Two consecutive large earthquakes eight minutes apart occurred offshore of Hengchun, Pingtung County of Taiwan at night on 26 December 2006. The seismic intensity in the Kaohsiung and Pingtung areas reached 5 according to the Central Weather Bureau's intensity scale making them the strongest earthquakes in the Hengchun area in a century. These earthquakes were felt throughout Taiwan. Because the earthquakes were located not far offshore, seismic instruments at the Taipower's Nuclear Power Plant No. 3 (NPP3) registered their largest motions since recording commenced at the site. As a result, unit 2 of NPP3 was shut down while Unit 1 remained operating at full capacity. Other damage that occurred during the Earthquake Doublet included building collapse, rock falls, structure and non-structural damage to buildings, fire, and damage to utilities such as gas, electricity, and telephone lines; liquefaction was also noted. In this paper, the shakemaps based on the source parameters and real-time observations were predicted and compared with the recorded shakemaps. This analysis shows our shakemap prediction model to be extremely useful in predicting what emergency response units can expect after a large damaging earthquake. Strong motion data near a collapsed building was used to calculate the response spectrum and compared with the building codes to check the reason of the building collapsed. This study presents the damage that occurred during this event and the results of the seismic assessment to discuss why so much damage occurred in the southern Taiwan area.