A magma reservoir in the shallow crust beneath Santorini Volcano in Greece may be a short-lived feature, reports a study published online this week in Nature Geoscience. The findings suggest that eruptions at Santorini are triggered by the rapid injection of large volumes of magma into the shallow crust.

David Pyle and colleagues used satellite and land-survey data to assess changes in the volume of the subsurface magma chamber since the volcano’s last eruption in the 1950s. They show that the chamber volume remained relatively stable until January 2011, when between 10 and 20 million metres cubed of magma were added to the reservoir, causing the volcano to inflate. Previously, such shallow magma reservoirs were thought to be long-lived features that were continually fed small batches of magma from below.

In an accompanying News and Views article, Andrew Hooper says: “The new observations from Santorini do not preclude the existence of a permanent shallow magma body. They do, however, suggest that most of the magma that goes on to erupt is transferred to shallow depths in short pulses.”