Earthquakes

Because of Indonesia’s unique location of three tectonic plate meeting point, Indonesia is at a higher risk of earthquakes and tsunamis that may be caused by the earthquake. Indonesia has the fourth largest population on earth with over 260 million individuals and houses one of the most densely populated places worldwide on the island of Java. Across Indonesia the terrain is largely coastal lowlands although the larger islands have interior mountains. While Indonesia contains the most active volcanoes of any country in the world, their natural hazards also include tsunamis and earthquakes [1]. That said, much of Indonesia rests above active subduction zones. Actually, it is one of the most seismically active areas on the planet. It is surrounded by many tectonic plates including the Indo-Australia plate, the Pacific plate, the Philippine Sea plate, and the Sunda plate. It also has several faults such as Sumatra, Lembang, Sorong, and Timor. The Sumatran faulty, for example, is a large strike-slip that runs the entire length of the island of Sumatra. It ends just below the city of Banda Aceh, where a devastating earthquake and tsunami occurred in 2004. In that earthquake, Banda Aceh lost 30% of its inhabitants (>130,000), had another 7000,000 homeless, and had property losses of more than 4.4 billion dollars [2,3]. In other examples, a magnitude 6.3 earthquake near Jogjakara in 2006 had a death toll of over 6,200 with thousands more injured and more than 60,000 houses destroyed [5]. Another is the 2006 magnitude 7.7 earthquake and associated tsunami in Pangandaran, West Java. While there was only weak shaking and no ground motion damage from the earthquake, there was extensive damage and losses of over 600 lives from the tsunami. An inspection after the earthquake showed extensive damage to wooden and unreinforced masonry buildings that were located within several hundred meters of the coast [6]. Many areas of Indonesia may also be in harm’s way.

Even with above circumstances, there is little in place regarding seismic building construction safety practices and documentation. In part this may have to do with economics. The gross national income per capita in U.S. dollars is only $3,400 [4]. Regardless of income or the dollar value of structures either being built or already in place, there are steps that can be taken to improve safety. Safety of individuals should be a priority for all construction, followed secondarily but less importantly with overall building resilience.

References

[1] Central Intelligence Agency. East and Southeast Asia: Indonesia. World Fact Book, 2017.
[2] Paul Brown. Tsunami Cost Acheh a Generation and $4.4bn. The Guardian, 2005.
[3] James Sturcke. 3,500 Dead in Java Earthquake. The Guardian, 2006.
[4] World Bank Group. Indonesia. The World Bank, 2017. National Aeronautics and Space Administration. Earth Observatory, Magnitude 6.3 Quake in Central Java, 2006.
[5] Jim Mori, Walter D. Mooney, Afnimar, Sandy Kurniawan, Aan Ibnu Anaya, Sri Widiyantoro. Seismological Research Letters. The 17 July 2006 Tsunami Earthquake in West Java, Indonesia, 2007
[6] Reliefweb. Indonesia: Earthquake – Dec 2016, 2016.

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