Hydrothermal Explosion at Yellowstone Sends Tourists Racing for Safety The New York TimesHydrothermal explosion leads to closure of parts of Yellowstone National Park CNNYellowstone eruption blasts debris into sky near Old Faithful geyser BBC.comSurprise blast of rock, water and steam sends dozens running for safety in Yellowstone Montana Free PressYellowstone Park Officials Conclude Cause Of Explosion The Weather Channel