Alba Fossae

Scaled Image

Image Credit: NASA/JPL/ASU

About this image

Alba Fossae is a set of long valleys on the western side of Alba Mons. These valleys are referred to as graben and are formed by extension of the crust and faulting. When large amounts of pressure or tension are applied to rocks on timescales that are fast enough that the rock cannot respond by deforming, the rock breaks along faults. In the case of a graben, two parallel faults are formed by extension of the crust and the rock in between the faults drops downward into the space created by the extension. Numerous sets of graben are visible in this THEMIS image, trending from north-northeast to south-southwest. Because the faults defining the graben are formed perpendicular to the direction of the applied stress, we know that extensional forces were pulling the crust apart in the west-northwest/east-southeast direction. The large number of graben around Alba Patera is generally believed to be the result of extensional forces associated with the uplift of Alba Mons. Numerous small channels are visible at the top of this image and are related to lava flows in this region.

Please see the THEMIS Data Citation Note for details on crediting THEMIS images. 


Image ID: 
V94023018 (View data in Mars Image Explorer)
2023-02-24 04:33
Thu, 2023-06-01
256 pixels (19 km)
3792 pixels (285 km)
0.075203 km/pixel
0.0760417 km/pixel


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