The Alhama de Murcia Fault is one of the main active structures of the Eastern Betic Shear Zone (SE Spain), characterized by the presence, along its trace, of Neogene basins developed under Early to Late Miocene extensional tectonics. A dominant NNW‐SSE shortening direction is active from Late Miocene driven by the present‐day plate convergence. We present the structural analysis of the northeastern section of this fault, where reliable estimations of slip rates were unknown due to the lack of geomorphological evidence of recent activity. The recent tectonic evolution and reactivation of the northeastern section is closely related to the Fortuna basin development and tectonic inversion. We approach the structural analysis through the interpretation of seismic reflection profiles, well data, fieldwork and 3D geological modeling. We estimated a maximum long‐term slip‐rate of (0.32 +0.18/‐0.13) mm/yr in the Librilla sector (last 4.8‐7.6 Ma), based on cross‐section restorations and assuming current motion trends from GPS data. According to the results from the cross‐sections restored along the section and a vertical displacement analysis based on a 3D model, the slip‐rate distribution shows a decrease of activity toward the northeastern tip of the studied fault section. This supports a transference of deformation between the Alhama de Murcia Fault and the Carrascoy Fault, which seems to absorb part of the shortening during the Plio‐Quaternary, explaining the lower relief created by the activity of the northeastern section. The slip rates obtained have important implications in seismic hazard assessments and in the distribution of deformation along the region.

中文翻译：

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Alhama de Murcia 断层（西班牙东南部贝蒂克剪切带）北端的新近系盆地反转和近期滑动速率分布

Alhama de Murcia 断层是东贝蒂克剪切带（西班牙东南部）的主要活动构造之一，其特征是沿其踪迹存在在早中新世伸展构造下发育的新近纪盆地。在现今板块辐合的驱动下，一个主要的 NNW-SSE 缩短方向从晚中新世开始活跃。我们介绍了该断层东北部的结构分析，由于缺乏近期活动的地貌证据，因此对滑动率的可靠估计是未知的。近期东北段构造演化和再活化与福尔图纳盆地发育和构造反转密切相关。我们通过地震反射剖面的解释、井数据、现场工作和 3D 地质建模来进行结构分析。我们基于横截面恢复并假设来自 GPS 数据的当前运动趋势，估计了 Librilla 扇区（最近 4.8-7.6 Ma）的最大长期滑移率（0.32 +0.18/-0.13）mm/yr。根据沿该断面恢复的断面和基于 3D 模型的垂直位移分析的结果，滑移率分布显示向所研究断层东北端的活动减少。这支持了 Alhama de Murcia 断层和 Carrascoy 断层之间的变形转移，这似乎吸收了上新-第四纪期间的部分缩短，解释了由东北部分的活动造成的较低的起伏。获得的滑移率对地震危险性评估和沿该地区的变形分布具有重要意义。