在地震相關研究中，Gutenberg與Richter兩位學者提出討論地震頻率與地震規模的G-R關係logN = a - bM，其中b值反映大小地震之間的比例關係。b值隨著研究區域內的地質分布、地體構造、地溫與應力形式等條件不同而有所變化。本研究利用中央氣象局地震觀測網(CWBSN)的豐富地震資料來探討台灣地區淺層地震b值在空間、時間與深度的特性，及集集大地震前後b值的變化。
研究結果顯示：b值在空間上變化顯著，台灣中北部b值較大(約1.17)而東部較小(約0.79)；其結果與由GPS地殼變形監測所得的台灣地區年應變率相呼應，可發現高b值區其年應變率通常較小，低b值區其年應變率較大。顯示應變累積較大的地區其岩層中亦累積較大應力，因而呈現較低的b值。b值在深度的變化，在中部地區下地殼(20~35公里)b值比上地殼(0~20公里)b值小，而在大部分區域淺部上地殼(0~10公里)b值小於深部上地殼(10~20公里)。
集集大地震前後的b值變化，在15公里上下之深度，集集震央所在區域觀察到震前b值顯著變小(約0.65)，而在震中升至0.85，震後b值更增至1.15。這意味著集集大地震發生前在此深度累積了較大的地殼應力，而由車籠埔斷層錯動釋放區域內之應力。此深度是該區地體構造上主滑脫面的位置，在集集大地震餘震序列中主滑脫面的大量地震活動，使得累積應力獲得釋放。集集震央的鄰近區域，在震前b值都較大(約1.5~1.8)，震中b值大幅變小(約0.9)，震後則漸回升(約1.2)；這顯示在震前鄰近震央的區域此深度雖未累積大量的應力，但因集集大地震造成應力系統平衡的破壞，地殼應力分布狀態重新調整，進而引起鄰近區域的應力系統也隨之改變。
在規模較大(ML>6)的地震事件發生前，震央所在的區域或其鄰近區域在時間序列中大都沒有出現b值減小與小地震數量減少的顯著變化；顯示目前仍無法有效地運用b值在大地震發生前的變化來做為地震前兆指標。

The b-value of the frequency-magnitude relation, introduced by Gutenberg and Richter in 1944, is well known to be a proper index to reflect the ratio of large and small earthquakes on some region. A number of factors have been identified to be important to the b-values. These factors include geological structure, tectonic regimes, geothermal gradient, and stress level. In this study, the earthquake catalogs established by Central Weather Bureau Seismic Network (CWBSN) are used to estimate the b-values of shallow earthquakes in Taiwan, and to discuss the characters of the b-values as a function of locations, time, and depths, respectively. Another purpose of this research is to discuss the variation of b-values before- and after- the Chi-Chi earthquake.
The results show the b-values of middle and northern Taiwan are considerably higher than those of eastern Taiwan, and this is conformed with the GPS observations on the strain rate field in the Taiwan regions. It is seemed to show that there is larger stress in the rock formations where with larger strain accumulation, and then the lower b-values. For the issue of depth, the research results show in Central range, the b-values of lower crust (about 20 to 35 kilometers) are lower than of upper crust (0 to 20 kilometers). However, in most areas of Taiwan, the b-values of the depth between 0 and 10 kilometers are lower than of the depth between 10 and 20 kilometers.
At depth of about 15 kilometers and in the seismogenic zones of the epicenter of Chi-Chi earthquake, it is observed that b-values are quite low before the earthquake and then increased in and after the earthquake gradually. It is seemed to show before the Chi-Chi earthquake, there was larger stress accumulation at depth. When the Chelungpu fault was active, this stress was then released. It is noted that this depth is the location of decollement of these areas, so the accumulated stress can be released during aftershocks of Chi-Chi earthquake. On the other hand, near these seismogenic zones, the variations of b-values are different. Before Chi-Chi b-values are higher, during Chi-Chi, b-values are decreasing substantially, and after Chi-Chi b-values are then increasing gradually. This phenomenon shows although these areas did not accumulate considerable strain energy before Chi-Chi earthquake, this earthquake is so violent that it broke the equilibrium of stress system. The stress distribution of the crust will adjust, and it reflects the stress system of these areas.
The results of this study also show that before a large earthquake, there are no phenomena like b-values being decreasing or amount of small earthquakes being decreasing happened in the seismogenic zones of the epicenter or the nearby areas. This seemed that the variation of b-values in time series is still not a earthquake precursor.

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