******************************************************************************************** Activity report of Poás volcano, Costa Rica From: "Geoffroy Avard" <gavard@xxxxxxxxx> ******************************************************************************************** Dear all, Since mid-July 2011, incandescence is visible during the day on the “Dome” of Poás volcano, Costa Rica, which has not happened since 1981. This observation is the most spectacular illustration of a change of activity that started several months before. Comparing data from seismic, deformation, geochemical and field measurements to the volcanic phase that occurred between 1980 and 1989, we propose two interpretations: 1) the intrusion of a fresh batch of magma although we find no evidence in the data at hand, and 2) a change in the hydrothermal plumbing system that deviated the flux from the lake to the “Dome”. Depending on the precipitation rates in the following months, possible consequences of this change of activity could be the disappearance of the lake and the enhancement of the sub-aerial emission of gases and particles into the atmosphere with a strong impact on the surrounding environment. The complete report is available here: http://www.ovsicori.una.ac.cr/pdf/2011/Poas_activity-report2011-08.pdf A video illustration is available here: http://www.ovsicori.una.ac.cr/videos/Poas-resumen-2011-08.mp4 ¡Pura Vida! Geoffroy Avard, OVSICORI-UNA. ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxx. To contribute to the volcano list, send your message to: volcano@xxxxxxx. Please do not send attachments. ==============================================================
