Seismic-Hazard Maps for Alaska and the Aleutian Islands: 3HZ250

Probabilistic seismic hazard maps were prepared for Alaska portraying
peak horizontal ground acceleration and horizontal spectral response
acceleration for 0.2, 0.3, and 1.0 second periods with probabilities
of exceedance of 10% in 50 years and 2% in 50 years. This particular
data set is for horizontal spectral response acceleration for 0.3 second
period with a 2% probability of exceedance in 50 years. All of
the maps were prepared by combining hazard derived from spatially-
smoothed historic seismicity with hazard from fault-specific sources.
The acceleration values contoured are the random horizontal component.
The reference site condition is firm rock, defined as having an average
shear-wave velocity of 760 m/sec in the top 30 meters corresponding to
the boundary between NEHRP site classes B and C.
This data set represents the results of calculations of hazard curves
for a grid of points with a spacing of 0.1 degrees in latitude and
longitude. The grid of points were contoured to produce the final
representation of the seismic-hazard.

本数据集针对阿拉斯加地区编制了概率地震危险性图（Probabilistic Seismic Hazard Maps），展示了50年基准期内超越概率分别为10%、2%时，周期为0.2秒、0.3秒及1.0秒的水平向峰值地面加速度（Peak Horizontal Ground Acceleration）与水平向频谱响应加速度（Horizontal Spectral Response Acceleration）的分布情况。本次特定数据集对应周期为0.3秒、50年基准期内超越概率2%的水平向频谱响应加速度结果。所有危险性图均通过融合两类震源危险性成果编制而成：一类是基于空间平滑化历史地震活动性（Spatially-smoothed Historic Seismicity）推导得到的危险性，另一类则来自特定断层震源（Fault-specific Sources）的危险性贡献。所绘制等值线对应的加速度值为随机水平分量（Random Horizontal Component）。参考场地条件设定为坚硬岩石（Firm Rock），其定义为地表30米范围内平均剪切波速达760米/秒，对应美国国家地震减灾规划（NEHRP）场地类别B与C的分界标准。本数据集涵盖了经纬度间隔为0.1°的网格点危险性计算结果，通过对该网格点数据进行等值线绘制，最终得到地震危险性的可视化表达成果。