Glenn Spinelli Effects of fluid circulation in ocean crust on subduction zone temperatures and metamorphism
Subduction zone thermal model applications Seismogenic zone temperatures Sediment alteration and dewatering Slab metamorphism
Hypothesis developed for Cascadia Using temperatures to estimate potential earthquake rupture area in subduction zones
Thermal limits on subduction zone seismicity Hyndman and Wang, 1993 Blanpied et al., 1991;1995 creep quake
“A critical confirmation of the constraints on the seismogenic zone provided by thermal models is comparison with actual thrust earthquake data.” Hyndman and Wang, 1993 Extent of Cascadia seismogenic zone estimated from thermal models
Using temperatures to estimate potential earthquake rupture area in subduction zones Hypothesis tested in Nankai
150 – 350 ˚C limits on seismogenic zone applied to: Cascadia Hyndman et al., 1993Oleskevich et al., 1999Wang et al., 1995Harris & Wang, 2002Currie et al., 2002 Gutscher & Peacock, 2003Hippchen & Hyndman, 2008Marcaillou et al., 2008 Nankai Alaska Chile Costa Rica Mexico Ryuku Ecuador / Columbia Sumatra New Zealand Fagereng & Ellis, 2009
Nankai thermal state revisited Spinelli & Wang, 2008 Baba & Cummins, 2005
Spinelli & Wang, 2008
Conclusions, part 1 When fluid circulation in subducting crust is considered, Nankai seismogenic zone extends from ~ ˚C Including hydrothermal circulation reduces Nankai seismogenic zone temperatures by ˚C
Effects of hydrothermal circulation outside the seismogenic zone Alteration of incoming sediment Slab alteration
Incoming sediment alteration
Slab alteration Spinelli & Wang, 2009
Fluid circulation in subducting crust yields margin temperatures consistent with: 1) surface heat flux 2) sediment alteration 3) slab metamorphism Conclusions, part 2 warmed cooled
Thermally modeled subduction zones
Future work Examine effects of hydrothermal circulation on temperatures in Cascadia and other subduction zones