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An earthquake swarm of well over 200 events was recently detected along the Gakkel Ridge in the central Arctic Ocean. The swarm occurred between January and August of 1999 and was localized between longitudes 70°E and 90°E (Figure 1a ) . Over the past few decades, only a few randomly clustered earthquakes had been detected along the 1800‐km‐long ridge. Evidence from moment tensor solutions indicates that this swarm originated as a tectonic rifting episode, with double‐couple normal faulting, and transitioned in early March of 1999 to more volcanic origin with strongly non‐double‐couple events. This is the first direct evidence of recent volcanic activity in the high Arctic. Because seismic activity is low at slow and ultra‐slow spreading ridges, the swarm provides an unprecedented opportunity to investigate crustal processes along the ridge.

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SUMMARY Recent investigations on shear wave splitting from recordings of permanent and temporary Antarctic seismological stations have lead to a greater understanding of the upper mantle dynamics of the Scotia Sea region and the continental margin in the eastern Weddell Sea in terms of their tectonic evolution. The analysis of shear wave splitting from teleseismic core (SKS, SKKS, PKS) and direct S waves reveals the seismic anisotropy and the strain field of the upper mantle. Similar to the Caribbean, anisotropy structures in the Antarctic Peninsula and Scotia Sea regions are assumed to be influenced by mantle flows in easterly directions around the subducting Nazca plate. In general, anisotropy polarization directions in the Scotia Sea do not contradict this hypothesis, with polarizations oriented nearly E‐W and therefore aligning with the suggested mantle flow patterns. Anisotropy strengths decrease from delay times of δt=1.8 s (PMSA, Palmer Station) in the west towards the east with delay times of δt=0.3 s beneath HOPE (South Georgia) and CAND (Candlemas, South Sandwich Islands). Nevertheless, a lithospheric and therefore fossil origin cannot be ruled out. Only the exceptionally high delay times at PMSA probably originate in part from recent asthenospheric flow around the subduction slab of the former Phoenix Plate beneath the northwestern margin of the Antarctic Peninsula. The continental margin of western Dronning Maud and Coats Land plays a crucial role in understanding the early processes during the break‐up of Gondwana. Upper mantle seismic anisotropy with delay times well over δt=1 s in this region gives new constraints on ancient deformation processes during break‐up and former episodes. Two‐layer modelling reveals Archaean anisotropy in the upper layer corresponding well to polarization directions of the South African Kaapvaal Craton. Lower layer anisotropy is assumed to have been created during early Gondwana rifting stages.