Fault growth at a nascent slow-spreading ridge: 2005 Dabbahu rifting episode, Afar

Details Fault growth at a nascent slow-spreading ridge: 2005 Dabbahu rifting episode, Afar Fault growth at a nascent slow-spreading ridge: 2005 Dabbahu rifting episode, Afar

Dec 2007

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007geoji.171.1226r&link_type=abstract

Geophysical Journal International, Volume 171, Issue 10, pp. 1226-1246.

Astronomy and Astrophysics

Astronomy

22

Continental Margins, Extension, Normal Faulting, Rifts

Scientific paper

We present a preliminary account of the near-field surface strain associated with a major magmatic rifting episode at a nascent slow spreading ridge in the Afar depression. Between 2005 September 14 and October 4, a volcanic eruption and 163 earthquakes (mb > 3.9), including seismic tremor, occurred within the ~60-km-long Dabbahu magmatic segment. Results of the early response team demonstrated that ground deformation, derived from satellite radar data (InSAR), together with seismicity, is consistent with dyke-induced deformation along the entire length of the segment. We document the distribution of brittle strain associated with the early part of this rifting cycle to verify the predicted pattern of deformation and constrain a conceptual model for normal fault growth in Afar, with general application to other slow spreading divergent margins. Our field investigations concentrate on the northern half of the segment, which ruptured through to the surface over a length of >30 km and a width of ~5 km, consistent with the pattern of microseismicity recorded using a network deployed ~1 month after the initial onset of the rifting episode on September 14. Severe ground shaking during the event was more widespread; fresh rock fall is common across the entire magmatic segment, particularly at the intersections between faults. Recent ground breaks, in the form of reactivated or newly initiated normal faults and fissures, opened with horizontal displacements up to 3 m and vertical displacements locally up to 5 m, but commonly ~2 m. These structures are generally subvertical and open along pre-existing cooling joints. Fault offset is greater than expected given the magnitude of earthquakes during the episode. The axial relief that developed consequent on fault and fissure initiation and reactivation during the 2005 Dabbahu episode is consistent with that of the entire magmatic segment. We therefore suggest that melt delivery is sufficiently frequent that favourable stress conditions for faulting are primarily achieved during dyke events.

Affiliated with

Also associated with

No associations

Rating

Fault growth at a nascent slow-spreading ridge: 2005 Dabbahu rifting episode, Afar does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Fault growth at a nascent slow-spreading ridge: 2005 Dabbahu rifting episode, Afar, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fault growth at a nascent slow-spreading ridge: 2005 Dabbahu rifting episode, Afar will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1757662