On 19 and 20 July, quiet emissions and occasional denser puffs of white vapor from the summit crater were observed. A zone of fumaroles on the S flank of the volcano, free of snow and ~400 m below the summit, also released a similar amount of vapor as that from the summit crater.

Guallatiri, one of N Chile's most active volcanoes, is a symmetrical ice-clad volcano at the S end of the Nevados de Quimsachata volcano group.

Geological Summary. One of northern Chile's most active volcanoes, Volcán Guallatiri is a symmetrical ice-clad stratovolcano at the SW end of the Nevados de Quimsachata volcano group. It lies just W of the border with Bolivia and is capped by a central dacitic dome or lava complex, with the active vent situated on its S side. Thick lava flows are prominent on the lower N and W flanks of the andesitic-to-rhyolitic volcano. Minor explosive eruptions have been reported since the beginning of the 19th century. Intense fumarolic activity with "jet-like" noises continues, and numerous solfataras extend more than 300 m down the W flank.

Information Contacts: J. Sesiano, Département de Minéralogie, Université de Genève, 13 rue des Maraîchers, 1121 Genève 4, Switzerland.