A large part of central Alaska and the whole of northeast Alaska are dominated by intraplate tectonics. In this tectonic regime, earthquakes are primarily restricted to the crust (≈40 km); their magnitudes and density decrease northward. In terms of principal stresses — σ1 (compressional = P), σ2 (intermediate = B) and σ3 (tension = T), where σ1 > σ2 > σ3, the state of stress in the crust of central and northeast Alaska obtained from focal mechanism solutions (Biswas et al., 1986a) shows nearly horizontal orientations of P and T and nearly vertical orientations of B.

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