A gravimetric method to determine horizontal stress field due to flow in the mantle in East Africa Great Rift Valley
No Thumbnail Available
Date
2023-07
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
The gravimetric approach has been widely used to determine the stress field of subsurface geology
of the earth crust. Mainly this study aimed to determine lithospheric shear stress in the Earth’s
mantle and its temporal changes caused by geodynamical movements. The gravimetric approach
is applied, to evaluate the stress at the base of lithosphere and to detect changes in stress using
static gravity field model EGM08 and GRACE monthly solutions respectively. In addition to the
static gravity field data some physical information about topographic height, crustal thickness, and
lithospheric thickness are incorporated in this method. As a result, more geophysical information
and data are applied for computation of horizontal lithospheric stress in this approach. To do so,
depth of the base of lithosphere determined by subtracting topographic height from lithospheric
thickness is needed, thus the lithospheric shear stress component computed at the base of
lithosphere. Moreover, the comparison of lithospheric shear stress using different static gravity
field models are performed. The estimated horizontal shear stress at the base of the lithosphere
throughout the study area revealed 55.68% of the stress is oriented in a northward direction and
the remaining 44.32% is oriented in the southward direction; 44.41% of the stress is oriented in an
eastward direction and the remaining 55.59% is oriented in the westward direction: and the result
of the estimated horizontal shear stress magnitude ranges from ≈ 0.04 MPa to ≈ 15.32 MPa.
Furthermore, the estimated horizontal shear stress components show good agreement with the
tectonic boundaries and the location of stress regimes in the WSM2016 database, as well as the
seismic events in the study area.