AGU Journal Highlights -- February 23, 2007

1. Ground rising again at volcano near Naples, Italy

Ground deformation data indicates that the Campi Flegrei caldera, near Naples, Italy, is undergoing renewed uplift. Troise et al. report that the volcanic area, which had its last eruption in 1538, started a new uplift episode in November 2004. This uplift began at a low rate, but has since 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 that a subsequent period of subsidence has now ended. The ratio of maximum horizontal to vertical displacement, determined from Global Positioning System data, suggests that the uplift is associated with input of magma from a shallow chamber, the authors conjecture. They expect that future uses of this displacement method will help scientists monitor magma intrusion processes at this and other volcanoes and thus help quantify volcanic hazards.

Title: Renewed ground uplift at Campi Flegrei caldera (Italy): New insight on magmatic processes and forecast.

Authors: C. Troise, G. De Natale, F. Pingue, F. Obrizzo, P. De Martino, U. Tammaro, and E. Boschi: Instituto Nazionale de Geofisica e Vulcanologia-Osservatario Vesuviano, Naples, Italy.

Source: Geophysical Research Letters (GRL) paper 10.1029/2006GL028545, 2007

2. New satellite method unclouds water-vapor measurements

A new satellite method overcomes an obstacle to measurements from space of atmospheric water vapor. When viewing the atmosphere above land obscured by clouds, satellites often have trouble measuring how much water vapor is present from the Earth’s surface to the top of the atmosphere--a quantity known as the precipitable water vapor. Merritt Deeter has now used a microwave radiometer aboard NASA's Aqua spacecraft to determine the precipitable water vapor. The new approach has little sensitivity to clouds, and it works during day and night and over ocean and land surfaces, Deeter reports. For the study of climate and weather, water vapor is important because of its role as a greenhouse gas and its relationship to clouds and precipitation. Deeter tested his method against precipitable-water-vapor data collected from a network of Global Positioning System receivers. The comparison showed good agreement, except over regions with dense vegetation.