The Kingdom of Tonga is the only constitutional monarchy in the Pacific and is spread over 700,000 square kilometres of the South Pacific Ocean and comprises of 171 islands, of which 40 are inhabited. It has five Administrative Divisions: Tongatapu (the main Island), Vava’u, Ha’apai, Eua and Ongo Niua. Tongatapu has a predominant share of 73% of the total population, followed by Vava’u 15%, Ha’apai 7%, ‘Eua 5%, and Ongo Niua 1%. Tonga is prone to natural disasters and recent ones included a tsunami that hit Niua Islands in September 2009 and the more recent category 5 cyclone Ian that hit the Ha’api Island group in January 2014. The population of Tonga is 103,036 (2011) and there is a high migration rate, with over 150,000 people living in New Zealand, Australia and The United States of America.