Deformation of the seismogenic zone in the northeastern part of the Izu Peninsula, Japan, inferred from GNSS observations

Abstract

AbstractThe Izu collision zone, which is characterized by the collision between the Izu-Bonin arc and the Honshu arc, is located in the northernmost part of the Philippine Sea Plate. Particularly in the northeastern margin of the zone, numerous large earthquakes have occurred throughout history. To clarify the convergent tectonics of this zone related to the occurrence of these large earthquakes, in this study we collected and analysed Global Navigation Satellite System (GNSS) observation data from the Izu collision zone. The result verified that a shear deformation zone exists in the northeastern part of the Izu Peninsula, which agrees with the maximum shear directions in the left-lateral slip of the active Kita-Izu Fault Zone in the study area. In the shear deformation zone, the seismic activities both in the eastern part of the Tanzawa Mountains and the northeastern part of the Izu Peninsula may be related to each other because the temporal patterns of the seismic activity in both areas are correlated. Based on the relative motion between the main part of the Izu Peninsula and the subducting forearc of the Philippine Sea Plate, the shear zone can be regarded as a transition zone affected by both plate collision and subduction.