Contemporary stress orientation features in bedrock, Trøndelag, central Norway, and some regional implications.
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Based on in situ rock stress measurements and contemporary stress orientation structures observed at diverse sites in Trøndelag, it can be shown that the Møre-Trøndelag Fault Complex marks an important structural divide separating crustal blocks with disparate, present-day stress fields. This supports earlier poposals reached by both field and numerical modelling studies; and, in one case, our data confirm published predicitions that constrasting contemporary stress fields should, theoretically, characterise the footwall and hangingwall blocks fo this major fault zone. The prevalent NW-SE horizontal compression recorded in coastal areas of central Norway northwest of the Møre-Trøndelag Fault Complex accords with borehole breakout and earthquake focal mechanism solution data acquired offshore, indicating that this patterns is likely to relate to a distributed ridge-push force arising from divergent spreading along the active axial ridge of the North Atlantic Ocean. Taken as a whole, the combination of in situ rock stress measurements and field observations of drillhole reverse-slip offsets and complementary stress patters existing in exposed bedrock.