Seismic attenuation across the US is estimated using station ML magnitude data from the USArray. Station magnitudes are recalibrated back to amplitude and back projected in a two-dimensional tomography. Data represent the amplitudes of the horizontal components of the Lg phase. The western US shows regions of very high attenuation and contrasts with the lesser attenuation of the eastern US. Individual attenuation anomalies can be clearly tied to regional geology. Station gains show broad regional variations that match geographic regions. Most of the high attenuation areas are regions of high geothermal activity suggesting that intrinsic attenuation dominates over scattering attenuation. An exception is the central San Andreas Fault zone because it lacks any localized heat-flow anomaly. The US east of the Rocky Mountains is bland and contains none of the high attenuation regions of the western US. Instead the central US has low attenuation patches that do not obviously correspond to geologic province. Sediments of the Gulf Coast Plain, Willison Basin, and Michigan Basin do show up as intermediate attenuation while the Illinois Basin, Appalachian Basin, and other basins are not apparent. In Alaska, attenuation is generally less than the western US, but still much greater than the eastern US. In southeast Alaska, the Wrangell Volcanic Field causes a sizeable high attenuation zone. The volcanic Aleutian Mountains also have high attenuation. However, moderate to high attenuation also correlates with the tertiary sedimentary basins in Alaska. The North Slope Basin does not seem to attenuate. Thicker crust and mountain roots tend to show less attenuation, if anything, but this correspondence is most likely due to differences in temperature and seismic velocity. Heat, scattering, and young sedimentary basins create seismic attenuation in the continental crust.

中文翻译：

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USArray ML振幅层析成像的地壳衰减

美国境内的地震衰减是使用USArray的ML震级数据估算的。站幅值将重新校准回振幅，并在二维层析X射线照相术中反向投影。数据表示Lg相的水平分量的幅度。美国西部的衰减区域非常高，而美国东部的衰减较小。各个衰减异常可以明确地与区域地质联系在一起。台站增益显示出与地理区域相匹配的广泛区域差异。大多数高衰减区域是地热活动高的区域，这表明固有衰减在散射衰减上占主导地位。一个例外是中心的圣安德烈亚斯断层带，因为它没有任何局部的热流异常。落基山脉以东的美国是乏味的地区，不包含美国西部的高衰减区域。取而代之的是，美国中部具有低衰减斑块，显然与地质省份不符。墨西哥湾沿岸平原，威利森盆地和密歇根盆地的沉积物确实表现为中等衰减，而伊利诺伊斯盆地，阿巴拉契亚盆地和其他盆地则不明显。在阿拉斯加，衰减通常小于美国西部，但仍远大于美国东部。在阿拉斯加东南部，弗兰格尔火山场造成了相当大的高衰减带。火山阿留申山脉也有很高的衰减。但是，中度到高度衰减也与阿拉斯加的第三纪沉积盆地有关。北坡盆地似乎没有衰减。厚的地壳和山根趋向于表现出较小的衰减（如果有的话），但是这种对应关系很可能是由于温度和地震速度的差异所致。热，散射和年轻的沉积盆地在大陆壳中造成地震衰减。