A model for the motion of the Philippine Sea Plate consistent with NUVEL‐1 and geological data

Abstract

We investigate angular velocity vectors of the Philippine Sea (PH) plate relative to the adjacent major plates, Eurasia (EU) and Pacific (PA), and the smaller Caroline (CR) plate. Earthquake slip vector data along the Philippine Sea plate boundary are inverted, subject to the constraint that EU‐PA motion equals that predicted by the global relative plate model NUVEL‐1. The resulting solution fails to satisfy geological constraints along the Caroline‐Pacific boundary: convergence along the Mussau Trench and divergence along the Sorol Trough. We then seek solutions satisfying both the CR‐PA boundary conditions and the Philippine Sea slip vector data, by adjusting the PA‐PH and EU‐PH best fitting poles within their error ellipses. We also consider northern Honshu to be part of the North American plate and impose the constraint that the Philippine Sea plate subducts beneath northern Honshu along the Sagami Trough in a NNW‐NW direction. Of the solutions satisfying these conditions, we select the best EU‐PH as 48.2°N, 157.0°E, 1.09°/m.y., corresponding to a pole far from Japan and south of Kamchatka, and PA‐PH, 1.2°N, 134.2°E, 1.00°/m.y. Predicted NA‐PH and EU‐PH convergence rates in central Honshu are consistent with estimated seismic slip rates. Previous estimates of the EU‐PH pole close to central Honshu are inconsistent with extension within the Bonin backarc implied by earthquake slip vectors and NNW‐NW convergence of the Bonin forearc at the Sagami Trough.

Large gas hydrate accumulations on the eastern Nankai Trough inferred from new high‐resolution 2‐D seismic data

“…The Philipine Sea plate is subducting northwestward beneath the Eurasian plate at about 2 -4 cm/yr along the trough [Seno et al, 1993]. In this area, the position of the BGHS could have been influenced by 1/ tectonic uplift and subsidence and 2/ sea level and water temperature changes.…”

Interaction between two subducting plates under Tokyo and its possible effects on seismic hazards

“…[3] In terms of plate tectonics, the setting under Kanto is rather unique: the westward-subducting PAC encounters on its top side the northwestward subducting PHS along the Sagami-Suruga-Nankai trough (Figures 1 and 2) [Seno et al, 1993;Huchon and Labaume, 1989;Mazzotti et al, 2001]. Although globally not common, isolated cases exist where subducting plates come into contact, for example, in Espanola [Dolan et al, 1998] and in Ontong-Java [Mann and Taira, 2004]; but the interaction of PHS and PAC under Kanto is clearly more extensive and better delineated [Noguchi, 1998;Sekiguchi, 2001;Sato et al, 2005].…”

NanTroSEIZE Stage 1 Expeditions 314, 315, and 316: First Drilling Proram of the Nankai Trough Seismogenic Zone Experiment

“…The Nankai Trough in this region is considered a well-coupled megathrust (Wang and Hu, 2006) and exhibits (Fig. 3), yellow arrows = computed far-field convergence vectors between Philippine Sea plate and Japan (Seno et al, 1993;Heki, 2007). Stars = epicentral location of great earthquakes.…”

“…Resistivity imaging suggested widespread fracturing and variable bedding orientation, and how the evolution of the fault zone has affected the characteristic features in this region are two important issues for post-expedition research. Furthermore, taking into account the relative plate motion velocity of ~4 cm yr -1 between the overriding Japanese islands and the Philippine Sea plate (Seno et al, 1993), we determine the relative total slip distance has to be ~40 km, not 6 km. Therefore, the majority of the total shortening must be taken up elsewhere within the accretionary prism.…”