Although Alba Patera is the largest volcano in aerial extent in the solar system (~6.8 km high and >1000 km in radius), the geologic processes responsible for shaping its exceedingly low-angle flanks remain poorly constrained. These flanks are covered in lava flows, valleys and both radial and annular grabens. Previous attempts, limited by the resolution of the satellite images, assume that the annular grabens formed during the terminal stage of volcanic development whereas surface water flow occurred in the early stage of volcanic construction. In this study, we analyze high-resolution CTX satellite images in conjunction with digital topographic data from MOLA. Our work reveals complex cross cutting relationships between faults, drainage network development and lava flows on the northwestern flank of Alba Patera. We observe a minimum of three generations of lava flows, three generations of drainage channels and three generations of faults. Mutual and successive cross-cutting relationships between drainage channels and faults indicate that the tectonic processes responsible for creating grabens on the volcano flank operated continuously and were coeval with drainage formation. The lava flows are observed to be the oldest geomorphic features and the third generation of faults as the youngest geomorphic features in our mapped region. Crater counting indicates that the surface within the mapped region is Amazonian in age. An analysis of the crater densities reveals a decline in crater densities from the south to the north section of the mapped region. This could be attributed to resurfacing in the north due to sediments deposited by northward flowing drainage channels. Crater counting age estimates for the south section yield a result of ~ 1.74 Ga, +/- 0.12 Ga and ~ 1.35 Ga, +/- 0.26 Ga for the north section. Hence, the younger age estimates of the northern surface could help further constrain the age of the drainage channels and faults on the northwest flank of Alba Patera.

We present new measurements of the surface deformation associated with the rifting

event of 1978 in the Asal-Ghoubbet Rift, Republic of Djibouti using an optical image

correlation technique. Deformation in the rift associated with the event included the

reactivation of the main bordering faults and the development of numerous open fissures

on the rift floor. We combine these new measurements with ground-based observations

from previous work to constrain a kinematic model of the rift consisting of two bordering

faults reaching a depth of 3 km and a vertical dike below this depth. Our modeling

indicates that the horizontal extension collectively accommodated by the faults and

fissures amounts to 2.4-2.8 m, significantly higher than the amount of ~1.2 m estimated

by trilateration alone over a ~10 km baseline. The model suggests that during the 1978

event, magmatic fluids were transferred from a mid-crustal reservoir to the shallow

structures, injecting dykes and filling faults and fissures, reaching the surface in the

Ardokoba fissural eruption.

This project’s objective is to map surface deformation over the Afar Depression since 1997 in real time to characterize fault behavior and contribute to the current repertoire of knowledge surrounding rifting processes. The Afar Depression is a broad extensional region in Eastern Africa, where the diverging boundaries have not yet achieved connection, so extension is distributed across developing arrays of faults and fractures. There has been generally limited attention from previous studies on the amount of divergence accommodated by distributed extension resulting from the transmission of tectonic forces applied to boundaries, in tangent with limited geodetic coverage and observations. To understand the mechanical processes underlying rift evolution, the current strain rate of the crust and its character over time throughout the Afar Depression must be understood in relation with the distribution of Quaternary faulting and rifting. To study the present-day deformation field, we use the technique of Synthetic Aperture Radar Interferometry (InSAR) — a method to measure ground deformation in map — with a dense archive of SAR data from two satellite missions: the Canadian Space Agency's (CSA) C-band RADARSAT-1 and the European Space Agency's (ESA) C-band Sentinel-1 missions. The mm/year resolution of InSAR time series measurements allows us to detect and monitor deformation throughout the Afar Depression in between events as large and fast as significant earthquakes and volcanic eruptions and also as small and slow as small dike intrusions over multiple decades. Using this data, we have modelled multiple discrete faulting events which were not captured before in the geodetic nor seismological record. Finally, to constrain the long-term extension rate and the distribution of extension across the Arabia-Somalian plate boundary, we compiled a detailed estimate of cumulative extension and vertical throw by measuring faults across the plate boundary using a high-resolution German Aerospace Center (DLR) TanDEM-X Digital Elevation Model (DEM).