Site C0002 ultradeep riser top hole

IODP Site C0002 is the centerpiece of the NanTroSEIZE project, intended to access the plate interface fault system at a location where it is believed to be capable of seismogenic locking and slip and to have slipped coseismically in the 1944 Tonankai earthquake. The primary targets include both the basal décollement and the reflector known as the "megasplay fault" (Tobin and Kinoshita, 2006b). The megasplay fault zone and the accretionary prism block are the location of a newly identified class of earthquakes known as very low frequency (VLF) earthquakes (Ito and Obara, 2006) as well as the first observation of shallow tectonic tremor (Obana and Kodaira, 2009). The megasplay fault reflector lies at an estimated depth of 5000~5200 mbsf, and the top of the subducting basement is estimated to lie at 6800~7000 mbsf (Fig. F6).

The top ~800 mbsf will be drilled and cased during Expedition 326, while a real-time vibration monitoring system is tested and fielded. No new scientific data are expected to be collected during this engineering expedition.