HR: 1340h
AN: T33B-1362    [Abstracts]
TI: Onshore observations of land and sea seismic sources in northern Venezuela
AU: Schmitz, M
EM: mschmitz@funvisis.org.ve
AF: Funvisis, Prolongaci¢n Calle Mara, El Llanito, Caracas, 1070 Venezuela
AU: Rocabado, V
EM: vrocabado@funvisis.org.ve
AF: Funvisis, Prolongaci¢n Calle Mara, El Llanito, Caracas, 1070 Venezuela
AU: Sanchez, J
EM: jsanchez@funvisis.org.ve
AF: Funvisis, Prolongaci¢n Calle Mara, El Llanito, Caracas, 1070 Venezuela
AU: Cano, V
EM: vcano@funvisis.org.ve
AF: Funvisis, Prolongaci¢n Calle Mara, El Llanito, Caracas, 1070 Venezuela
AU: Ollarves, R
EM: rollarves@funvisis.org.ve
AF: Funvisis, Prolongaci¢n Calle Mara, El Llanito, Caracas, 1070 Venezuela
AU: Bezada, M
EM: sereno_ccs@hotmail.com
AF: Funvisis, Prolongaci¢n Calle Mara, El Llanito, Caracas, 1070 Venezuela
AU: Avila, J
EM: avigar02@cantv.net
AF: Funvisis, Prolongaci¢n Calle Mara, El Llanito, Caracas, 1070 Venezuela
AU: Vieira, E
EM: ern3stoj2@hotmail.com
AF: Funvisis, Prolongaci¢n Calle Mara, El Llanito, Caracas, 1070 Venezuela
AU: Yanez, M
EM: marianneyanez@cantv.net
AF: Funvisis, Prolongaci¢n Calle Mara, El Llanito, Caracas, 1070 Venezuela
AU: Levander, A
EM: alan@esci.rice.edu
AF: Rice University, 6100 Main Houston, Houston, 77005 United States
AU: * Zelt, C
EM: czelt@rice.edu
AF: Rice University, 6100 Main Houston, Houston, 77005 United States
AB: As part of the BOLIVAR and GEODINOS projects, active seismic measurements were done during the months of April and May 2004 in northern Venezuela between 64 and 70 degree W. Four deep seismic reflection and refraction profiles were acquired perpendicular to the Caribbean-South America plate boundary. To the north, the plate boundary zone with complex plate interactions is marked by the Oca-Ancon, San Sebastian and El Pilar fault zones, a 1000 km long dextral strike-slip fault system, which accommodates a relative movement of 2 cm/year between both plates. From the Caribbean Mountain System in the north, the seismic profiles run into the Falcon Basin in the west and the Guarico and Oriental Basins in central and eastern Venezuela, divided by Frontal Thrust Systems from the Caribbean Mountain System. Further south, the Guayana Craton corresponds to the stable South American plate. Up to now, little is known about the crystalline crustal structure. In western Venezuela, the overall crustal thickness decreases from 45 km in the craton area to around 35 km along the coastline. Air gun shots from the marine refraction lines, recorded by the broadband stations of the Venezuelan national seismic network as well as the BOLIVAR project temporal seismological network, were used to build seismic sections in which first arrivals can be observed at offsets larger than 200 km. This data will be modeled and interpreted using two different approaches: 2D traveltime inversion using a layered model, and 3D tomography using seeking a smoth velocity model. Along the four main profiles, 2 land shots with chemical explosions were fired on each profile in order to provide information on the crustal and upper mantle structures. Data quality is good for the land shots to at least 200 km distance from the shotpoints. We will provide information on the crustal structure and thickness on the northern edge of the South American continent. The use of seismic recorders from IRIS-PASSCAL Instrument Centre and technical support is acknowledged. Contribution to project G-2002000478.
DE: 8100 TECTONOPHYSICS
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting