Boso TTT-Type Triple Junction: Formation of Miocene to Quaternary Accretionary Prisms and Present-Day Gravitational Collapse - Accretionary Prisms and Convergent Margin Tectonics in the Northwest Pacific Basin - page 58

142 E

140 E

North America Plate

Boso
Peninsula

35 N

Pacific Plate

Katsuura Basin

Bando Deepsea Basin

Mogi Fan

Rectangular Basin

Philippine Sea Plate

100 km

33 N

Fig. 3 Bathymetric map of the Boso triple junction area ( top ) (Courtesy M. Nakanishi) and a
single-channel seismic profile across the triple junction ( bottom ) (Line 2 of JAMSTEC cruise
KH86-5, location shown above). The vertical scale on the profile is two-way travel time. The nar-
row arrow indicates the dive site of the ROV KAIKO-10K and the broad arrow indicates a subma-
rine landslide (Adapted from Ogawa et al. 1989 ). The dive area is immediately north of the Mogi
Fan near the triple junction. The black dotted line northwest of the Katsuura Basin shows the strike
of normal faults identified by Iwabuchi et al. ( 1990 ). The Katsuura Basin is a ponded basin contain-
ing a thickness of at least 7,000 m of sediments dammed by the present-day accretionary prism