Earthquakes in Vanuatu are a common occurance but 7.0’s are always news. Vanuatu has another 7+ earthquake today, the 3rd in less than a month, the fifth in just over a year; no damage expected but wow are they getting hit this year!
Searching the USGS databases I find 23 7 or higher magnitude quakes along this subduction zone since 1973. The Indo Australian Plate is subducting under a portion of the pacific plate causing the islands of Vanuatu to rise out of the sea and the volcanoes in the area. There have been 4 7+ quakes in the zone this year, 2 in August, today’s and one in January. Since 1973 there were 2 in the 1970’s, 2 in 19080 and 2 in 1981, 7 in the 1990’s and 5 in the 20’s and 5 in the last year.
Looking further afield and looking at times and distances there is a recurring pattern of large quakes in the north of the zone, followed by quakes progressing to the south. The current progression started in 2009 October with quakes at 13.01°S, 166.51°E and progressing this one at 20.585°S, 169.696°E. So there you have it another zone that shows a lot of action and will for a long time to come. In the last 30 years the amount of quakes especially at the 7+ range, has been increasing and showing a classic Earthquake storm pattern.
Earthquake storm and more quakes per year!
Does this pattern hold true for thousands of years, we don’t know the data before 1973 is spotty at best but with the available data we can go back to 1878 for significant quakes, 7 or higher. There were few reported before 1910. In 1910 there were 4 but from then to the 70’s there were only a couple per decade so the recent upswing to 5 per decade or so is new and so over the last century and a half or so the progression is to a new active period.
So if you are in the areas of Indonesia to New Zealand I would expect you to get more quakes and they may even get to be even more per year before it drops back to a more normal and less shaky future. Gotta love those earthquakes.
- 7.0 earthquake strikes near Vanuatu in South Pacific (news.blogs.cnn.com)
- South Pacific activity (echlinm.wordpress.com)
- Vanuatu has 2 mag 7 quakes (echlinm.wordpress.com)