************************************* Etna activity update ? December 2005 ************************************* From: Sonia Calvari <calvari@xxxxxxxxxx> The 2004-2005 summit eruption on Mount Etna ended by March 2005 (Burton et al., 2005), leaving only a low and quiet degassing at the summit craters of the volcano until November. Between the end of November and early December 2005 a significant increase in the SO2 output was accompanied by an increase of the volcanic tremor and a minor deformation of the summit part of the volcanic cone. On 16 December 2005 an explosive sequence has been recorded by the INGV-CT seismic network, localized at the summit of the volcano, accompanied by a contemporary increase in the SO2 emission, that reached peaks of 10 times the background level. On 22 December the increase in gas pressure was accompanied by a dilute emission of juvenile ash from the Bocca Nuova crater. This indicated the opening of this vent, blocked since the end of the summit eruption. However, the very fine-grained size of the ash suggest a deep level of the magma column within the conduits. References Burton M., Neri M., Andronico D., Branca S., Caltabiano T., Calvari S., Corsaro R.A., Del Carlo P., Lanzafame G., Lodato L., Miraglia L., Muri F., Salerno G., Spampinato L. (2005) Etna 2004-05: an archetype for geodynamically-controlled effusive eruptions. Geophysical Research Letters, vol. 32, L09303, doi:10.1029/2005GL022527 ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
