The Solomon Islands archipelago consists of over 1,000 islands, ranging from low-lying
coral atolls to mountainous
volcanic islands, including many
volcanoes with varying degrees of activity.
Bougainville Island is the largest in the archipelago, with an area of 9,300 km2 (3591 sq miles).
Mount Balbi on Bougainville is the highest peak in the archipelago at 2,715 metres.
Geology The Solomon Islands archipelago was formed by the convergence of the
Indo-Australian Plate and the
Pacific Plate. The Indo-Australian Plate and the smaller
Solomon Sea Plate are
subducting beneath the Pacific Plate along the New Britain–San Cristobal
oceanic trench, which runs south of and parallel to the archipelago in the
Solomon Sea. The surface geology of the islands is mostly
igneous rocks, outcrops of
metamorphic rocks,
alluvial lowlands, and uplifted coral islands. Areas of ancient coralline limestone are found on Bougainville. Active and dormant volcanoes are found in an arc extending from Bougainville in the north through the
New Georgia Islands and
Savo Island to Gallego volcano on the northwest end of Guadalcanal. Arc volcanism dates the earliest volcanoes on the islands to the Early/Middle Eocene. The archipelago is bounded both to the northeast and southwest by subduction zones, which pull in opposing directions. The rates of subduction on various zones have varied greatly over time due to the subduction of rough seafloor features, such as
seamounts. Several
ridges have been subducted, associated with periods of
tectonic uplift on certain islands, again with highly variable rates. However, it is believed that subduction around the Solomon Islands represents one of the highest rates of convergence found on Earth at 10–12 cm/yr. Subduction zones around the archipelago are tectonically active, though recorded seismicity is higher on the southern side of the island chain. The largest recorded earthquake from the Solomon Islands was a Mw 8.1 that occurred on April 1, 2007.
Climate The climate of the islands is tropical; however, temperatures do not greatly fluctuate due to the
heat sink of the surrounding ocean. Daytime temperatures are normally and at night. From April to October (the dry season), the southeast trade winds blow, gusting at times up to or more. November to March is the wet season, caused by the northwest
monsoon, and is typically warmer and wetter.
Cyclones arise in the Coral Sea and the area of the Solomon Islands, but they usually veer toward
New Caledonia and
Vanuatu or down the coast of
Australia. == Ecology ==