Figure 3: Orientation and magnitude of crustal shear-wave splitting measurements in the Ethiopian and Afar rifts. | Nature Communications

Figure 3: Orientation and magnitude of crustal shear-wave splitting measurements in the Ethiopian and Afar rifts.

From: Mapping the evolving strain field during continental breakup from crustal anisotropy in the Afar Depression

Figure 3

(a) Local earthquake shear-wave splitting measurements in Ethiopia. The arrows are oriented parallel to the fast-polarization direction (φ) and the arrow length is scaled by delay time (δt). Measurements from Keir et al.25 from the MER are in blue, and an average of measurements from the Asal rift in Djibouti are black. New splitting measurements from our study are green. (b) Estimate of magnitude and direction of anisotropy derived from the raw S-wave splitting measurements displayed in a. The arrows are oriented parallel to the fast anisotropic direction and the arrow lengths are scaled to % anisotropy, assuming that S-wave splitting is accrued along the full ray-path length. In the MER, crustal anisotropy is particularly high and in the Boset-Kone (BK) magmatic segment where Quaternary-Recent volcanism is particularly voluminous. The profiles displayed in Figure 4 are x–x′ and z–z′.

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