Dear Colleagues,

This is a report on the activity at Popocatepetl volcano for the volcanological community through the GVN and Volcano Listserv:

A series of SO2 flux measurements have been carried out since January 1994 at Popocatepetl volcano and especially after the event of December, 1994. The measurements of 1995 went up to nearly 8,000 t/d in March but gradually decreased down to 2,000 t/d in June. A persistent decrease of the gas emissions starting from July put the SO2 flux in values of nearly 100 t/d by December 1995. During the March 5, 1996 event, the renewed ash emissions coincided with SO2 fluxes of up to 15,000 t/d and by these days it has been decreasing down but the emission levels are still high (more than 5,000 t/d).

On Friday (March 29), during a COSPEC flight, Lucio Cardenas, Juan Jose Ramirez and Hugo Delgado observed the appearance of a lava dome on the eastern side of the crater floor with an area of 400 sq. m emplaced on the rim of the inner crater (a destroyed lava dome that formed during the 1920-1927 eruption). This lava dome was observed coming out from a source outside that inner crater but flowing into it. Today (April 1st.) the dome was checked again and was observed filling up most of the inner crater (nearly 60 m deep) and increasing its area up to nearly 600 sq. m. Close observation of the phenomena is planned through helicopter flights and COSPEC measurements besides the telemetered seismic and geodetic network.

Currently, the COSPEC measurements are carried out by the Instituto de Geofisica (National University of Mexico), sponsored by the Secretaria de Gobernacion (Ministry of the Interior) through CENAPRED (Disaster Prevention National Center) using an instrument borrowed from the University of Colima and a plane owned by the Mexican Navy.

Dr. Hugo Delgado Granados
Instituto de Geofisica, U.N.A.M.
Circuito Cientifico, C.U.
04510, Mexico D.F.

Phone:  (525) 622-4145; 622-4119; 622-4124
Fax:  (525) 550-2486