Possible Connections Between a Great Earthquake and an Earthquake Sequence: Samoa Islands (8.1) and Vanuatu Islands

Dynamic triggering describes the possibility that certain earthquakes cause, or ‘trigger’ new earthquakes at great distances. Static triggering is common and is known to cause aftershocks very near to the site, generally within two lengths of the ruptured fault. Dynamically triggered events can occur at distances beyond two fault lengths, however the mechanism for how this can occur remains unknown. By examining seismic data collected from possible dynamically triggered events, we may gain a better understanding of the mechanisms at work. On September 29, 2009, an earthquake of magnitude 8.1 took place along a 175 km fault rupture in Samoa, an island along the Tonga Trench in South Pacific Ocean. A week later a string of earthquakes occurred over 2000 km away, well beyond the bounds for static triggering, on Vanuatu Island in the South Pacific. Utilizing the USGS and Global CMT website yielded seismic data including magnitude, depth, and location that were plotted and mapped to investigate these earthquake events. Future research aims to analyze this data more thoroughly, as well as compare it to accepted instances of dynamic triggering in the hopes of determining if the Samoa earthquake is an example of dynamic triggering