A New Seismic Hazard Model for New Zealand
A New Seismic Hazard Model for New Zealand
复制标题
新西兰新的地震灾害模型
DOI：
10.1785/0120010156
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发表时间：
2002
影响因子：
3
通讯作者：
K. Berryman
中科院分区：
文献类型：
--
作者：
M. Stirling;Graeme H. Mc Verry;K. Berryman
我们提出了一个新的概率地震灾害分析（PSHA）为新西兰。该分析的一个重要特点是应用了一种处理PSHA历史（分布）地震活动资料的新方法。PSHA使用全国各地和地下记录的地震活动来定义一个a -值的三维网格（即古腾堡-里希特分布的参数a log N/yr = a - bM，其中N/yr是每年在每个网格单元内记录的等于或大于M级的地震次数）；从周边地区（全国共确定14个地壳和23个地壳下地震构造带）确定参数b和古腾堡-里希特分布的极限最大截止震级，并沿地震带边界进行平滑处理。因此，该方法结合了定义地震活动性参数连续分布的现代方法（Frankel, 1995; Frankel et al., 1996）和定义大面积震源及相关地震活动性参数的传统方法（例如，Algermissen et al., 1990）。该方法提供了一种在PSHA中包含深部（俯冲带）地震活动性的方法，保留了整个地区地震活动性的细尺度空间变化，避免了传统方法中相邻区域震源包围地震活动性明显不同的区域时产生的不良边缘效应，并且还能够在区域尺度上最可靠地定义参数（参数b和古腾堡-里希特分布的最大截止震级）。和滑动式)纳入PSHA。PSHA将模拟的地震活动性数据与描述305个活动断层的位置和地震复发行为的地质数据以及专门为新西兰开发的新的峰值地面加速度和谱加速度衰减关系相结合。地壳和俯冲带地震采用不同的衰减表达式。由此得出的150年回归期的PSH图显示，在历史上地壳和深俯冲带地震活动性最高的地区，该国中部和西南部发生地震的风险最高。相比之下，更长的回归周期地图（475年和1000年的回归周期）显示，最大的危险发生在该国的西南至东北端，沿着断层容纳了太平洋和澳大利亚板块之间的大部分运动。这些地图目前正被用来修订新西兰的建筑规范，此前新西兰的建筑规范是基于psha，没有明确将单个断层列为震源。
We present a new probabilistic seismic hazard analysis (PSHA) for New Zealand. An important feature of the analysis is the application of a new method for the treatment of historical (distributed) seismicity data in PSHA. The PSHA uses the seismicity recorded across and beneath the country to define a three-dimensional grid of a -values (i.e., parameter a of a Gutenberg-Richter distribution log N/yr = a - bM , in which N /yr is the number of earthquakes per year recorded inside each grid cell equal to or greater than magnitude M ); parameter b and the limiting maximum cutoff magnitude of the Gutenberg-Richter distribution are defined from the surrounding region (14 crustal and 23 subcrustal seismotectonic zones are defined for the country) and then smoothed across the boundaries of the zones. The methodology therefore combines the modern method of defining continuous distributions of seismicity parameters (Frankel, 1995; Frankel et al. , 1996) with the traditional method of defining large area sources and the associated seismicity parameters (e.g., Algermissen et al. , 1990). The methodology provides a means of including deep (subduction zone) seismicity in a PSHA, preserves the finer-scale spatial variations of seismicity rates across a region, avoids the undesirable edge effects produced in the traditional method when adjacent area sources enclose areas of significantly different seismicity rates, and also enables parameters most reliably defined at a regional scale (parameter b and maximum cutoff magnitude of a Gutenberg-Richter distribution, and slip type) to be incorporated into the PSHA. The PSHA combines the modeled seismicity data with geological data describing the location and earthquake recurrence behavior of 305 active faults and new attenuation relationships for peak ground acceleration and spectral acceleration developed specifically for New Zealand. Different attenuation expressions are used for crustal and subduction zone earthquakes. The resulting PSH maps for a 150-year return period show the highest hazard to occur in the center and southwest of the country, in the areas of highest historical crustal and deep subduction zone seismicity. In contrast, the longer return-period maps (475 and 1000 year return period) show the highest hazard to occur from the southwest to northeast ends of the country, along the faults that accommodate the majority of the motion between the Pacific and Australian plates. The maps are currently being used to revise New Zealand's building code, which has previously been based on PSHAs that did not explicitly include individual faults as earthquake sources.
Manuscript received 10 April 2001.