January 11, 2013 – Earthquakes are like Snowflakes; no two are the same: The graphs above reflect a large database of earthquakes, greater than or equal to 6.0 magnitude, for Indonesia and Japan. There are more quakes in the Indonesia chart (707) than the Japanese exhibit (576) because, on average, there are more quakes in the former country. This was illustrated in a graph I posted on April 17, 2012; in a post title, “A Powerful 6.7 Magnitude Earthquake Struck Valaparaiso, Chile.” That chart reflected 354 earthquakes, greater than or equal to 7.0 magnitude, over the last 39 years by country. Indonesia was number one with 47, followed by Japan with 27.
Both countries have experienced iconic mega-quakes and subsequent tsunamis in the 21st century: (1) Sumatra, Indonesia on December 26, 2004 – 9.1 Magnitude and (2) Japan on March 11, 2011 – 9.0 magnitude. Both mega-quakes involved a subduction zone release event, where the sea floor suddenly rose; producing the quakes and tsunamis.
The differences between such similar quakes are quit striking. The Sumatra event was sudden and unexpected because there were practically no foreshocks signaling the main event. Using a variance of two degrees from the latitude and longitude, the Sumatra quake only had two foreshocks, both on November 2, 2002; a 7.4M and 6.3M. The Japanese quake had three sets of foreshocks: (1) March 14, 2010 – 6.5M, (2) July 4, 2010 – 6.3M and (3) March 9, 2011 – 7.3M, 6.3M and 6.4M.
The Japanese quake had three powerful precursors two days prior to the main event. The Sumatra quake had no warning whatsoever. One minute you’re sunning yourself on a quite beach in Thailand and the next you’re washed away, never to be seen again.
The other major difference is in deaths versus money damages. The Sumatra quake killed over 220,000 people, around the rim of the Indian Ocean. The total money damages are difficult to estimate but are small in comparison to the Japanese event.
The World Bank estimates that the Japanese quake and tsunami cost $235 billion, with 8,650 confirmed dead and 13,150 missing. Damages could rise even higher as Japan struggles to repair nuclear plants effect by the quake.
With two mega-quakes in the first 11 years of the 21st century, I wonder what the next 11 years will bring. Originally published April 21, 2012.
The Master of Disaster