wave on 16 February 1882; earthquakes and volcanic eruptions occurring in the basin of the Pacific Ocean and along the Pacific Ring of Fire are a possible cause of a tsunami. There is earthquake activity in the Solomon Islands, where earthquakes occurred in relation to the New Hebrides Trench, and movement along the boundary of the Pacific Plate with, respectively, the Indo-Australia, Woodlark, and Solomon Sea plates. Tuvalu has the third lowest tsunami risk of Pacific Island countries, with a maximum tsunami amplitude of 1.6m for a 2000-year return period (comparatively, the highest is 5.2m for PNG, and the lowest is 1m for Nauru). The assessment of the tsunami risk of Tuvalu was that major source of risk was activity associated with the New Hebrides trench. The orientation of the trench vis-à-vis the islands of Tuvalu results in the conclusion that most of the energy originating from New Hebrides trench is likely to be directed towards the southern islands of Tuvalu, so that the tsunami risk is lower for the northern islands when compared to the southern islands. Climate data Environment Island, reef and lagoon habitats Tuvalu consists of three reef islands and six true atolls. Its small, scattered group of atolls have poor soil and a total land area of only about 26 square kilometres (less than 10 sq. mi.) making it the fourth smallest country in the world. The islets that form the atolls are very low-lying. Nanumaga, Niutao, Niulakita are reef islands and the six true atolls are Funafuti, Nanumea, Nui, Nukufetau, Nukulaelae and Vaitupu. Funafuti is the largest atoll of the nine low reef islands and atolls that form the Tuvalu volcanic island chain. It comprises numerous islets around a central lagoon that is approximately 25.1 kilometres (15.6 mi) (N–S) by 18.4 kilometres (11.4 mi) (W-E), centred on 179°7’E and 8°30’S. On the atolls an annular reef rim surrounds the lagoon, with several natural reef channels. A standard definition of an atoll is "an annular reef enclosing a lagoon in which there are no promontories other than reefs and islets composed of reef detritus". The northern part of the Funafuti lagoon has a deep basin (maximum depth recorded of 54.7 m) basin, and the southern part of the lagoon has very narrow shallow basin. The eastern shoreline of Fongafale in the Funafuti lagoon (Te Namo) was modified during World War II; several piers were constructed, beach