Abstract On August 24th 2016, a Mw 6.0 earthquake started the Amatrice - Norcia (Central Italy) seismic sequence, generated by the extensional tectonics along the Apennines, that had its apex with the Mw 6.5 October 30th mainshock. As a unique documented case reported in Italy, complex surface faulting occurred during both earthquakes along the Mt. Vettore fault. Multiple surface faulting was accompanied at depth by the development of a km-scale normal fault-propagation fold. This fold was characterized by breakthrough and by surface rupture within thick carbonatic layers only in the central and north-western area (Mt. Vettore). On the contrary, the fault remained blind where flexural slip was active in sandy-silty turbiditic deposits in the south-eastern area (Mt. Gorzano). We explain the different faulting behaviour with the occurrence of more rigid and competent lithologies in areas characterized by breakthrough and with the occurrence of weak lithologies in areas characterized by blind faulting. Overall, the entire seismic sequence appears as a gradual gravitational adjustment of the hangingwall block, slipping along a NW-trending and 80 km long fault system. In particular, the following crustal blocks, partially overlapping and with different length (30, 40 and 22 km, respectively), progressively collapsed during the sequence: the Amatrice sector during the August 24th 2016, Mw 6.0 event, the Norcia-Visso sector during the October 26th 2016, Mw 5.9 and the 2016 October 30th Mw 6.5 event, and the Campotosto Lake sector during the four January 18th 2017, M > 5 events. The progressive involvement of these three rock volumes, during the seismic sequence is here explained by the occurrence of a low angle detachment that limited the maximum potential depth of the mainshocks and consequently the dimensions of involved rock volumes, therefore limiting the magnitudes of the mainshocks.

中文翻译：

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2016-2017年Amatrice-Norcia地震序列多次地表破裂的岩性控制

摘要 2016 年 8 月 24 日，一场 Mw 6.0 地震引发了 Amatrice - Norcia（意大利中部）地震序列，该地震序列由亚平宁山脉沿线的伸展构造产生，其顶点与 10 月 30 日 Mw 6.5 的主震有关。作为意大利报道的一个独特的记录案例，在沿山的两次地震中都发生了复杂的地表断层。维托雷故障。多地表断层在深处伴随着千米级正断层传播褶皱的发展。该褶皱的特征是仅在中部和西北部（Mt. Vettore）厚碳酸盐层内发生突破和表面破裂。相反，在东南地区（Mt. Gorzano）的砂质-粉砂质浊积沉积物中弯曲滑动活跃的断层仍然是盲的。我们解释了不同的断层行为，在以突破为特征的地区出现了更刚性和更有能力的岩性，在以盲断层为特征的地区出现了弱岩性。总体而言，整个地震序列表现为上盘块的逐渐重力调整，沿着 NW 向和 80 公里长的断层系统滑动。特别是，以下地壳块体部分重叠且长度不同（分别为 30、40 和 22 公里）在序列期间逐渐坍塌：2016 年 8 月 24 日的 Amatrice 扇区，Mw 6.0 事件，Norcia-Visso 扇区2016 年 10 月 26 日，Mw 5.9 和 2016 年 10 月 30 日 Mw 6.5 事件，以及 2017 年 1 月 18 日四次的 Campotosto 湖区，M > 5 事件。