Introduction
On March 28, 2005, the Nias Earthquake (M 8.6) struck at 2.085 degrees North, 97.108 degrees east near Sumatra, the westernmost island of Indonesia. The event lasted until about April 18, 2005.
Event Summary
The earthquake occurred along a fault between the Australian and Sunda plates, where the Australian plate is subducted beneath the Sunda plate. The northeast-oriented thrust likely occurred as a result of stress changes from the 2004 Boxing Day Earthquake (M 9.1), the focus of which was 160 kilometers northeast of the focus of the Nias Earthquake (Hayes et al., 2016). The last recorded earthquake in the same rupture point prior to 2005 occurred in 1861; studies found that the spatial extent of the two events are notably similar (Ishii, Walker, & Shearer, 2005). The event created a tsunami that was relatively tiny when compared to the waves created by the Boxing Day Earthquake that occurred nearly three months prior. Waves measuring as high as 2.3 meters were recorded in Sri Lanka three hours after the earthquake occurred. The shaking of the earthquake caused a great deal of damage and resulted in at least 1,000 fatalities (Hayes et al., 2016). The Singapore Civil Defense Force (SCDF) reported that many multi-story buildings had collapsed in the city of Gunung Sitoli, leaving hundreds trapped underneath rubble. The SCDF also noted that the people of Indonesia were just beginning to recover from the Boxing Day Earthquake, which made the Nias Earthquake even more devastating. The SCDF joined rescue efforts on March 29, 2005, providing humanitarian aid as well as assistance the the local police in road clearance and rescue operations (SCDF, 2005). In addition, emergency satellite communications were established with the help of Télécoms Sans Frontières (TSF), an emergency relief organization (TSF, 2019).
Discussion
The unfortunate timing of the 2005 Nias Earthquake in relation to the devastating 2004 Boxing Day Earthquake cannot be understated. The proximity between the two events meant that the recovery efforts that had recently begun were interrupted in response to a major earthquake. Moreover, it is important to acknowledge that the communities hit by the 2004 earthquake were most likely traumatized by the event, so a disaster of similar type certainly would have worsened morale and mental health in Indonesia and surrounding areas. On the note of how close together the two events occurred, it is prudent to think about how the devastating 2004 earthquake may have contributed to the one in 2005. If an earthquake similar to the Boxing Day event hits a region, then perhaps the affected area should anticipate possible sequential events as they recover and rebuild. Looking at the paleoseismology of an area could help determine if these "after-events" might happen, which may better inform the reconstruction process. While the structure of the multi-story buildings in Gunung Sitoli is unknown, it is likely they were not built to withstand earthquakes if they collapsed and trapped people underneath rubble. New structures made of concrete and old structures retrofitted for earthquakes would prevent as many casualties; building collapse is the leading cause of earthquake fatalities. Given that southeast Asia has been seismically active throughout its history, it is safe to say that communities should anticipate frequent and major earthquakes throughout their lifetime, even major earthquakes that occur in spots that are close to each other and time spans that are quite small. As a result, more funding should be allotted to aid organizations like the SDCF and the TSF, so that they are better equipped to help when disasters inevitably arise in the region.
Pictures
Distribution of aftershocks post-March 28, 2005.
Aerials and ground shots from island hit by quake - Associated Press Archive
Sources
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