Kaohsiung County. Another major earthquake occurred on 6 February 2016, with a magnitude of 6.4. Tainan was damaged the most, with 117 deaths, most of them caused by the collapse of a 17-story apartment building. Terrain The terrain in Taiwan is divided into two parts: the flat to gently rolling plains in the west, where 90% of the population lives, and the mostly rugged forest-covered mountains in the eastern two-thirds. The eastern part of the island is dominated by five mountain ranges, each running from north-northeast to south-southwest, roughly parallel to the east coast of the island. As a group, they extend from north to south and average about from east to west. They include more than two hundred peaks with elevations of over . The Central Mountain Range extends from Su'ao in the northeast to Eluanbi at the southern tip of the island, forming a ridge of high mountains and serving as the island's principal watershed. The mountains are predominantly composed of hard rock formations resistant to weathering and erosion, although heavy rainfall has deeply scarred the sides with gorges and sharp valleys. The relative relief of the terrain is usually extensive, and the forest-clad mountains with their extreme ruggedness are almost impenetrable. The east side of the Central Mountain Range is the steepest mountain slope in Taiwan, with fault scarps ranging in height from . Taroko National Park, on the steep eastern side of the range, has good examples of mountainous terrain, gorges and erosion caused by a swiftly flowing river. The East Coast Mountain Range extends down the east coast of the island from the mouth of the Hualien River in the north to Taitung County in the south, and chiefly consist of sandstone and shale. It is separated from the Central Range by the narrow Huatung Valley, at an altitude of . Although Hsinkangshan (新港山), the highest peak, reaches an elevation of , most of the range is composed of large hills. Small streams have developed on the flanks, but only one large river cuts across the range. Badlands are located at the western foot of the range, where the ground water level is the lowest and rock formations are the least resistant to weathering. Raised coral reefs along the east coast and the frequent occurrences of earthquakes in the rift valley indicate that the fault block is still rising. The ranges to the west of