Collapse of Volcanic Dome Led to Montserrat Eruption That Killed 9

Scientists say the eruption that killed at least nine people last week on the tiny 12-by-8-mile Caribbean island of Montserrat (see map above) was the consequence of the collapse of a volcanic dome that sent pyroclastic materials flowing at 200 miles per hour into neighborhoods that had been previously untouched.

Still, a report by the Montserrat Volcano Observatory said that all those killed, as well as 19 people who are missing, were in areas that had been ordered evacuated well in advance of the June 25 event.

Pyroclastic flows are a mixture of rocks, air, gases and ash superheated to 1,000 degrees. The report detailed on a minute-by-minute basis instrumental reports showing inflation of magma within the Soufriere Hills volcano just before the largest flow began, and then sudden deflation as the material was expelled.