Viti Levu (pronounced ; ) is the largest island in the Republic of Fiji. It is the site of the nation's capital, Suva, and home to a large majority of Fiji's population. Geology Fiji lies in a tectonically complex area between the Australian Plate and the Pacific Plate. The Fiji Platform lies in a zone bordered by active extension fault lines, around which most of the shallow earthquakes in the area have been centred. These fault lines are: the Fiji Fracture Zone (FFZ) to the north; the 176° Extension Zone (176°E EZ) to the west; and the Hunter Fracture Zone (HFZ) and Lau Ridge to the east. The oldest rocks on the island are those formed during the Eocene and Lower Miocene epochs that belong to the Wainimala group. The lower portion of the group is made up of volcanic flows and volcanoclastics, which grade from basalt to trachyte and rhyolite. Geographically, this group is found south of Nadi, including on the peaks of Koromba (at 3528 feet high) and Natambumgguto (at 1242 feet high), and down to Sigatoka. From Sigatoka, the group extends almost all the way to Lodoni, and includes the peaks of Tuvutau (at 3060 feet) and Tikituru (at 3071 feet). Along the southern coast it extends almost to Nausori. The group is intruded by the Tholo Plutonics, which consist of similar-age stocks of tonalite, granodiorite, gabbro and diorite. Mio-Pliocene sandstones, and marl, grading into epiclastics and andesitic Volcanic rocks of the Suva group are found mainly in the river valleys, such as those formed by the Nadi River and Navua River. The Plio-Pleistocene Mba group is found in the northern portion of the island. It consists of porphyritic basalt flows and volcanoclastics, grading into greywacke. Geographically, it includes the peaks of Koroyanitu (at 3921 feet), Malua (at 3294 feet), Monavatu (at 3708 feet), Mount Tomanivi (at 4341 feet), and Ndelamendamu (at 2540 feet). It extends along the eastern coast, almost to Nausori, and includes the Emperor Mine near Vatukoula. Geography, economy and ecology Viti Levu is the largest island in the Republic of Fiji — home to 70% of the population (about 600,000 people) - and is the hub of the entire Fijian archipelago. It measures long and wide, and has an area of . Earthquakes and volcanic eruptions account for the somewhat rugged terrain of the island, which is divided into roughly equal halves by