The Querétaro region (central Mexico) is located in the trans‐Mexican volcanic belt, an active volcanic arc related to the subduction of oceanic plates along the Pacific margin of Mexico. It is characterized by north–south‐striking normal faults of the southern Basin and Range Province, up to 40 km long and with morphologically pronounced scarps, such as the San Miguel de Allende fault and the faults forming the Querétaro graben. These faults are located directly north of a major regional‐scale system of east–west striking, seismically active intra‐arc normal faults that are oriented parallel to the axis of the volcanic arc. Where the two orthogonal normal fault systems interfere, the outcrop‐scale observations show that the east–west intra‐arc fault system overprints the Basin and Range Province structures. Here we document a 1934 earthquake in a region previously not known for seismic activity. Our study is mostly based on an unpublished contemporary dossier preserved at Archivo Histórico del Instituto de Geología de la Universidad Nacional Autónoma de México, a recently inventoried archive that also preserves several unpublished macroseismic and instrumental studies of major Mexican subduction zone earthquakes between 1911 and 1954. A mainshock–aftershock sequence that initiated 14 July 1934 is documented by instrumental recordings at the Tacubaya observatory and by macroseismic observations at ten population centers, ranging in intensity between five and seven on the modified Mercalli scale. Based on the size of the damage area, the intensity magnitude of the mainshock is estimated at 4.8 ± 0.5. Based on the intensity distribution, the epicenter was located in the Laja River valley north‐northeast of the town of Celaya, in the south‐southwestern extrapolated continuation of the San Miguel de Allende normal fault scarp, which suggests that this fault extends to the epicentral region of the 1934 earthquake and is characterized by recurrent Quaternary tectonic activity.

中文翻译：

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克雷塔罗地区（墨西哥中部）的地震构造和 1934 年塞拉亚北部 MI 4.8 地震

克雷塔罗地区（墨西哥中部）位于跨墨西哥火山带，这是一条与墨西哥太平洋边缘海洋板块俯冲有关的活跃火山弧。它的特点是南部盆地省的南北向正断层，长达40公里，陡坡形态明显，例如圣米格尔德阿连德断层和形成克雷塔罗地堑的断层。这些断层位于主要区域规模系统的正北，该系统由东西走向、地震活跃的弧内正断层组成，其方向平行于火山弧轴。在两个正交正断层系统干涉的地方，露头规模的观测表明，东西向的弧内断层系统覆盖了盆岭省的构造。在这里，我们记录了 1934 年发生在一个以前不知道地震活动的地区的地震。我们的研究主要基于墨西哥国立自治大学地质研究所保存的未发表的当代档案，该档案是最近清点的档案，还保存了几项未发表的关于 1911 年至 1954 年间墨西哥俯冲带主要地震的宏观地震和仪器研究。塔库巴亚天文台的仪器记录和 10 个人口中心的宏观地震观测记录了 1934 年 7 月 14 日开始的主震-余震序列，根据修改后的麦卡利震级，震级在 5 到 7 级之间。根据受损区域的大小，估计主震震级为4.8±0.5级。根据强度分布，震中位于塞拉亚镇东北偏北的拉哈河谷，位于圣米格尔德阿连德正断层陡坎的南西南延伸部分，这表明该断层延伸至震中该地区是 1934 年地震的地区，以经常发生的第四纪构造活动为特征。