HR: 0800h
AN: T41A-0354    [Abstracts]
TI: Segment linkage in Afar via magma intrusion: the birth of a transform fault?
AU: * Aronovitz, A C
EM: aaronovi@mail.rochester.edu
AF: EES Department, University of Rochester, Rochester, NY 14627, United States
AU: Ebinger, C J
EM: ebinger@earth.rochester.edu
AF: EES Department, University of Rochester, Rochester, NY 14627, United States
AU: Campbell, E
EM: ecampbell@earth.rochester.edu
AF: EES Department, University of Rochester, Rochester, NY 14627, United States
AU: Keir, D B
EM: d.keir@gl.rhul.ac.uk
AF: Geology Department, Royal Holloway, University of London, Egham, TW20 0EX, United Kingdom
AU: Ayele, A
EM: atalay@geobs.aau.edu.et
AF: Geophysical Observatory, Addis Ababa University, Addis Ababa, Box 2302, Ethiopia
AU: Mitra, G
EM: mitr@troi.cc.rochester.edu
AF: Geophysical Observatory, Addis Ababa University, Addis Ababa, Box 2302, Ethiopia
AB: Both continental and oceanic rifts are segmented along their length, but the relation between transfer faults and transform faults linking segments remains unclear. How and when do transform faults initiate to link rift segments? Does magma intrusion achieve some of the strain transfer between segments? A temporary seismic array in the volcanically and seismically active Afar rift of Ethiopia provides insights into these two fundamental questions. We analyze the spatial and temporal patterns of earthquakes, and compare these to patterns in high-resolution satellite imagery and space geodetic data from the ongoing seismo-volcanic episode that began in 2005. We integrate these results to understand how stresses are transferred between ridge segments and how this possibly relates to the initiation of transform faults. Earthquake swarms from October 2005 to March 2006 form narrow bands coinciding with NW-SE striking fault zones linking the active Erta' Ale and Tat `Ale magmatic rift segments, and the Dabbahu and Alayta magmatic segments. Step over distances are ~15 km and ~20 km respectively. The time and spatial distribution of these seismic events as well as the correlation of events with magmatic centers suggests that earthquakes are triggered by magma intrusion. These patterns offer insight to magma accommodation along faults and between rift segments, suggesting magma intrusion facilitates transform fault initiation. We compare and contrast active structures during the 2005- 2006 episode with segment linkage patterns preserved in the rock record to understand transform evolution.
DE: 3035 Midocean ridge processes
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8178 Tectonics and magmatism
SC: Tectonophysics [T]
MN: 2007 Fall Meeting