APCEDI ALERT EQ-SSEA #4, 2004: Series of Earthquakes and Tsunamis Devastate Wide Area of South and Southeast Asia

Misinformation about this Disaster

(1) This disaster is being continually being reported as completely unprecedented and not within the realm of being able to have been generally foreseen, but this is not the case.

Tsunamis generated by the eruption of Krakatoa in 1883 killed over 36,000 people on Sumatra and Java, with tsunamis affecting the wider area in the Andaman Sea.

The December 1881 quake registering 7.9 in the Nicobars and subsequent aftershocks in the 1880s produced notable tsunamis throughout the Bay of Bengal. This is well documented in the following paper in the JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. B4, 2215, doi:10.1029/2002JB001941, 2003:

7.9 Car Nicobar earthquake estimated from tsunamis recorded in the Bay of Bengal
Modesto Ortiz, Departamento de Oceanografia, Centro de Investigacion Cientifica y Educacion Superior de Ensenada, Ensenada, Baja California, Mexico
Roger Bilham, Cooperative Institute for Research in Environmental Sciences and Department of Geological Sciences, University of Colorado, Boulder, Colorado, USA

This article carries a very complete bibliography about tsunamis in this region.

From historical evidence throughout the 1800s-1900s, it is like that a major tsunami event in this area will occur once or twice in every century on average. Furthermore, any number of papers and studies have called for an Indian Ocean Tsunami Warning Mechanism, and this has been a topic at a number of seismic hazard conferences, but the donor communities have not regarded it as a priority despite the historic record. While this current incident is particularly large and the damage is more widespread than has been seen in recent times, the probability of this type of event in this region has been known for some time.

2) This current event is not relegated to the Bay of Bengal and as such should not be referred to as a Bay of Bengal disaster as some major relief groups are doing. This event covers the entire Bay of Bengal, Andaman Sea and the Laccadive Sea and the general open Indian Ocean and as such, should be reported as a major South and Southeast Asia regional event. Even the BBC has been referring to this as a Southeast Asia Disaster, but it has clearly affected two major geographic areas: South Asia and Southeast Asia. It is critical to the understanding of the very widespread and destructive nature of tsunami hazards to properly define the greater regional context of this disaster.

3) Various people, even some seismologists, have stated that the 8.1 quake west of the Auckland Islands, New Zealand and north of Macquarie Island on December 23rd either has or has not contributed to this series of quakes in Asia. The answer is that no one can be sure whether or not this former quake contributed and if it did, how this contribution may have been manifest. Seismology, despite ever increasing sophisitication, is still unclear about many facets and variables related to earthquakes. So for any person to provide certainty one way or the other about the relationship between these two seismic events would not be useful. However, it certainly could warrant a thesis or two.

Kevin Vang
APCEDI Coordinator
http://www.afap.org/apcedi/