HR: 1400h
AN: V23A-07    [Abstracts]
TI: Explosive and Phreatomagmatic Activity from San Salvador Volcanic Complex (El Salvador) and Their Effects on El Cambio Archaeological Site: a Review of the Last 3000 yrs. Based on Volcanic Stratigraphy Data
AU: * Ferrés, D
EM: dolosv@yahoo.es
AF: Instituto de Geofísica. Universidad Nacional Autónoma de México, Ciudad Universitaria. Coyoacán, Mexico, DF, 04510, Mexico
AU: Delgado, H
EM: hugo@geofisica.unam.mx
AF: Instituto de Geofísica. Universidad Nacional Autónoma de México, Ciudad Universitaria. Coyoacán, Mexico, DF, 04510, Mexico
AU: Pullinger, C
EM: cpullinger@snet.gob.sv
AF: Servicio Nacional de Estudios Territoriales, Km. 5,5 Carretera Santa Tecla y Avenida Las Mercedes, San Salvador, El Salvador
AU: Castillo, R
EM: rafa_ars2003@yahoo.com
AF: Universidad de San Carlos de Guatemala, Ciudad Universitaria. Edificio S-1. 3r nivel., Ciudad de Guatemala, Guatemala
AU: Chávez, H I
EM: hugo_iki@yahoo.com.mx
AF: Universidad Tecnológica de El Salvador, Escuela de Arte y Cultura. 1a Calle Poniente., San Salvador, El Salvador
AB: El Cambio archeological site (ECAS; Zapotitán Valley), 4 km NW from the San Salvador Volcanic Complex comprises 3000 yrs. of pyroclastic record. Sheets (1983) identified different levels rich in cultural remains intercalated within the volcanic deposits, indicating that different prehistoric settings were affected by San Salvador volcano eruptions, and giving information on the reoccupation frequency in the area. Accordingly, ECAS was occupied since the Late Pre-Classic period until before the last plinian eruption of Ilopango Caldera (425AD) reference, that originated the Tierra Blanca Joven (TBJ), pyroclastic deposits generally used as key-layer in stratigraphic reconstructions. Within the next two centuries, there is no evidence of human occupation at ECAS until the end of Late Classic which was a period of maximum splendor in the valley. During this time the area was affected by at least 3 eruptions from the San Salvador volcanic complex that produced the: Laguna Caldera volcanic fall deposits (which affected Joya de Cerén archeological site in 625AD), "Talpetate" surge deposits or Toba de San Andrés (600-900AD), and fall deposits of El Playón volcano (1658). We report new data on volcanic stratigraphy and archeological history including the following: a) the phreatomagmatic nature of eruptions that affected the area, the new excavations allowed the detailed study of surge deposits indicating magma-water interaction at Laguna Caldera and El Playón, previously considered strombolian eruptions; b)document the occupation of ECAS during Middle Pre-Classic period, new surge deposits below TBJ have been identified (with Middle Pre-Classic artifacts and pottery), that had not been documented before, extending the historic record up to 3000 yrs. BP. and c) detailed study of the "Talpetate" deposits, this sequence consists of fall, pyroclastic flow and surge deposits, present in the rim and slopes of San Salvador Volcano, which can be correlated with surge deposits in a wide area in the northwest and west part of the main volcano. Dating of organic material collected recently will help to better constrain the timing and sequence of the eruptive and human settlement events.
DE: 8428 Explosive volcanism
DE: 8455 Tephrochronology (1145)
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly