Characterizing Deformation Along an Early-Stage Rift: GPS Observations from the Northern Lake Malawi (Nyasa) Rift

The Malawi (Nyasa) Rift is a prominent example of immature rifting located along the southern East African Rift System. The SEGMeNT (Study of Extension and maGmatism in Malawi aNd Tanzania) project installed a new network of 12 continuous GPS sites in Malawi, Tanzania, and Zambia. Using this new data along with data from other existing sites in the region, I examine the present-day deformation along the Malawi Rift and surrounding areas. The GPS data is used to constrain a tectonic block model of the Malawi Rift in order to produce estimates of angular velocities of the blocks, which are then used to derive fault slip rates and linear block velocities. The new data around the Malawi Rift suggests an additional block may be required to explain the observed deformation. My preferred model predicts that extension rates in the area are slower than previous studies suggested (3.8 ± 0.7 mm/yr; Stamps et al., 2008) with a cumulative rate 2.35 ± 0.65 mm/yr in the northern Malawi Rift and 1.26 ± 0.85 mm/yr along the southern Malawi Rift.