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THE INFLUENCE OF THE RED SEA RIFTS AND THE GULF OF ADEN RIFTS ON THE LATERAL PROPAGATIONS OF FAULTS IN THE DOBI GRABEN AND ITS SURROUNDING AREA IN THE AFAR DEPRESSION
  • Zelalem Demissie
Zelalem Demissie
Wichita State University

Corresponding Author:[email protected]

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Abstract

The Dobi graben is a NW-trending, Quaternary continental rift found within the East-Central Block (ECB) of the Afar Depression (AD) in northeastern Ethiopia. Extension occurs on steeply dipping faults, where the ratio of maximum displacement to traced fault length extends to four orders of magnitude. We conducted fault population analysis in the Dobi graben using a 30 m resolution Shuttle Rader Topography Mission (SRTM) Digital Elevation Model (DEM). We traced a total of 953 faults. We used the fault displacement length profiles’ tapering directions and the different types of fault propagations’ termination styles to characterize the fault kinematics pattern. Our population analysis results show that ~45% of the normal faults in the Dobi graben are tapering towards the southeast in a manner similar to the Red Sea Rift (RSR) regional strain gradient. On the other hand, our analysis showed that ~40% of the faults in the Dobi graben are tapering towards the northwest direction in a manner similar to the Gulf of Aden Rift (GAR) regional strain gradient. We found the statistical regression correlation coefficients (R-square value) for both the southeast and the northwest tapering faults to be ~0.7. Therefore, we suggest that ~85% of the lateral propagation of the 953 faults in the Dobi graben is highly influenced by the regional strain transfer of the RSR and GAR. Additionally, based on the fault propagation termination styles, our faults population analysis shows that faults which exhibit the half-restricted termination style account for 85% of the 953 faults. The maximum displacement over the maximum length (Dmax/Lmax) ratio of these faults is 0.03, which is in accord with the constant displacement length fault growth model.