cient ocean basin of Alpine Corsica. The Piemonte-Ligura basin closed by subduction during the Alpine orogeny, and the earthquakes took place during the subduction. The exhumed earthquake rocks formed at depths of approximately 50 km and are known as intermediate depth earthquakes, common in present-day subduction zones. The shear heating that developed on the faults resulted in melting of several tons of the mantle peridotite per square meter along the fault zone. The quenched melts (pseudotachylyte) show that the faulting was rapid and associated with earthquakes. The discoveries of exhumed subduction earthquakes allow T.B. Anderson of the University of Oslo and colleagues to study phenomena associated with the abrupt energy release associated with the earthquake faulting. These observations enable interpretations based on the direct study from individual mineral grains to the outcrop scale of the mechanism(s) that triggers earthquake faulting at such depths in subduction zones. Based on their observations of the deformation products of the large earthquakes, they suggest that they were triggered by a self-localizing shear heating process rather than by weakening related to the release of free water in the rocks by dehydration of water-bearing minerals.
LiDAR reveals uniform Alpine fault offsets and bimodal plate boundary rupture behavior, New Zealand
Gregory P. De Pascale et al., Department of Geological Sciences, University of Canterbury, Christchurch 8140, New Zealand. Published online 17 Mar. 2014, http://dx.doi.org/10.1130/G35100.1.
Understanding the behavior of plate boundary faults and the recurrence of major earthquakes along these faults is critical for understanding seismic hazards. Using light detection and ranging (LiDAR) data combined with field mapping, the authors from the University of Canterbury, New Zealand, measured tectonic offsets along Page: 1 2 3 4 5 6 Related biology news :1
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