*************************************************** Poás volcano, Costa Rica resumed phreatic activity *************************************************** From: Eliecer Duarte G. <eduarte@xxxxxxxxx> After 1994 Poas volcano resumed activity with a series of phreatic eruptions. Harmonic tremor was detected in the seismic station 3 days prior to the events. On Friday noon, (march 24, 2006) a strong eruption was emitted from the hot crater lake. At least one of the subsequent eruptions was documented early Saturday. Staff from OVSICORI-UNA visited the east side of the volcano to confirm material charged with water, blocks and sediments from the bottom of the lake. Impact craters were documented in one area ranging from 300 to 700m beyond the source point. Crater size range from some cm to 70cm while, blocks associated ranged from few cm to 50cms and they were scattered randomly in the visited area. Although they did not reached the extracrater area. Fine and superfine sediments were also documented and collected for later analysis. The area visited showed a gray appeareance although the rainy conditions accumulated small ponds of such sediments in crevices and lower drainages. Material collected is composed of preexistent solid material from the bottom of the lake heavily altered by the action of acid and hot conditions during the last 12 years. Some of the more friable samples consist of compacted sediments that have aggregated miscellaneous granulometries. Up to Monday 27 the tremor disappeared to resume normal seismic activity. No impact on surrounding vegetation, visitors or infrastructure has been confirmed. Since this tropical area is in the middle of the dry season there is expectation to what point a vigorous degassing may impact the surrounding, up to small communities, as it did in past similar events (89/90 and 94). ***************************************** M.Sc. Eliecer Duarte G. Observatorio Vulcanologico y Sismologico de Costa Rica. OVSICORI-UNA. fax (506) 2610303 tel (506) 2610781 email:eduarte@xxxxxxxxx or eliduarte@xxxxxxxxxxxxxxxx http://www.ovsicori.una.ac.cr ============================================================== 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. ==============================================================
