pyroclastic

adjective

py·​ro·​clas·​tic ˌpī-rō-ˈkla-stik 

: formed by or involving fragmentation as a result of volcanic or igneous action

Examples of pyroclastic in a Sentence

Recent Examples on the Web

The eruption triggered tsunamis and pyroclastic flows — fast-moving lava that flows down the volcano — and initially killed around 10,000 people. —Monica Cull, Discover Magazine, 2 Jan. 2025

Their death provides some of the strongest evidence yet found that quakes presented another deadly obstacle—in addition to hot ash, pumice, and pyroclastic flows—for Pompeiians. Andrew Curry’s story later in the year shed light on the relationships between these unfortunate souls. —Christie Wilcox, science.org, 27 Dec. 2024

The Philippines' Institute of Volcanology and Seismology reported that the eruption triggered a pyroclastic density current—a scorching flow of ash, debris, and rocks capable of obliterating everything in its path. —Paul Du Quenoy, Newsweek, 10 Dec. 2024

But after the eruption buried the trilobites, cool seawater mixed with the hot ash and quickly hardened the pyroclastic flow into a tomb of solid rock. —Mindy Weisberger, CNN, 9 July 2024

Word History

Etymology

probably from pyro- + clastic

Note: The term was introduced by the English geologist Joseph Beete Jukes (1811-69) in The Student's Manual of Geology, new edition (Edinburgh, 1862), p. 68: "The word 'ash' is not a very good one to include all the mechanical accompaniments of a subaerial or subaqueous eruption, since ash seems to be restricted to a fine powder, the residuum of combustion. A word is wanting to express all such accompaniments, no matter what their size or condition may be, when they are accumulated in such mass so as to form beds of 'rock.' We might call them perhaps 'pyroclastic materials'…." In the index pyroclastic is glossed as "broken from fire."

First Known Use

1862, in the meaning defined above