2006 Pangandaran earthquake and tsunami

An earthquake occurred on July 17, 2006, at 15:19:27 local time along a subduction zone off the coast of west and central Java, a large and densely populated island in the Indonesian archipelago. The shock had a moment magnitude of 7.7 and a maximum perceived intensity of IV (Light) in Jakarta, the capital and largest city of Indonesia. There were no direct effects of the earthquake's shaking due to its low intensity, and the large loss of life from the event was due to the resulting tsunami, which inundated a 300 km (190 mi) portion of the Java coast that had been unaffected by the earlier 2004 Indian Ocean earthquake and tsunami that was off the coast of Sumatra. The July 2006 earthquake was also centered in the Indian Ocean, 180 kilometers (110 mi) from the coast of Java, and had a duration of more than three minutes.

An abnormally slow rupture at the Sunda Trench and a tsunami that was unusually strong relative to the size of the earthquake were both factors that led to it being categorized as a tsunami earthquake. Several thousand kilometers to the southeast, surges of several meters were observed in northwestern Australia, but in Java the tsunami runups (height above normal sea level) were typically 5–7 meters (16–23 ft) and resulted in the deaths of more than 600 people. Other factors may have contributed to exceptionally high peak runups of 10–21 m (33–69 ft) on the small and mostly uninhabited island of Nusa Kambangan, just to the east of the resort town of Pangandaran, where damage was heavy and a large loss of life occurred. Since the shock was felt with only moderate intensity well inland, and even less so at the shore, the surge arrived with little or no warning. Other factors contributed to the tsunami being largely undetected until it was too late, and although a tsunami watch was posted by an American tsunami warning center and a Japanese meteorological center, no information was delivered to people at the coast.

Tectonic setting

The island of Java is the most densely populated island on Earth, and is vulnerable to both large earthquakes and volcanic eruptions, due to its location near the Sunda Trench, a convergent plate boundary where the Australian tectonic plate is subducting beneath Indonesia.