Seismic-Hazard Maps for Alaska and the Aleutian Islands: PGA050

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 peak horizontal acceleration with a 10% 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.

针对阿拉斯加州编制了多套概率地震危险性图（Probabilistic Seismic Hazard Maps），涵盖0.2s、0.3s及1.0s周期下的水平峰值地面加速度（peak horizontal ground acceleration）与水平谱响应加速度（horizontal spectral response acceleration），对应50年超越概率分别为10%与2%。本次提供的特定数据集，对应50年超越概率10%的水平峰值地面加速度。所有地震危险性图均通过融合空间平滑历史地震活动性（spatially-smoothed historic seismicity）得到的危险性，与特定震源断层（fault-specific sources）得到的危险性共同编制完成。所绘等值线对应的加速度值为随机水平分量。参考场地条件设定为坚硬岩石，定义为地表30米范围内平均剪切波速（shear-wave velocity）达760 m/s，对应美国国家地震灾害减轻计划（NEHRP）场地类别B与C的分界标准。
本数据集基于经纬度间距均为0.1°的网格点危险性曲线（hazard curves）计算结果生成。通过对该网格点数据绘制等值线，得到最终的地震危险性可视化成果。