A magnitude 8 earthquake has struck off the Solomon Islands and has given rise to a tsunami and destroyed three villages. The United States Geological Survey says the quake was 28.7 kilometres deep and the epicentre was 347km east of Kira Kira. Australia is not considered to be at risk.
Professor James Goff is Director of the Tsunami and Natural Hazards Research Group at the University of New South Wales. He comments:
“The Mag 8.0 Santa Cruz earthquake was originally reported by the United States Geological Survey to be about 5.8 km deep which made me think “oh no, here we go again, this will be a bad one”, but subsequent bulletins from the Pacific Tsunami Warning Center placed it at 33 km deep which at the very least reduces the likelihood of the tsunami being too bad.
“However, close to the source we hear of villages being destroyed, but equally stories are emerging of people evacuating to higher ground after the earthquake and that is indeed wonderfully encouraging, people are taking the initiative to get out of harm’s way.
“It remains to be seen how regionally significant this tsunami has been, and how bad the damage was from the earthquake, but some of the available data can appear a bit misleading. We hear that a tsunami of around 90 cm was recorded at Lata. We need to remember that this is the amplitude of the wave – the height from peak to trough, and also that this would have been recorded at a tide gauge, NOT on the land. Tsunamis on land can run up considerably higher than their offshore height, hence we hear that some coastal communities have sadly been destroyed. It will only be in the ensuing days and weeks that we find out how big the wave really was when it came on land.
“This part of the Solomon Islands is in a particularly active part of the boundary between the Australian and Pacific Plates, and has seen a swarm of earthquakes recently. In geological terms, this is hot on the heels of the 2007 event that occurred in the Western Province and killed 52 people – an area of different plate boundaries and different activity, but in reality we know very little about the long-term earthquake and tsunami activity of the entire Solomon Islands region and so cannot say with any confidence whether this type of event we have seen today is out of the ordinary or how often we might expect it to happen in the future. Much work needs to be done to improve our understanding of such events in the Solomon Islands for the safety of both local and regional communities.”
Professor Richard Arculus, Professor of Geology at the Research School of Earth Sciences at The Australian National University, comments:
“The earthquake epicentre was at the junction of a complex transform fault running north-eastwards from the southern end of the Solomons Trench to the northern end of the New Hebrides Trench, about 70 km west of the island of Ndende. The active subaerial volcano of Tinakula is located about 90 km northeast of the epicentre. A research voyage in 2002 of the Australian Marine National Facility discovered several active submarine volcanoes located north of the transform fault and west of Tinakula, and some others to the east of Nendo. A number of these volcanoes are associated with mineralising hydrothermal systems that have been the target of submarine mineral exploration companies in the past few years. Ndende is located about 125 km northwest of Vanikoro, known to the island where La Perouse, renowned French explorer, ran aground and likely perished in 1788.”
Tom Worthington is Adjunct Senior Lecturer at the Research School of Computer Science at The Australian National University. He comments:
“The international warning system worked well in this case. The Pacific Tsunami Warning Centre issued an ‘Expanding Regional Warning – Initial’ 12:18pm Canberra time. This was then relayed around the Pacific via various electronic means, including the Internet. I received the warning shortly afterwards by SMS to my phone. However, there are limitations to the local warning which can be given, due to a limited number of tsunami sensors in the Pacific and limited communications in some countries.”