Phreatomagmatic eruption
（重定向自Tuff cone）
![Ashfall deposit of phreatomagmatic origin, overlying magmatic lapilli fall deposit of magmatic origin.](/Images/godic/202502/18/Ash_and_lap_fall4610.JPG")
![Crest of old tuff ring, including part of the maar crater of a monogenetic volcano, Tenerife, Canary Islands. The maar crater has been used for agriculture.](/Images/godic/202502/18/Tuff_ring4610.JPG")
![Koko Crater is an old extinct tuff cone in the Hawaiian Island of Oahu.](/Images/godic/202502/18/Koko_Crater4610.jpg")
![Fort Rock, an eroded tuff ring in Oregon, USA.](/Images/godic/202502/18/Fortrock4610.jpg")
Phreatomagmatic eruptions are defined as juvenile forming eruptions as a result of interaction between water and magma. They are different from magmatic and phreatic eruptions. The products of phreatomagmatic eruptions contain juvenile clasts, unlike phreatic eruptions, and are the result of interaction between magma and water, unlike magmatic eruptions. It is very common for a large explosive eruption to have magmatic and phreatomagmatic components.