New shear wave splitting measurements using broadband seismic data recorded by the BX seismological network in Botswana.

New measurements shear-wave splitting (SWS) were determined using a teleseismic dataset from 21 broadband seismic stations belonging to the GSN-BX network in Botswana archived at IRIS-DMC. The stations are distributed across major geologic terrains such as the Kaapvaal craton, Limpopo Mobile Belt and Zimbabwe Craton. Earthquakes with magnitude larger than 5.2 mb with epicentral distances in the range of 90° and 180° were analyzed for SKS (S-wave traversing the core as P-wave) and SKKS (S-wave traversing the core as P-wave with one reflection from inner side of the Core Mantle Boundary) phases, while PKS (P-wave bottoming in the core and converting to S-wave at the Core Mantle Boundary) phases were analyzed in the range of 130°-165°. SWS parameters were calculated at each station by minimizing the energy on the transverse component of the PKS, SKKS, and SKS phases (hereafter collectively called XKS). The measurement included the polarization direction ϕ, which gives a reliable indication of the alignment of olivine in the upper mantle, and, the delay time dt between the arrival times of the fast and slow travelling split shear waves. The value of dt is related to the intrinsic anisotropy and thickness of the anisotropic layer. The SWS parameters provide insights into the present and past deformation processes of upper mantle.

Geotechnical investigation of soil properties in Hatsalatladi village, Botswana; Insights from aeromagnetic, laboratory soil tests and Rayleigh wave dispersion datasets.

Soil tests and Multichannel Analysis of Surface Waves (MASW) data were conducted in Hatsalatladi village, Botswana, to investigate the occurrence of ground fissures within the village and to identify the likely causes of the fissures and their depth extent. The MASW data were collected to gain insights into the variation of shear wave velocity with depth. The dataset shows that the shear wave velocity ranged from 150 m/s - 500 m/s, with Poisson's ratios ranging from 0.02 to 0.25. A low-velocity zone (LVZ) was observed in the upper 5 m of the subsurface with velocities ranging from 200 m/s to 350 m/s. The soil plasticity was measured through the plastic and liquid Atterberg tests. Atterberg limits measurements obtained from the three survey sites show that the plastic index of the soil samples collected from depths of 1 m fall within the 10-20% range. Specifically, the Filled Crack survey site had a plastic index of 16%, while the Abandoned House and Bridge sites had 18.7% and 13.5%, respectively. Soil samples from Filled Crack and Abandoned House site revealed a linear shrinkage of 6.4%, while the Bridge site soil sample had a linear shrinkage of 2.9%. The sieve analysis test results are also presented.