1985年11月13日 · Pyroclastic flows are avalanches of hot fragments and gas down the slopes of volcanoes, typically at 20–50 m s − 1. The terminology of pyroclastic flows is complicated, reflecting multiple origins of flows (Wright et al., 1980). Most pyroclastic flows form by collapse of an eruption column, collapse of a dense slug of debris erupted just a ...

2015年1月1日 · Pyroclastic density currents (PDCs) or pyroclastic flows and surges as end-member types, are probably the most destructive and complex volcanic phenomena with respect to the dynamics of flow (Sigurdsson et al., 1987, Druitt, 1998, Branney and Kokelaar, 2002). They have also been the most difficult to observe directly, due to the extreme hazard ...

2013年3月16日 · Pyroclastic materials, also called tephra, are formed from cooling magma during explosive volcanic eruptions. They present widely varying physical properties and can range in size from sub-millimetric ash up to boulder size (Brown and Calder, 2005). Pyroclastic materials can have a dense (volcanic tuffs) or a vesicular structure (volcanic ...

2014年8月15日 · Pyroclastic density currents (PDCs) are mixtures of two components, namely solid particles and fluid (gas) phase. They macroscopically behave as dense, multiphase gravity currents (flowing pyroclastic mixtures of particles and gas) immersed in a less dense, almost isotropic fluid (the atmosphere).

2024年11月1日 · A variety of deposits related to pyroclastic materials, including pyroclastic fall and pyroclastic density currents, are also characterised by lahars, lava flows, tsunami deposits, debris avalanches, lava domes (of the hummocky variety, as observed at Mount Shasta (Crandell et al., 1984). The aim of this study was to ascertain whether the ...

2022年7月1日 · Because pyroclastic lava and sedimentary pyroclastic rocks are often found in pyroclastic reservoirs, this classification scheme is a better match for the pyroclastic rocks in China (Chen et al., 2018; Niu et al., 2019; Zeng et al., 2021a).

2024年4月15日 · Pyroclastic flows are mixtures of gas and particles generated by gravitational collapse of lava domes or fall-back of eruption columns during explosive eruptions. They are major natural hazards because they can propagate far away from the source at speeds that largely exceed those of most natural or anthropogenic granular flows.

Pyroclastic flows can flow over ridges as much as a kilometer in height (Bryant, 1991). More people have died due to these hazards than any other volcanic hazard. Pyroclastic flows can incinerate, burn, and asphyxiate people. Pyroclastic flows travel long …

2024年4月1日 · Locations of pyroclastic samples obtained by piston coring (PC-1 to PC-4) and ROV (KC-1 to KC-3) are indicated by green and yellow stars, respectively. Bathymetry around the Kikai caldera was obtained by our survey; the other bathymetry and on-land topography are drawn by using 500-m mesh J-EGG and EarthEnv-DEM90 ( Robinson et al., 2014 ...

2022年7月1日 · The three cementation modes dictate the three classes of pyroclastic rock: pyroclastic lava, normal pyroclastic rock, and sedimentary pyroclastic rock. Within these three modes, pyroclastic rocks are further classified by their clastic material grain size into agglomerate, breccia, and tuff. If the pyroclastic material is moved by aeolian ...