Geologists are reporting the ground at the Campi Flegrei caldera, near Naples, Italy, is undergoing renewed uplift.
Researchers at Italy's Geophysical National Institute and Volcanology Observatory report the volcanic area, which had its last eruption in 1538, started a new uplift episode in November 2004. That uplift began at a low rate but has slowly and steadily increased.
According to previous studies, the 16th-century eruption occurred after decades of uplift coupled with brief periods of subsidence. Within the past 40 years, the caldera experienced a huge uplift phase until 1985. The new data indicate a subsequent period of subsidence has now ended.
Scientists say the ratio of maximum horizontal to vertical displacement, determined from Global Positioning System data, suggests the uplift is associated with input of magma from a shallow chamber.
The research appears in the journal Geophysical Research Letters.
Copyright 2007 by United Press International
Explore further: Satellite imagery detects thermal 'uplift' signal of underground nuclear tests