Is A Great Earthquake Imminent Or Not?

For the earthquake prone Indonesia, the question about whether there will be a big earthquake is probably insignificant. Instead, a more pertinent question should be when it will happen. In the aftermath of the 2004 M9 Sumatra-Andaman Sea Earthquake, the M8.4 earthquake that occurred on September 12th, 2007 has certainly brought some panic. Because this earthquake occurred within a so-called gap where some great historical earthquakes occurred several hundreds of years ago, a very natural question is raised: Is a bigger earthquake treading the heel of this event? The author is trying to answer this question using the LURR method. By examining the temporal and spatial pattern of LURR evolution in Sumatra region, significant LURR anomalies appeared not only prior to the 2004 mainshock, but also prior to the 2006 M7.7 South Java earthquake. Moreover, all the earthquakes larger than M7.0 after the 2006 Java earthquake (2006.7.17 M7. 7) occurred in the predicted zone in the PAGEOPH paper which submitted and accepted before the recent earthquakes occurred (also see the follwing web site). Based on the currently availble data, we find that a bigger earthquake is unlikely to occur in the near future. Although the LURR temporal pattern shows high anomaly before the mainshock of the M8.4 earthquake, the LURR value has dropped since the mainshock, indicating the stability in this region is being restored. On the other hand, the spatial pattern shows the area around the 2004 M9 earthquake has higher LURR value than other areas, indicating that the northern part of Sumatra is still the most unstable. Because of insufficient data in this region, the result and the conclusion are preliminary and subject to further revision when more data is available.