Solomon Islands Tsunami (2007)

On April 2, 2007, a tsunami triggered by an 8.1 magnitude submarine earthquake struck the remotely populated Solomon Islands, killing over 50 people, injuring over 5,000, and leaving over 7,000 homeless. Several aftershocks were reported, with the highest reaching 6.4 magnitude.

An archipelago of over 800 islands, the Solomon Islands is home to over 500,000 inhabitants. Approximately 80 percent of the population's livelihood is agriculture-based, in particular fishing and farming. The islands are situated in a seismically active subduction zone known for producing doublet earthquakes (two quakes similar in magnitude occurring close to one another). The islands are no stranger to natural disasters, having experienced floods, cyclones, landslides, droughts, tsunamis, and earthquakes. Analysis of seismological records from the last 80 years reveals that the islands experience one tsunami on average every four to five years.

Occurring at a complex subduction zone (typical of tsunami-generating earthquakes) where the Australian, Woodlark, and Solomon tectonic plates are subducting beneath the Pacific plate, the depth of the earthquake was estimated at 6.2 miles deep with wave heights reaching in excess of 29 feet, 39 feet on Simbo Island, extending inland as far as 650 feet. Recent research by geoscientists in 2009 has highlighted two unusual components of the tsunami-generating earthquake. It has generally been considered that earthquakes should stop at plate boundaries. However, this earthquake crossed from one plate boundary—the Australia-Pacific—into the Solomon/Woodlark-Pacific. Seismic data indicates that the direction of the earthquake changed abruptly; less than 12.5 miles.

The earthquake occurred at 7:39 A.M. local time, accompanied by strong shaking lasting greater than one minute. As well as generating a tsunami, the earthquake triggered landslides; damaged or killed coral reefs; and caused subsidence, solid shaking, and coseismic uplift. Coastal ecosystems such as mangroves, coral reefs, and fisheries were affected due to the intense shaking and uplift generated during the earthquake. Schools and hospitals were damaged, with some villages reported to have been washed away. Buildings constructed by local [Page 648]materials were wholly destroyed, water supplies were contaminated, and coastal access was limited in some places. Economic damage was estimated in excess of $90 million.

The tsunami struck the low-lying, western side of the islands. Over 36,000 people were estimated to have been affected; the United Nations Children's Fund (UNICEF) estimated that half of that number were children. The nearby islands of Simbo, Mono, Kolombangara, Noro, Vella la Vella, and Choiseul were also badly affected. Many of the victims were in the main town of Gizo, 28 miles from the epicenter of the quake. The town took the brunt of the tsunami waves, which destroyed the town's buildings and infrastructure. Here, 33 died and over 4,000 were affected. Residents reported that the first tsunami wave struck Gizo almost instantaneously after the earthquake occurred.

The government declared a state of emergency. Outbreaks of malaria, diarrhea, and measles in refugee camps were reported. Aid was swift with the governments of the Solomon Islands, Australia, Papua New Guinea, the United States, and New Zealand, as well as the United Nations (UN), all immediately mobilizing and pledging emergency aid. Over 130 camps for displaced residents were established in the aftermath. Due to the remoteness of the islands, it was at first difficult to establish the actual extent of the damage and lives lost. Over 40 aftershocks in excess of magnitude 5.0 were recorded in the region in the three days following the tsunami. This somewhat hampered rescue efforts, as residents who were on higher ground were too frightened to come down, fearing another tsunami in the wake of the aftershocks. Rumors of another tsunami further pushed survivors deeper into the hills into makeshifts camps; therefore, assessing the number of victims and distribution of aid were hindered.

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