Unfortunately, most of the island is made of sedimentary rock. Mount Chiuchiu in Shuangtung, which stands 400 to 500 meters high, is a loose mix of boulders and gravel that is especially vulnerable to the effects of an earthquake. In the words of geology professor Wang Hsin: "Just give it a good shake and it'll come crashing down."
四、五百公尺的雙冬九九峰，正是老河床堆積的沈積層，大石頭夾小石頭的體質，被地理教授形容為「一抖就散」。