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Withdrawn: Red Sea Rifting and Cenozoic Volcanism in Saudi Arabia: New Insights from Tomographic Imaging Across the Rift

We present new P-, S-wave and Poisson’s ratio tomographic images of the subsurface structure in the Red Sea rift zone between Saudi Arabia and Egypt using a large number of travel time data from the Saudi and the Egyptian seismological networks. This area comprises the youngest volcanic field (known as the harrat) in Saudi Arabia (Harrat Lunayyir, 1.5Ma), the suspicious seismogenic zone in the Egyptian Red Sea coast (Abu-Dabbab) and the unique shear zone in the Red Sea (Zabargad Shear Zone).

A moderate seismic swarm of ~ 34000 events was recorded in the Lunayyir volcanic field in 2009 with the largest magnitude attaining M5.7. This activity raised the query about the tectonic/volcanic nature of this activity. No such activity is observed in the Egyptian side. However, a large number of micro-earthquakes strikes the area of Abu-Dabbab continuously. In general, our 3-D images show strong heterogeneity in the crust beneath the study area. Lunayyir volcanic field is found to be uniquely related to the adjacent Red Sea shear zone. Preliminary results depict low velocity, high Poisson’s ratio anomaly channels extending between the Red Sea Shear Zone and the Harrat Lunayyir seismic swarm area. These channels may portray a trail of shallow-level magmatic bodies beneath Saudi Arabia’s Red Sea offshore and Harrat Lunayyir areas. In contrast, the seismogenic zones in Abu-Dabbab – Marsa-Alam area are entrapped in a complex V-shaped high velocity anomaly associated with some patches of low velocity anomalies. This V-shaped anomaly, which apparently dips eastward towards the Red Sea, is strongly controlled by the inherited Precambrian structures and could be related as well to the early stages of the Red Sea rift tectonics.

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Presentation Time: Pacific

Presenting Author: Mohamed F. Abdelwahed

Student Presenter: No

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