WATCH: Hawaii braces itself for Hurricane Lane

Huge waves have been crashing onto the coast of Big Island, as Hurricane Lane threatens a direct hit on Hawaii. It could be the US island chain's worst storm in a quarter of a century, prompting US President Donald Trump to declare a state of emergency as landslides and flash flooding left roads blocked.

The National Weather Service warned Lane could dump as much as 50 centimetres of rain over parts of Hawaii, triggering flash-flooding and landslides.

Lane - located about 200 miles (320km) south of Hawaii - remained a powerful category four hurricane, packing winds in excess of 130 miles per hour.

The eye was expected to sweep very close to or over the islands, 2 000 miles southwest of the mainland US, sometime later on Thursday.

Tens of thousands of people on the islands have been going into disaster-preparation mode: Lining up at hardware centers, gas stations and grocery stores to stock up on essentials.

Three months ago, parts of Hawaii were facing streams of molten lava as Mount Kilauea erupted.