The Ontong Java Plateau is a huge oceanic plateau located in the Pacific Ocean, lying north of the Solomon Islands. The plateau covers an area of approximately 2,000,000 km2 (770,000 sq mi), or roughly the size of Alaska, and reaches a thickness of up to 30 km (19 mi). The plateau is of volcanic origin, composed mostly of flood basalts. Although they are now separated by thousands of kilometres, Manihiki Plateau and Hikurangi Plateau were at the time of their origin part of the same large igneous province, forming the world's largest oceanic plateau. It extruded some 100 million km3 of magma, covering approximately 1% of the Earth's surface, in one of the largest volcanic events on Earth in the last 300 million years.