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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS002 Oral Presentation 1780
The July 17, 2006 Central Java Tsunamis
Mr. Widjo Kongko
coastal dynamic research center agency for the assessment & application of techno.
Gegar Prasetya, Rahman Hidayat, Dinar C. Istiyanto, Sungsang U. Sujoko
The offshore area of the Java fore-arc from historical record had lack of moderate and large earthquake
or low seismic potential, only the area between 109E to 112E is more active in the past, however, its
relatively lack of shallow event. The 17th July 2006 earthquake with magnitude Mw 7.6 happened within
that area and generated tsunamis. The tsunamis hit the south coast along the central Java Island and
neighborhood shoreline and killed 650 people. From the field survey that had been done, the tsunamis
consist of 3- 5 waves with interval from 5 to 10 minutes. The sea receding first, and the second waves
was the highest. It takes 30 50 minutes for tsunamis to reach the coast and the waves run up and flow
depth varies between 1 m to 4. 6 with exceptional wave run up were found at Nusa Kambangan Island
about 10 20 m. This exceptional run up possibly due to second generating mechanism such as
submarine slumping or landslide at the offshore of the Nusa Kambangan Island. The cause of many
death tolls were possible due to the earthquake was not felt by most of the people who lived on the
coast according to the eyewitnesses, however, it could be minimized if the warning system is
operational within this region. Unfortunately, there is no warning had been issued, and the warning
systems still not in place even though the Great Sumatran Earthquake and Tsunamis had already
brought a lot of effort into the warning system in Indian Ocean region since it happened 2 years back.
This event, again, a raise how important the integration of early warning system based on technology
available and people who really had genuine commitments on this matter, and continuous education
and preparedness of the people who lived along the coast that facing to the subduction zone. This
implies the future re-development and hazards management of Indonesian Coast.
Keywords: central java tsunamis, warning system, hazards management