1
: of, relating to, or being groundwater
2
: of, relating to, or being an explosion caused by steam derived from groundwater

Examples of phreatic in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Poás is what is called a phreatic volcano, which has a deep magma chamber, well away from sight, and when water trickles down into it, pressure builds up dangerously deep underneath the crater, like a mountain-sized pressure cooker. — Literary Hub, 16 May 2025 In that case, the ongoing seismic activity could stop abruptly or peak in a phreatic eruption—the volcano would spurt out hot liquids, gases and rock fragments instead of lava. — Alessio Perrone, Scientific American, 4 Dec. 2023 Its eruptions range from phreatic (steam-driven) to Plinian—extremely explosive eruptions that can send volcanic debris tens of miles into the Earth’s atmosphere. — Time, 15 June 2023 This all could mean that new magma is moving under Taal and this phreatic blast is just another sign that Taal is heading towards a potential new period of activity or larger explosions. — Erik Klemetti, Discover Magazine, 12 Jan. 2020 Now, this explosion may be a one-off at Kusatsu as many phreatic eruptions are. — Erik Klemetti, Discover Magazine, 23 Jan. 2018 In fact, the eruption on Ontake in Japan that killed over 40 people in 2014 was also a phreatic explosion with little in the way of earthquakes or other signs an eruption could happen. — Erik Klemetti, Discover Magazine, 23 Jan. 2018 Ontake has a limited history of phreatic explosions but so do most volcanoes in settings like Japan (or the Cascades for that matter). — Erik Klemetti, Discover Magazine, 28 Sep. 2014

Word History

Etymology

Greek phreat-, phrear well; akin to Armenian ałbiwr spring, Old High German brunno — more at burn

First Known Use

circa 1890, in the meaning defined at sense 1

Time Traveler
The first known use of phreatic was circa 1890

Browse Nearby Words

Cite this Entry

“Phreatic.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/phreatic. Accessed 6 Oct. 2026.

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