![]() The Woodlark region is formed by orthogonal oceanic spreading at rates of 19–35 mm/yr at the Woodlark Rift in the south and subduction beneath the Bismarck Plates at rates of 67–157 mm/yr at the New Britain and San Cristobal trenches in the north and east ( Wallace et al., 2014). The eastern margin of the Papuan Peninsula and the Solomon Sea has been identified using GPS-based geodesy as the landward extent of the 135,000 km 2 Trobriand microplate – one of the three microplates in the Woodlark region between the much larger Pacific and Australian Plates ( Baldwin et al., 2012 Ott and Mann, 2015). Within this overall pattern of structural variation, abrupt changes in the azimuth of the OSFZ create more localized anomalies in the geomorphological indices. These geomorphological indices indicate that most of the plate boundary uplift occurs along the transpressional and transtensional segments that are connected by the central strike-slip zone. Normalized steepness indices (k sn) and knickpoint clusters are the highest and most concentrated, respectively, for the northwestern transpressional segment of the OSR, moderately high and concentrated along the southeastern segment of the OSR, and the lowest and least concentrated along the central strike-slip segment. In order to illustrate the along-strike variations in neotectonic uplift resulting from the changing structure of the OSFZ, we delineated 3903 river segments in the northeastern side of the OSR drainage divide and derived river longitudinal profiles along each river segment. GPS geodesy reveals that the Trobriand microplate has undergone rapid counter-clockwise rotation since the Late Miocene (8.4 Ma) and that this rotation about a nearby pole of rotation predicts transpressional deformation along the 250 km-long northwestern segment of the OSFZ, strike-slip motion along a 100 km-long central segment, and transtension along the 270 km-long ESE-trending southeastern segment of OSFZ. ![]() The landward extent of the plate boundary between the Trobriand and Australian Plates corresponds to the Owen-Stanley Fault Zone (OSFZ), an onland and continuous 510 km-long left-lateral strike-slip fault that forms a linear, intermontane valley within the elongate Owen-Stanley Range (OSR) and continues as a 250 km-long low-angle normal fault along the margins of Goodenough and Woodlark basins. The area of southeastern Papua New Guinea includes three active microplates – the Trobriand, Woodlark, and Solomon Sea plates – that are being deformed by regional convergence between the much larger Pacific and Australian Plates. Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX, United States.Stratigraphic correlation methods have a potential to address source zone spatial extent and segmentation, and because of the longer time intervals available, it can be used to examine recurrence models, fault interactions, clustering, and other phenomena commonly limited by short temporal records. Marine deposits offer significant opportunities for stratigraphic correlation along the source zone. ![]() Offshore and lacustrine records offer the potential of good preservation, good spatial coverage, and long temporal span. If the seafloor is shaken or displaced, another suite of events may result in further geologic and geodetic evidence of the event, including turbidity currents, submarine landslides, tsunami, and soft-sediment deformation. Onshore, land levels change with elastic unflexing of the formerly coupled plates, thereby resulting in coastal subsidence, uplift, or lateral shift, and the generation of familiar onshore paleoseismic evidence, such as fault scarps, colluvial wedges, damaged trees, landslides, and offset features. During and shortly after large earthquakes, in the coastal and marine environment, a spectrum of evidence is left behind. A large proportion of the world's population lives near coastlines thus, a high proportion of hazard from active tectonics comes from submarine fault systems and volcanic and landslide generators of tsunamis. ![]() Many of the largest earthquakes are fundamentally marine events generated by submarine subduction zones or other plate boundary earthquakes and volcano-tectonic explosions.
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