****************************************************************************************** Follow up on Turrialba´s first Phreatic eruptions during 5-6 of January 2010 From: "Eliecer Duarte Gonzalez" <eduarte@xxxxxxxxx> ****************************************************************************************** After the first round of phreatic eruptions from Turrialba volcano (Costa Rica), there is a field report available (Spanish) at www.ovsicori.una.ac.cr. A visit to the field on jan 6th shed light about what happened between the night of Monday 5th and early hours of Wednesday 6th. At least two vents (between 20 and 30m wide) opened along the inner walls of W crater, to eject an unestimated volume of preexistent fine particles. A narrow plume (8x40 km) of sediments moved SW up to 40 kms reaching a small portion of the populated Central Valley where most Costarricans live. Thickness of deposits vary from few mm (near the summit) to a fine sheet after some 15 km away from the volcano. Granulometry of particles vary from 1mm, in the proximal area to micras, in the distal areas. No juvenile material was found in the described deposits, on the contrary its color, shape and general aspect coincide with the openings in the upper summit. Strong degassing accompanied of fractionated material is intermittently expelled from the new vents as we write this report. Although the tremor signal decreased, compared to two preceding days, energy is enough to produce columns of several hundreds of meters above the summit. Fortunately nobody was hurt during the initial explosions and most of settlers, 3 kms around the volcano, got evacuated. Damage to crops, machinery and infrastructure has not been assessed although it is believed that it may increase if emissions persist. Details and photos may be found at the above mentioned webpage. ============================================================== 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. ==============================================================
