We image seismic properties of the plate boundary through northern Baja California and southernmost California using a double-difference tomography and earthquake relocation algorithm that incorporates both event-pair and station-pair data. The data are derived from seismic networks in southern California (SCSN) and northern Baja California (CICESE). It comprises >700,000 travel times (P and S) associated with ∼200 seismic stations and >21,000 local earthquakes from 2003-2018, along with >2,000,000 event-pair and >1,500,000 station-pair double-differences derived from these travel times. In the upper crust, low V_P values in the resultant models imply deep sediments and sedimentary rocks northwest of the Salton Sea and around the northern end of the Imperial fault. Low V_S values indicate regions of rock damage at the northern ends of the Sierra Juarez fault zone and Laguna Salada fault, and the southern end of the San Jacinto fault zone (SJFZ). Shallow seismicity (d${}_{95}<6$ km) highlights the Salton Buttes and Cerro Prieto volcanoes as high heat-flow thin crust regions. At mid to lower crustal depths, the sharpest contrast in crustal V_P and most prominent low V_S anomaly (V${}_S\sim 3.4$ km/s, V_P/V_S ∼ 1.9) occurs along a corridor extending northwestward from the Cerro Prieto fault (CPF), east of and subparallel to the Sierra El Mayor/Cucapah and into the southern SJFZ, indicating a continuous weak fluid-rich zone. At ∼25 km depth, we observe uppermost mantle velocities (V${}_P\sim 7.8$ km/s) in the eastern Salton Trough, crustal velocities (V${}_P<7$ km/s) around the Sierra El Mayor/Cucapah and Peninsular Ranges, and near mantle velocities (7.4 < V_P < 7.8 km/s) beneath Laguna Salada. These results illuminate a thin crust in the Salton Trough, except for the Sierra El Mayor/Cucapah, and a thicker crust in the Peninsular Ranges. In all, high seismic activity, rapid changes in crustal structure and the prevalence of damage/deformation and fluids in a corridor extending from the CPF to the southern SJFZ emphasize this zone as a key component of the active plate boundary.

我们使用双差断层扫描和地震重定位算法对穿过下加利福尼亚州北部和加利福尼亚州最南端的板块边界的地震特性进行成像，该算法结合了事件对和站对数据。这些数据来自加利福尼亚南部 (SCSN) 和下加利福尼亚北部 (CICESE) 的地震网络。它包括与 2003 年至 2018 年间约 200 个地震台站和 >21,000 次局部地震相关的 >700,000 个旅行时间（P 和 S），以及从这些旅行时间得出的 >2,000,000 个事件对和 >1,500,000 个站点对双差。在上地壳中，所得模型中的低 V _P值意味着索尔顿海西北部和帝国断层北端附近的深层沉积物和沉积岩。低V_小号数值表示 Sierra Juarez 断层带和 Laguna Salada 断层北端以及圣哈辛托断层带 (SJFZ) 南端的岩石损坏区域。浅层地震活动（d${}_{95}<6$km) 突出了索尔顿山和塞罗普列托火山作为高热流薄壳区域。在中下地壳深度，地壳 V _P反差最明显，V _S低异常（V${}_{秒}～3.4$km/s, V _P /V _S ∼ 1.9) 沿一条从 Cerro Prieto 断层 (CPF) 向西北延伸、在 Sierra El Mayor/Cucapah 以东并与其平行并进入 SJFZ 南部的走廊发生，表明持续的弱流体 -富人区。在大约 25 公里的深度，我们观察到最高地幔速度（V${}_{磷}～7.8$ km/s) 在东索尔顿海槽，地壳速度 (V${}_{磷}<7$km/s) 在 Sierra El Mayor/Cucapah 和半岛山脉附近，以及Laguna Salada 下接近地幔速度 (7.4 < V _P < 7.8 km/s)。这些结果说明了索尔顿海槽中的薄地壳（除了 Sierra El Mayor/Cucapah）和半岛山脉中的厚地壳。总而言之，高地震活动、地壳结构的快速变化以及从 CPF 延伸到 SJFZ 南部的走廊中的损坏/变形和流体的普遍存在强调了该区域是活动板块边界的关键组成部分。