Tonga consists of 171 islands spread over an area of 748 km², of which 36 islands are inhabited. The islands are in four main groups: Tongatapu, Vava’u, Ha’apai, Niuatoputapu and Niuafo’ou. The capital Nuku’alofa is located on the main island of Tongatapu and has a population of approximately 34,000.

Tonga is highly vulnerable to a range of natural disasters and, as its population is predominantly in low-lying coastal areas and spread over small isolated islands, response efforts are often difficult.

Cyclones are the most frequently occurring disaster, with an average of one per year. In February 2012, Cyclone Jasmine brought heavy rains and flooding to Tonga, which had been impacted by Cyclone Cyril a week prior. The worst cyclone in the history of Tonga took place in 1982, killing six people and impacting 146,512.

In addition to cyclones, natural hazards in Tonga include earthquakes and volcanic activity.  Tonga lies very close to the convergence of the Australian and Pacific tectonic plate, one of the most seismically active areas in the Pacific. The most recent major earthquake to impact the population occurred in May 2006, although no deaths or injuries were recorded. There is a volcano on the island of Niuafo’ou and the last major eruption in 1946 caused the island to be completely evacuated.

Due to its seismic activity, Tonga is also vulnerable to tsunamis. The last significant tsunami hit Niuatoputapu in September 2009. Nine people were killed when six to 17 metre-high waves came inland 600 m and destroyed many villages.

WHO and UNDP are the only UN agencies present in Tonga. OCHA carried out a contingency planning exercise in Tonga in 2010.