Smithsonian Institution Global Volcanism Network Bulletin v. 20, no. 1, January 1995 Popocatepetl (Mexico) Ash plumes observed in mid-February Popocatepetl central Mexico 19.02 N, 98.62 W; summit elev. 5,465 m All times are local (= GMT - 6 hours) Increases in both the frequency and intensity of ash emissions were noticed by Claus Siebe on 12 and 13 February during fieldwork on the slopes of the volcano. Plumes observed were the highest since this eruption began on 21 December (Bulletin v. 19, nos. 11-12), with an estimated height of ~2,500 m reached on 13 February. Large puffs observed at 1525, 1630, and 1730 on 12 February did not rise very high because of a strong wind blowing towards the NE. On 13 February the wind was weaker, and substantial plumes occurred at about 0930, 1100, 1130, 1525, 1625, and 1950. In addition, anomalously acidic pH values were measured at Ojo de Carbon springs located on the volcanoes S slopes near Tlapanala. During the Holocene, Popocatepetl produced both effusive and pyroclastic activity. About 30 eruptions are known since 1345, although early documentation is poor. Most historical eruptions were apparently mild-to-moderate Vulcanian steam and ash emissions, with larger explosive eruptions in 1519 and possibly 1663. Activity in 1920-22 produced intermittent explosive eruptions and a small lava plug in the summit crater. Minor ash clouds were also reported in 1923-24, 1933, 1942-43, and 1947. Information Contacts: Claus Siebe, Instituto de Geofisica, UNAM, Coyoacan, 04510, Mexico DF, Mexico (Email: firstname.lastname@example.org).