Ground-Motion Attenuation Equations for Earthquakes on the Cascadia Subduction Zone
Ground-Motion Attenuation Equations for Earthquakes on the Cascadia Subduction Zone
复制标题
卡斯卡迪亚俯冲带地震的地面运动衰减方程
DOI：
10.1193/1.1585626
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发表时间：
1991
影响因子：
5
通讯作者：
C. B. Crouse
中科院分区：
文献类型：
--
作者：
C. B. Crouse
一个广泛的地面运动数据库被编译为发生在俯冲带地震被认为是在太平洋西北部的卡斯卡迪亚俯冲带的代表。研究了水平峰值地面加速度（PGA）和5%阻尼拟速度（PSV）在总数据库的不同子集上的衰减特性。这些数据表明，PGA往往饱和在小源到站点的距离和大的幅度。当未处理的数据被添加到数据库中时，PGA随距离的衰减被发现大于仅对处理的数据观察到的衰减，这是由于仅选择较强的运动记录进行处理的结果。数据分析的结果被用来建立适当形式的回归方程估计PGA和PSV在坚实的土壤网站在太平洋西北地区。共选择697个PGA组件和235个PSV组件进行回归分析。计算PGA的公式为ln（PGA）= 6.36 + 1.76 M − 2.73 ln（R + 1.58 exp（0.608 M）+0.00916 h，σ=0.773其中M为矩等，R为能量释放中心距离，h为震源深度，单位为km，σ为ln（PGA）的标准误差。虽然σ相对较大，但回归的残差似乎随着M和R的增加而减少。PSV回归的结果表明，M系数和f（R，M）衰减项的系数一般随周期的增加而增加，这与其他文献报道的回归结果一致。回归方程在预测1949年和1965年普吉特海湾地震期间在奥林匹亚和西雅图、华盛顿记录的加速度记录的反应谱时相当准确，但在后一次地震期间高估了在塔科马和波特兰记录的较弱运动的反应谱。由这些方程预测的华盛顿海岸山脉场地的中值反应谱与希顿和Hartzell根据太平洋西北部假想大地震（M = 9.0和9.5）的地面运动模拟计算的反应谱相似。
An extensive ground-motion data base was compiled for earthquakes occurring in subduction zones considered representative of the Cascadia subduction zone in the Pacific Northwest. The attenuation characteristics of horizontal peak ground accelerations (PGA) and 5 percent damped pseudovelocity (PSV) were studied for various subsets of the total data base. These data suggested that the PGA tend to saturate at small source-to-site distances and large magnitudes. When unprocessed data were added to the data base, the attenuation of PGA with distance was found to be greater than the attenuation observed for the processed data only, a result which was attributed to the selection of only the stronger motion records for processing. The results of the data analysis were used to establish the proper form of regression equations for estimating PGA and PSV at firm-soil sites in the Pacific Northwest. A total of 697 PGA components and 235 PSV components were selected for the regressions. The resulting equation for estimating PGA in gals was ln (PGA) = 6.36 + 1.76M − 2.73 ln (R + 1.58 exp (0.608M) + 0.00916h, σ=0.773 where M is moment magnitude, R is center-of-energy-release distance in km, h is focal depth in km, and σ is the standard error of ln (PGA). Although σ was relatively large, the residuals from the regressions appeared to decrease with increasing M and R. The results of the PSV regressions showed that the M coefficient and the coefficient of the f(R, M) attenuation term generally increased with period, which is consistent with regression results reported by others. The regression equations were reasonably accurate in predicting the response spectra of accelerograms recorded at Olympia and Seattle, Washington during the 1949 and 1965 Puget Sound earthquakes, but overestimated the spectra of the weaker motions recorded at Tacoma and Portland during the latter event. The median response spectra predicted by these equations for a Washington Coastal Ranges site were similar to the spectra computed by Heaton and Hartzell based on their simulations of ground motions from hypothetical giant earthquakes (M = 9.0 and 9.5) in the Pacific Northwest.