Model Answer : Indonesia’s explosive geology.

The archipelago has been marred with constant earthquakes and tsunamis. What are the reasons behind Indonesia’s explosive geology?

• The location of Indonesia is unique which is responsible for making it susceptible to frequent tremors. Its position on grid of active tectonic plates make it prone to earthquakes
• Indonesia is located at the meeting point of three major continental plates, the Pacific, the Eurasian and the Indo-Australian plates – and the much smaller Philippine plate.
• The plates are in constant motion and grind against each other. When two or more plates strike, they create pressure and it leads to a release of a lot of energy in the form of tremors.
• It also falls on the “ring of fire” (also known as the Circum-Pacific Belt) around the edges of the Pacific Ocean. This ring is in the shape of a horseshoe and passes through the coasts of Asia and the Americas.
• The areas along this ring are most prone to earthquakes because they lie on the boundaries of two colliding tectonic plates, i.e. the subduction zone.
• Tectonic plates on an average move only a few centimeters every year. But in cases where an earthquake strikes, they can move to several meters per second.
• The plates are constantly moving and the movement results into various physiological features like ocean trenches and phenomenon like volcanic eruptions.
• The country covers many complex tectonic environments. For example, Eastern Indonesia has many small microplates, which are jostled around by the motion of large Australia, Sunda, Pacific, and the Philippine Sea plates.
• Indonesian population tends to live-in low-lying areas close to the coast. This puts them closer to coasts and at a greater risk of Tsunami.
• A tsunami is a series of sea waves generated by an earthquake under the sea. The average height of a tsunami is 5 meters or even more.
• The Indonesian coastline is accentuated in the eastern part. For considering a tsunami, the depth and the shape of a seafloor are important factors to be considered. Narrow, deep and long bays are at the risk of experiencing more devastating tsunamis.
• Indonesia is situated in the Alpin belt region, another reason for Indonesia being prone to volcanoes. This is a seismic and an orogenic belt that includes a range of mountains extending from Java to Sumatra via the Himalayas to the Mediterranean and into the Atlantic. This belt is created by the ongoing plate tectonics, in this case, alpine orogeny and is the second most seismically active region of the world.