Java Tsunami (2006)

On July 17, 2006, a tsunami struck Java, killing over 500 people and displacing 50,000. The tsunami was caused by a submarine 7.7-magnitude earthquake, 152 miles south of the Java coast. The depth of the earthquake was just six miles, and the resulting tsunami affected over 186 miles of coastline. The popular beach resort of Pangandaran was badly hit, with reported deaths totalling in excess of 200.

Indonesia is located in an active seismic zone, sitting at the point where three tectonic plates meet. As a result, 60 percent of the Indonesian coastline is identified as at risk from tsunamis. Java, in particular, is tectonically unstable, and although this coastline of Java was unaffected by the devastating 2004 Indian Ocean tsunami, the area is considered active. In 1977, a magnitude 8.3 earthquake resulted in a tsunami with a maximum runup height of 50 feet, killing close to 200 people. In 1994, a tsunami generated by a 7.8-magnitude earthquake killed over 200 people. In May 2006, just two months prior to the Java tsunami, a shallow-depth, 6.3-magnitude earthquake struck, killing over 5,000 people.

The cause of the earthquake was attributed to the thrust faulting of the Australian plate under the Sundra plate at the Java trench. As the rupture occurred slowly, the quake did not generate strong ground shaking. This was corroborated by local residents, who reported that they barely felt the earthquake. However, the earthquake did cause buildings in the capital city of Jakarta to sway.

The tsunami struck a moderately narrow 186-mile area of coastline. The hardest-hit areas were the west and south region of Java; in particular, Pangandaran, Garut, and Yogyakarta reported a significant number of deaths. Many deaths occurred in coastal fishing villages with the economic damage to West Java fisheries estimated to be in excess of $6 million. Damage extended nearly 1,000 feet inland, and houses, schools, hotels, and rice fields were either partially or wholly destroyed. Economic damage was in excess of $30 million. Several powerful aftershocks followed the earthquake, causing many residents to flee to higher ground in fear of another tsunami. However, no further tsunami waves were reported.

The Indonesian authorities were given an advance warning varying between 24 and 45 minutes; however, there was no method in place to alert local authorities on the ground, as Java's warning system was not due to be operational until 2007. The Pacific Tsunami Warning Centre in Hawaii and the Japan Meteorological Agency issued a tsunami warning 12 minutes after the earthquake occurred. India, in turn, issued a tsunami warning for its Andaman and Nicobar Islands, and Australia issued a warning for its Christmas Islands, the nearest land mass to the quake's epicenter. These actions resulted in residents in these areas moving to higher ground, but no damage was reported, and the wave height was reported to be no more than three feet higher than usual.

The high death toll can be attributed to many factors. Inhabitants did not recognize the precursors to an impending tsunami because many did not feel the earthquake, and so were not expecting a tsunami. No warning system was established, leaving inhabitants on the coast unprepared during a low tide, which disguised signs of receding waters. Second, the wave runup height ranged from 16 to 23 feet, although scientists uncovered evidence of a 68-foot wave striking the coastline near Nusa [Page 370]Kambangan Island. Many buildings and houses, especially on the coast, were not built to withstand the tsunami waves. Third, the tsunami struck the coast at 15:19 P.M. local time, when many people, including tourists, were on the beach. Indonesia's tsunami early warning system was launched in November 2008. The network is due to be fully completed in 2010, and will comprise of 160 seismological stations, deep-sea pressure sensor buoys, land-based tidal gauges, and computer modeling. However, some experts have cited that some areas of Indonesia will not be fully covered.

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