It's worse than that...
Ed Drobyshevski, chief author of that Tunguska study, has worked on his "Explosive Cosmogony" for nearly 30 years. His basic conclusion is that solid-state electrolysis can cause the breakdown of water into H2/O2, slowly building up to an explosive level. A sufficient input of energy - like an asteroid strike - can spark the spontaneous combustion of the upper crust of ice moons like Europa, Ganymede or Callisto, resulting in a massive pulse of ~ 1 km wide cometoids that would shower the Inner Planets for years afterwards. Imagine a Tunguska a day, or worse, for years...