the propagation of pyroclastic flows were recorded by the Montserrat Volcano Observatory's network of broadband seismometers. The seismic records show the onset of a continuous signal before 09:30 UTC with gradually increasing amplitudes and spectral energy in the 1–8 Hz band. The signal rapidly increased in amplitude and a characteristic spindle-shaped waveform with broadband energy (1–25 Hz) was observed accompanying large PF that descended along the slopes of the volcano. The main phase was followed by a sequence of individual seismic pulses which correlated well with visual observations of PF. PF are a major hazard at SHV and pose significant risk for the population living in the proximity of the volcano. They can occur with little or no warning and have the potential to reach inhabited areas to the Northwest. The study of the seismic activity associated with the generation and propagation of pyroclastic flows can help to identify characteristic precursory seismic sequences providing valuable information to improve the understanding of the hazards posed by the SHV and to allow better warning to be given to the authorities.
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Catastrophic lava dome failure at Soufrière Hills Volcano, Montserrat, 12-13 July 2003
2005Co-Authors: Richard A. Herd, Marie Edmonds, V. BassAbstract:The lava dome collapse of 12–13 July 2003 was the largest of the Soufriere Hills Volcano eruption thus far (1995–2005) and the largest recorded in historical times from any volcano; 210 million m3 of dome material collapsed over 18 h and formed large pyroclastic flows, which reached the sea. The evolution of the collapse can be interpreted with reference to the complex structure of the lava dome, which comprised discrete spines and shear lobes and an apron of talus. Progressive slumping of talus for 10 h at the beginning of the collapse generated low-volume pyroclastic flows. It undermined the massive part of the lava dome and eventually prompted catastrophic failure. From 02:00 to 04:40 13 July 2003 large pyroclastic flows were generated; these reached their largest magnitude at 03:35, when the volume flux of material lost from the lava dome probably approached 16 million m3 over two minutes. The high flux of pyroclastic flows into the sea caused a tsunami and a hydrovolcanic explosion with an associated pyroclastic surge, which flowed inland. A vulcanian explosion occurred during or immediately after the largest pyroclastic flows at 03:35 13 July and four further explosions occurred at progressively longer intervals during 13–15 July 2003. The dome collapse lasted approximately 18 h, but 170 of the total 210 million m3 was removed in only 2.6 h during the most intense stage of the collapse.
Michael H. Strutt - One of the best experts on this subject based on the ideXlab platform.
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tephra deposits associated with a large lava dome collapse soufriere hills volcano montserrat 12 15 july 2003
2006Co-Authors: Marie Edmonds, Richard A. Herd, Michael H. StruttAbstract:Abstract The 12–13 July 2003 dome collapse at Soufriere Hills Volcano, Montserrat, was the largest event of its kind during the eruption thus far (1995–2005), involving the removal of 210 million m 3 of the lava dome complex over 18 h. Less than 2% of the total volume of material involved in the dome collapse was deposited on land. A pyroclastic density current deposit alongshore and inland from the Tar River Fan was generated from a single blast originating at the shoreline. The blast was caused by the interaction of pyroclastic flows with seawater. We propose that at the peak of the lava dome collapse, a sharp increase in the volume flux of pyroclastic flows caused substantial displacement of seawater from the shoreline, followed by inrush of seawater when the flux decreased a few minutes later. The tsunami allowed penetration of seawater into the main body of the pyroclastic flow at the shoreline, which led to explosive fragmentation of pyroclastic blocks. Tephra fall deposits accumulated at a high rate on Montserrat, causing extensive damage to vegetation and buildings. Their stratigraphy recorded fallout from high co-pyroclastic flow clouds, from a vulcanian explosion cloud at the peak in collapse rate (caused by the fragmentation of degassed lava dome) and from four vulcanian explosion clouds after the dome collapse (caused by fragmentation of bubbly magma in the conduit). The total tephra fall volume is estimated at 10–20 million m 3 .
John Stevenson - One of the best experts on this subject based on the ideXlab platform.
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particle sizes of andesitic ash fallout from vertical eruptions and co pyroclastic flow clouds volcan de colima mexico
2009Co-Authors: Jason R Evans, Jacqueline E Huntoon, William I Rose, Nick Varley, John StevensonAbstract:We report particle-size distributions for andesitic ash fall from vertical eruptions and clouds above block-and-ash fl ows at Volcan de Colima, Mexico, during 2004‐2006. We analyzed 17 samples using laser diffraction: 11 from vertical eruptions and 6 from block-and-ash fl ows (copyroclastic fl ow ash). Vertical eruptions produce well-sorted fall deposits, whereas co-pyroclastic fall deposits are poorly sorted, with high proportions of very fi ne grained ash (<30 µm). Statistical analysis shows particle-size distributions of vertical eruptions are more leptokurtic (peaked) than co-pyroclastic samples. Deconvolution of grain-size histograms shows that copyroclastic samples have at least one subpopulation with a mode of 8.3‐8.7 φ (2.4‐3.1 µm). Estimates of the number of particles in different size ranges show that co-pyroclastic samples contain much greater numbers of very fi ne particles than vertical eruption samples. Our results provide no direct evidence that milling or comminution produces hazardous fi ne ash particles in pyroclastic fl ows, but are consistent with that interpretation.
