藉由刪減地震目錄中規模小於4.8之地震紀錄後，可得到較有規律的分佈，因此某些有規律之型態可能會被發現。 我們將大於4.8的事件繪於台灣地圖上，發現許多〝地震圓弧〞之現象。亦可解釋為，用特定之圓心和半徑可畫出一個圓弧，若在此弧上均勻分佈了5個點以上，其鄰近有大於4.8之事件，則稱此圓弧為地震圓弧。在台灣集集大地震發生前兩年多，即有一地震圓弧逐漸出現在台灣的中南部，我們猜測地震圓弧可能可以作為大地震之前兆，因此對過去四十二年大於4.8之地震紀錄作整體的檢視，並發現在地震弧附近常會出現大於5.8之地震。 ;The events recorded in the earthquake catalog of Taiwan are analyzed in this article. When too many events are plotted on the map of Taiwan, only disordered information is shown. However, if only the events with magnitude over 4.8 happened in a limited period of time are analyzed, some patterns with regularity can be observed. We plot the events of earthquakes with magnitudes equal to or greater than 4.8 on the map of Taiwan and find that there are many ‘‘circular arcs of earthquakes’’. That is, if we choose a radius with certain selected length and some selected center point on the map then we can draw a circular arc along which there are five or more than five position points. Around these points there are events with magnitudes . One of the remarkable arcs is that formed before the Chi-Chi earthquake in Taiwan. About a bit more than two years before that disaster there was a circular arc of events with which developed gradually in the mid-south of Taiwan. This circular arc may have a chance to be thought as a precursor of the later major earthquake. Inspired by this arc we begin to analyze the other arcs of events with in Taiwan happened in the past forty two years. In many cases we find that, after the arcs have been formed, close to the circular arcs some events with may occur.
