December 2004 Earhquake in Northern Sumatra, Indonesia

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The December 2004 Earthquake in Northern Sumatra, Indonesia

Sarah Loiacano

November 16, 2010

Geology Section H004

On December 26, 2004, mass destruction and devastation was the result of a large earthquake off of the West Coast of Northern Sumatra, Indonesia. The earthquake began in the early morning on Sunday at 7:58:53 AM, and wreaked havoc on thousands in the affected areas. BBC News reported on the earthquake, stating that “Sunday’s tremor – the fourth largest since 1990 – had a particularly widespread effect because it seems to have taken place just below the surface of the ocean, analysts say” (BBC News). The earthquake had significant effect on the region and the people living in these regions. Not only was the earthquake damaging and devastating, but the quake was also the cause of a correlated tsunami that caused even more damage and destruction to the area. “This earthquake is the largest event in the world in 40 years, and produced the most devastating tsunami recorded in history” (Lay). “Coastal communities across South Asia – and more than 4,000 km away in Africa – were swept away and homes engulfed by waves up to 10 m high after the quake created a tsunami that sped across the ocean” (BBC News).

The geographic location of the Earthquake in absolute location is 3.316˚North, 95.854˚East; and the relative location of the quake was off the West Coast of Northern Sumatra, which was 155 miles South Southeast of Banda Aceh, Sumatra Indonesia, and 185 miles West of Medan, Sumatra, Indonesia (USGS). The earthquake that shook the West of Northern Sumatra, Indonesia, as well as many other neighboring countries, was of a great 9.0 magnitude on the Richter scale. “At the source of the earthquake, the interface between the India plate and the Burma plate dips about 10 degrees to the east-northeast. The subducting plate dips more steeply at greater depths”(USGS). The quake occurred when the Earth’s crust, a 1,200 km segment of the crust, shifted beneath the Indian Ocean, as far as 10 to 20 meters below (Marshall). As the crust shifted and the quake went into motion, a substantial amount of energy was released. Energy released by this overwhelming earthquake was an “estimated 20X10^17 Joules, or 475,000 kilotons (475 megatons) of TNT, or the equivalent of 23,000 Nagasaki bombs” (Marshall). All of this stored elastic energy that was released by the earthquake, in turn initiated the” uplift of the seafloor and the displacement of billions of gallons of seawater” (Marshall). These events lead to a massive tsunami. “Over a period of 10 hours, the tsunami triggered by the quake struck the coasts of over 12 countries” (Marshall).

“The region where the great earthquake occurred on 26 December 2004, marks the seismic boundary formed by the movement of the Indo-Australian plate as it collides with the Burma subplate, which is part of the Eurasian plate” (Pararas-Carayannis). “For millions of years the India tectonic plate has drifted and moved in a north/northeast direction, colliding with the Eurasian tectonic plate and forming the Himalayan Mountains. As a result of such migration and collision with both the Eurasian and the Australian tectonic plates, the Indian plate’s eastern boundary is a diffuse zone of seismicity and deformation, characterized by the extensive faulting and numerous large earthquakes” (Pararas-Carayannis). “Previous major earthquakes have occurred further north, in the Andaman Sea and further South along the Sumatra, Java and Sunda section of one of the earth’s greatest fault zones, a subduction zone known as the Sunda Trench. Slippage and plate subduction make this region highly seismic” (Pararas-Carayannis). “In addition to the Sunda Trench, the Sumatra Fault is responsible for seismic activity on the Island of Sumatra. This is a strike-slip type of fault which extends along the entire length of the island” (Pararas-Carayannis). East of northwest Sumatra, “a divergent plate boundary...
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