Case Study 1: 2004 Sumatran Earthquake

The Boxing Day 2004 Earthquake: A Holiday's Worst Nightmare

In order to explore what a tsunami is and how tsunamis are formed, we will use the 2004 Sumatran Tsunami to illustrate exactly how earthquake events can produce such destructive outcomes. You will rely on topics covered in Unit 1 (modules 2 and 3) to help understand the plate tectonics responsible for earthquake activity, but we will use the USGS's Pacific Coastal and Marine Science Center's website to explore the specific geologic details that gave rise to the tsunami. The day after Christmas (December 26, 2004), a large magnitude earthquake occurred just west of the island of Sumatra along a subduction boundary between two tectonic plates. The date couldn't be worse for such an event to occur, with thousands of people on holiday in the region and with very few people working in government offices, it was a recipe for disaster. Tourists from all over the world were vacationing in seaside resorts in Thailand, Indonesia, India, and elsewhere. Unplugged as they were, it was next to impossible to inform them or the residents of the region of the impending hazard once the earthquake and tsunami were detected. The result was that over 150,000 people lost their lives. But how? Let's take some time and work through a series of questions whose answers can be found on the website.

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Figure 5.31: Screen capture from the USGS. Lampuuk on the island of Sumatra before and after the Banda Aceh earthquake on Boxing Day, 2004 (December 26, 2004). Lampuuk is located on the northwestern most peninsula of the island. The image on the left shows the area prior to the tsunami and, on the right, the area after the tsunami. Tsunami waves swept from west to east across this region in complex patterns. Significant infrastructure including roads, agricultural areas, residential and beach front areas were obliterated during this event. Moreover, significant erosion pushed the shoreline inland and resulted in subsidence that contributed to continued land loss after the tsunami.
Credit: USGS: Tsunamis and Earthquakes

• Summary of 2004 Sumatran Earthquake