[Name of the Writer]

[Name of the Supervisor]

[Subject]

[Date]

Earthquake: Sumatra Indonesia

Introduction

The earthquake in the Indian Ocean of magnitude 9.1 on the Richter scale, the hypocenter was located about 30 km beneath the Indian Ocean off the west coast of northern Sumatra and 250 km southeast of Banda Aceh. The main shock occurred December 26 2004 at 1:58:53 Warsaw time (0:58:53 UTC, 7:58:53 local time in Jakarta and Bangkok). According to seismologists, it was the fourth in terms of earthquake forces since 1900, since this leads to continuous seismic observations. The earthquake triggered waves of tsunami, which in three hours hit the coast of several countries of Southeast Asia and later Africa, reaching 15 m waves devastated coastal villages and towns, as well as spa visit at this time of year for foreign tourists.

The greatest damage caused by the tsunami on the coast of Indonesia (province of Aceh ), Sri Lanka and India (the state of Tamil Nadu , Andhra Pradesh and in the archipelagos Andaman and Nicobar Islands ) and Thailand (including the island of Phuket). Minor damage reported in Malaysia, Myanmar, the Maldives, Seychelles and Somalia. According to the balance sheet published by the AFP (of 6 February 2005) the number of dead and missing at least 294 000 people and this is not the final balance of the tragedy, leaving several million homeless (Marshall, pp. 1).

Location of seismic wave sources and aftershocks

Initially, the shock strength was evaluated at 6.8 degree on Richter scale. However, for such a powerful earthquake is more appropriate to the administration of the seismic moment magnitude, which is initially calculated at 8.1 (USGS) to later revise its value to 8.5, then to 8.9. Finally, seismologists gave a value magnitude 9.0. It was therefore the strongest earthquake for nearly 40 years. Since the year 1900, since carried out regular observations of seismic shocks recorded, only four of greater magnitude. Some of these were also the source of the tsunamis, but the number of their victims not to exceed one thousand. Hypocenter was located west of Sumatra, 30 km below sea level. This area is part of the Pacific Ring of Fire, an area very active seismically. Seismic waves were felt in Bangladesh, India, Malaysia, Myanmar, Singapore, Thailand and the Maldives. Remarkable was the extent of the area generating shocks. According to estimates of 1200 km earthquake fault slipped about 15 meters to the zone of subduction, where the Indian plate is immersed under the Burmese Plate. The sea bed sheets Burmese rose about 10 meters. This movement was a source of shock waves at a speed of 800 km / h, which after reaching the coast turned into a deadly tsunami waves.

Geological Inference

The devastating power of the 2004 earthquake in Sumatra-Andaman was due largely to a mass of compact sediments and thicker than normal.

The tectonic plates near the epicenter

Indian plate is part of larger tectonic plates, which forms the boundaries of the Indian Ocean and Bay of Bengal. The whole is moving toward the northeast ...