Chen, P., C. R. Bina, and E. A. Okal, Variations in slab dip along the subducting Nazca plate, as related to the stress patterns and moment release of intermediate-depth seismicity and to surface volcanism, Geochemistry, Geophysics, Geosystems, 2, 10.1029/2001GC000153, 2001.
Abstract. The subducting Nazca Plate shows a high degree of along-strike heterogeneity in terms of intermediate-depth seismicity (~70 km to 300 km), orientation of slab stress and volcanism. We compile the intermediate-depth earthquakes of South America from the Harvard CMT catalogue to determine along-strike dip variations, and explore the variable level of correlation between these observations. Primary results are three-fold: (1) Consistency in the orientation of tension axes, highest level seismicity and occurrence of volcanism all are associated with steeply-dipping regions (20-30 degrees); (2) Volcanism and intermediate-depth seismicity exhibit no direct correlation, suggesting that earthquake faulting is not a necessary condition to transport dehydrated fluids out to the mantle wedge for initiation of melting; (3) Comparison of slab thermal structures between those regions with and without volcanism suggests that for certain wedge widths, the maximum temperature in the mantle wedge is hotter for the former than for the latter.
Copyright © 2001 American Geophysical Union