Introduction

The most complex subduction systems on Earth extend from the Java–Sumatra trench eastward across Indonesia and the Solomon Islands to Vanuatu and the Tonga–Kermadec trench. The northern end of the Sunda Plate is in southwest China at the Red River right-lateral fault zone south of the Xianshuihe and other left-lateral faults. The Sunda Plate includes the Shan Plateau east of the Sagaing fault in Myanmar, and extends across Malaysia into western Indonesia. The Philippines contains trenches on both west and east sides, extending south from Taiwan, covered in Chapter 9. Eastern Indonesia includes the eastern end of the Java–Sumatra subduction zone, which has ridden up over the passive margin of the Australia Plate, as well as the complex, arcuate subduction zones of Sulawesi, Halmahera, the Banda Sea, the island of New Guinea, and islands to the east. The Kermadec trench extends southward into the Hikurangi trench off the east coast of the North Island of New Zealand. These regions have been the object of interest for nearly a century, but except for New Zealand, the Philippines, and Sumatra, the study of crustal faults in most of this region is in an early stage relative to study of the subduction zones.

New Zealand is one of the most advanced nations on Earth in the understanding of its earthquake faults, in part because an active strike-slip fault extends through Wellington, its capital city, and in part because the country has been struck by damaging earthquakes in 1848, 1855, 1888, 1929, 1931, 1968, and most recently in 2011. Like the Philippines, New Zealand contains trenches on both sides with opposite vergence, and, also like the Philippines, these trenches are connected by major plate-boundary strike-slip faults, the Philippine fault of the Philippines and the Alpine fault of New Zealand. Australia, to the west, is a stable continental region, but it has been struck by a special class of SCR earthquakes that in several cases strike the same fault only once, a different problem than SCR earthquakes in New Madrid in the American Midwest or the Kachchh region of India. In this and the previous chapters, I take a more restricted view of SCR earthquakes and continental microplates. For example, the Ordos region of North China is bounded by faults that have generated large earthquakes, but these earthquakes are not included as SCR events, even though the Ordos is not on a plate boundary.