2007 Solomon Islands earthquake

2007 Solomon Islands earthquake

UTC time	??
Magnitude	8.1 Mw
Areas affected	Solomon Islands, Papua New Guinea
Casualties	43

The 2007 Solomon Islands earthquake took place on April 1, 2007, near the island of Gizo, in the Solomon Islands. Its magnitude was calculated by the United States Geological Survey (USGS) as being at 8.1 on the moment magnitude scale.

According to the USGS, the earthquake was recorded around 7:39:56 a.m. local time (UTC+11). The focus was Template:Unit km deep and Template:Unit km South South-East of Gizo township on New Georgia Islands in Western Province. Since the first earthquake there have been numerous aftershocks, the worst of which measured 6.2 on the moment magnitude scale.

Effects

At least forty-three people are reported to have been killed and sixty reported missing when a tsunami triggered by the earthquake struck the Solomon Islands, wiping out thirteen or more villages. Thousands were left homeless, and damages are estimated in millions. Rescuers are trying to reach other islands, and the reported death toll is thus expected to rise. In South Choiseul, waves 10 meters high swept away villages, gardens and a hospital. About 900 homes were destroyed and 5000 people left homeless.

The tsunami reached Papua New Guinea, with a family of five reportedly missing from a remote island in Milne Bay Province, which was in the tsunami's path.

Aid workers have reported that an outbreak of diarrhoea has emerged among the survivors. However, the UN reported that the outbreak and other diseases are under control.

The island of Ranongga in the New Georgia Group was lifted three meters by the earthquake, causing its beaches to shift outwards of up to 70 meters. Large coral reefs in the area are now largely above the surface and local fishermen are worried that the fishing grounds have been destroyed. However, Australian scientists said the exposure of the reefs are a normal part of island building and that careful wildlife management can preserve the reefs that remain.

Response

Warnings

Areas affected by the main and aftershock earthquakes

A tsunami warning was issued for the South Pacific Ocean, and advisories issued for Japan and Hawaii. The Australian Bureau of Meteorology issued a warning for Australia's eastern coast, from Queensland's Barrier Reef to Tasmania, and beaches along the coast were closed, while many evacuated to higher ground. However, as the epicenter was close to the Solomon Islands, the tsunami hit before the Hawaiian Pacific Tsunami Warning Center released the warning.

High-magnitude ocean waves propagate at speeds near 25 meters per second, which means that they traverse the 25 kilometer distance from the epicenter to Gavo in 1000 seconds: less than 20 minutes. Fortunately, the S-waves from the earthquake shook the ground and alerted the population, allowing many to flee to high ground before the wave struck.

Aid response

Australia has offered AU$2 million in aid, while New Zealand has offered NZ$500,000 and sent supplies in an air force plane. The United States has so far contributed US$250,000 in aid. Taiwan has contributed US$214,000 and shipment of 1,000 kg of rice. France has also airlifted supplies via New Caledonia. The United Nations has established a field hospital in Gizo, with a total of eight planned for the entire country, and has also established three camps for internally displaced persons. Australian and Canadian medical teams have also been deployed across the islands. Papua New Guinea, itself affected by the tsunami, has contributed US$340,000 and a light plane that can better access smaller, more remote airstrips. UNICEF has issued an appeal for US$500,000 for both the Solomon Islands and Papua New Guinea. Separately, the Red Cross has issued an appeal for US$800,000. The remoteness of some villages meant that aid did not reach them until several days after the tsunami occurred. However, the Associated Press has reported that Gizo's airport has reopened, easing the delivery of supplies. A Taiwanese fishing boat ran aground on coral reefs while delivering supplies, but it was successfully evacuated by a United States Navy helicopter. The boat's crew managed to free the vessel from the rocks a few days later.

Aftermath

Francis Billy Hilly, the MP for Simbo Island where 11 people died, said that those who had previously resisted resettlement away from the island's active volcano are now reconsidering their options. The national government may also relocate islanders away from low-lying areas pending a review of long-term rehabilitation and disaster preparedness plans. Many Solomon Islander Christians celebrated Easter in whichever way they could, and at least seven babies were born since the tsunami hit. The Australian government announced that a network of five tsunami warning buoys will be deployed along its Pacific coast, with two buoys stationed in the Papua New Guinea/Solomon Islands area.

Tectonic summary

The earthquake occurred along the boundary of the Pacific plate with, respectively, the Australia, Woodlark, and Solomon Sea plates. The latter three plates converge to the east-northeast or northeast against the Pacific plate with velocities of 90–105 millimetres/year. Along much of the plate boundary between the Pacific plate and the Australia/Woodlark/Solomon Sea plates, relative plate-motion is accomplished principally by subduction of the Australia/Woodlark/Solomon Sea plates beneath the Pacific plate. The April 2 earthquake's location and focal mechanism are consistent with the earthquake having occurred as underthrusting of the Australia/Woodlark/Solomon Sea plate beneath the Pacific plate, as part of the broader northeast-directed subduction process.

The Solomon Islands arc as a whole experiences a very high level of earthquake activity, and many shocks of magnitude 7 and larger have been recorded since the early decades of the twentieth century. The April 2 earthquake, however, nucleated in a 250 kilometre-long segment of the arc that had produced no shocks of magnitude 7 or larger since the early 20th century.

External links

• Stuff.co.nz:Tsunami fears after massive Solomons quake
• Associated Press: Tsunami hits Solomons
• Australian Bureau of Meteorology Tsunami Warnings summary
• NOAA - Solomon Islands - Historic Quakes
• Reuters - Solom Islands Tsunami Damage
• UNOSAT - Potential Tsunami Affected Areas
• Solomon Islands Government