若一均質物體其內部性質會隨著方向變化而改變，此物體便具有非均向性。當剪切波經過非均向介質時將會分離為傳遞速度不同且粒子運動方向互相垂直的二波：傳遞速度較快者為快S波，較慢者稱為慢S波。快S波的粒子運動方向稱為極化方向 (ψ) ，代表非均向體內部物質排列的方向；快波與慢波之間的延遲時間差 (δt) 則反映傳遞路徑內非均向性的強度或非均向層之厚度。當區域應力場改變方向或應力強度時，地殼內部的裂隙排列會隨之變化。利用分析S波分離觀察地殼的非均向性可以直接反映地下裂隙的方向與強度，有助於了解地殼內部的應力表現。
本研究於2003年4月至6月間在臺灣西南部嘉義地區設置八部臨時寬頻地震儀，為三分量速度形連續紀錄，配合氣象局之地震目錄選取地震，再利用波形交互比對法 (waveform cross-correlation method) 求得研究區域之快S波極化方向與延遲時間解。
研究結果顯示，研究地區快S波的極化方向多與地表活動斷層走向及地層走向平行，而由於設站期間較短，延遲時間隨日期則無明顯的變化情形；而極化方向與延遲時間在兩相鄰測站CK06與CK08東西兩側呈現不一致的情形，西側區域有較多的破裂及活動斷層，延遲時間差較長，極化方向結果較為複雜，非均向程度較強；東側地質環境較西側單純，極化方向結果較為單一，延遲時間較短。

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