- ALASKA VOLCANO OBSERVATORY GLOSSARY
A low-density, turbulent flow of fine-grained volcanic rock debris and hot gas. Pyroclastic surges differ from pyroclastic flows in that they are less dense and tend to travel as a low, ground-hugging, but highly mobile cloud that an surmount topographic barriers. Surges often affect areas beyond the limits of pyroclastic flows.\GLOSSARY OF VOLCANIC TERMSA type of turbulent, low density (low particle concentration) pyroclastic cloud or pyroclastic density current. Being more dilute than pyroclastic flows, surges can sweep over ridges, hills, and other topographic boundaries. Two kinds of surges are known: wet surges have temperatures < 100°C and contain steam that condenses into water droplets that surge along the ground surface with gas and pyroclasts; and dry surges, which have temperatures >100°C, and form by either hydrovolcanic eruptions with low water/magma ratios, or by magmatic eruptions driven solely by expanding magmatic gases (Valentine and Fisher, 2000, p. 571).
Glossary of volcanic terms. - University of Wisconsin Oshkosh. G. J. Hudak. 2001.
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Pyroclastic surge — A pyroclastic surge is a fluidized mass of turbulent gas and rock fragments which is ejected during some volcanic eruptions. It is similar to a pyroclastic flow but contains a much higher proportion of gas to rock, which makes it more turbulent… … Wikipedia
pyroclastic surge — A low density, dilute, turbulent pyroclastic flow, usually very hot, composed of a generally unsorted mixture of gases and comparatively low concentrations of pyroclastic particles (ash, pumice, and dense rock fragments) that travels across… … Glossary of landform and geologic terms
pyroclastic surge — noun a fluidized mass of turbulent gas and rock fragments which is ejected during some volcanic eruptions … Wiktionary
pyroclastic surge deposit — GLOSSARY OF VOLCANIC TERMS Pyroclastic deposits that are left by pyroclastic surges. These deposits mantle topographic features but also generally thicken within topographic depressions. These deposits are generally well sorted, and are enriched… … Glossary of volcanic terms
Pyroclastic flow — Pyroclastic flows sweep down the flanks of Mayon Volcano, Philippines, in 1984 … Wikipedia
Pyroclastic rock — Pyroclastic rocks or pyroclastics (derived from the Greek πῦρ , meaning fire, and κλαστός , meaning broken) are clastic rocks composed solely or primarily of volcanic materials. Where the volcanic material has been transported and reworked… … Wikipedia
Surge — may refer to: *Surge (soft drink), a soft drink formerly made by The Coca Cola Company. *Jerk or surge, the rate of change of acceleration in physics *Storm surge, the onshore gush of water associated with a low pressure weather system… … Wikipedia
Surge — Der Begriff Surge (engl. surge = Welle, Woge), z.T. auch Base Surge oder Ground Surge, wird in der Sedimentologie als Überbegriff für relativ partikelarme, turbulente, oft auch heiße Ströme eines Gas (Flüssigkeit) Partikelgemisches, d.h. für… … Deutsch Wikipedia
Pyroclastic fall — A pyroclastic fall is a uniform deposit of material which has been ejected from an eruption or plume such as an ash fall or tuff. Pyroclastic flows occur relatively spontaneously in the geological time scale and are great indicators of time.… … Wikipedia
pyroclastic flow — A fast density current of pyroclastic material, usually very hot, composed of a mixture of gasses and a high concentration of pyroclastic particles in a variety of sizes and composition (ash, pumice, scoria, lava fragments, etc.); produced by… … Glossary of landform and geologic terms