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.These faults are described as right lateral or left lateral, depending on which way the movement goes. Strike-slip Faults: Sometimes referred to as a lateral fault, this type forms when the blocks of rock on either side of a vertical (or nearly vertical) fracture move past each other.Reverse faults often form along convergent plate boundaries. Reverse or Thrust Faults: The opposite of a normal fault, a reverse fault forms when the rocks on the “uphill” side of an inclined fault plane rise above the rocks on the other side.Long, deep valleys can also be the result of normal faulting. Normal faults are often found along divergent plate boundaries, such as under the ocean where new crust is forming. It forms when rock above an inclined fracture plane moves downward, sliding along the rock on the other side of the fracture. Normal Faults: This is the most common type of fault. ![]() They’re based on the type of movement they exhibit. Just as there are various types of plate movements, there are also different types of faults. Some faults are visible at the surface, but others lie deep within the crust. More recently, the Sichuan region in China suffered a devastating intraplate earthquake in 2008. ![]() During the winter of 1811–1812, a series of earthquakes struck New Madrid, Missouri. Most earthquakes occur along plate boundaries, but they can also happen in the middle of plates along intraplate fault zones. Sometimes faults move when energy is released from a sudden slip of the rocks on either side. Faults are fractures in Earth’s crust where movement has occurred.
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