Smithsonian Institution Global Volcanism Network Bulletin v. 20, no. 3, March 1995 Popocatepetl (Mexico) Ash plumes; two SO2-flux measurements from January (1-4 kilotons/day) Popocatepetl central Mexico 19.02N, 98.62W; summit elev. 5,465 m All times are local (= GMT - 6 hours) Popocatepetl SO2 flux was estimated twice during January using correlation spectrometry (COSPEC). On 15 January scientists made airborne measurements but were unable to establish a GPS navigational fix for 2-3 hours and so made wind speed estimates from map positions and estimates by their pilot, Sergio Zambrano. On 28 January the plume was traversed by a van on a route between the Puebla airport and a junction N of Atlixco; wind speed was from pilot reports to the Puebla airport. Two 15-minute eruptions of dark ash were noted (at 0922 and 1015). Results of these SO2 flux measurements were as follows: 1) 15 January, 3,680 +- 300 tons/day. 2) 28 January, 2,000 +- 1,000 tons/day. At 1000 on 27 January a light beige plume rose no more than 100-200 m above the crater rim and was visible downwind for about 100 km. In addition, sufficient ash fell on the Puebla airport during the night of 27 January to make the tarmac (airport surface) light in color and to visibly cover freshly washed planes. Information Contacts: Stan Williams, Tobias Fisher, and Caitlin Gorman, Arizona State University (see Ulawun); Claus Siebe and Hugo Delgado, Instituto de Geofisica, UNAM, Circuito Exterior, Cd. Universitaria, Coyoacan, 04510, Mexico D.F., Mexico (Email: firstname.lastname@example.org).