Map Sheet 48 (2025 update) - Ground Motion from PGA (2% in 50 years)

This image service is part of a collection of maps for PGA, PGV and spectral accelerations at 0.2 s (SA02), 1.0 s (SA10), and 2.0 s (SA20) to illustrate seismic hazards in California. For each ground motion parameter, maps at two different hazard levels were presented: one with a 2% probability of being exceeded in 50 years (equivalent to 2,475-year recurrence interval) and the other with 10% probability of being exceeded in 50 years (equivalent to 475-year recurrence interval). The ArcGIS Online interface allows users to select any two ground motion hazard maps to compare side by side. Ground motion parameters were calculated using the 2023 update of the U.S. Geological Survey National Seismic Hazard Model. See the “Scientific Background” on MS48 webpage for detailed information. Due to software limitations, symbology cannot be added to this service. To match the symbology used in the MS48 Ground Motion application, use the following configuration: Esri Color Ramp: Magma Minimum: 4.41 g Maximum: 0.032 g Gamma: 1本影像服务隶属于一套用于展示加利福尼亚州地震危险性的地图集，涵盖峰值地面加速度（Peak Ground Acceleration, PGA）、峰值地面速度（Peak Ground Velocity, PGV）以及周期为0.2 s（SA02）、1.0 s（SA10）和2.0 s（SA20）的谱加速度数据。针对每一类地面运动参数，本数据集提供了两种不同危险性水准的地图：一种为50年内超越概率2%（对应重现期2475年），另一种为50年内超越概率10%（对应重现期475年）。ArcGIS Online界面支持用户选取任意两个地面运动参数对应的地图进行并排对比。地面运动参数系基于美国地质调查局（U.S. Geological Survey, USGS）2023年更新版的全国地震危险性模型计算得到。详细信息请参阅MS48网页上的“科学背景”板块。受软件限制，本服务无法添加符号系统（symbology）。若要匹配MS48地面运动应用中使用的符号系统，请采用如下配置：Esri色带（Esri Color Ramp）：Magma；最小值：4.41 g；最大值：0.032 g；伽马值（Gamma）：1。