HR: 12:05h
AN: V22A-08    [Abstracts]
TI: Seismic Pattern Recognition Techniques to Predict Eruptions at the Popocatepetl, Mexico, Volcano
AU: * Novelo-Casanova, D A
EM: dnovelo@geofisica.unam.mx
AF: Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria Delegacion Coyoacan, Mexico, DF 04510, Mexico
AU: Valdes-Gonzalez, C M
EM: carlosv@ollin.igeofcu.unam.mx
AF: Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria Delegacion Coyoacan, Mexico, DF 04510, Mexico
AB: Using pattern recognition techniques, we formulate a simple prediction rule for a retrospective prediction of the two last largest eruptions of the Popocatépetl (Popo), Mexico, volcano that occurred on 23 April-30 June 1997 (Eruption 1; VEI~2-3) and 11 December 2000-23 January 2001 (Eruption 2; VEI~3-4). Times of Increased Probability (TIP) were estimated from the seismicity recorded by the local seismic network from 1 January 1995 to 31 December 2005. We consider a TIP as a cluster of seismic events which occurs in the Popo region in a temporal window several days (or weeks) prior to large volcanic activity providing sufficient time to organize an effective alert strategy. The best predictions are obtained when averaging seismicity rate over a 5-day window with a threshold value of 11 events and declaring an alarm for 45 days. A TIP was issued about one a half months before Eruption 1. Another TIP was detected about five days before Eruption 2. According to our objectives, in both cases, the observed TIPs would have allowed the development of an effective civil protection strategy. Thus, under our model considerations, the two eruptive events were successfully predicted. However, two "false alarm cases" were also issued by our algorithm. An analysis of the epicentral and depth distribution of the local seismicity used by our prediction rule reveals that successful TIPs were issued from microearthquakes that took place below and towards SE of the crater. On the contrary, the seismicity that issued the two observed "false alarms" occurred only below the summit of the volcano. We conclude that recording of precursory seismicity below and SE of the crater together with detection of TIPs as described here, are an important tool to predict future large eruptions at Popo.
DE: 8419 Volcano monitoring (7280)
DE: 8488 Volcanic hazards and risks
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly