Abstract The Oran region (Western Tell Atlas) was hit by two earthquakes on January 9th, 2008 (Mw = 4.7) and on June 6th, 2008 (Mw = 5.4). The two events were recorded by the national accelerographs network maintained by National Center of Applied Research in Earthquakes Engineering (CGS, Algiers). This work aims to characterize these two earthquakes in order to contribute to understand the seismotectonic context of the study region. We located the events using Grid Search Method based on P and S waves arrival time differences. The obtained hypocenter locations are, respectively, (0.457°W, 35.689°N, 11 km) and (0.576°W, 35.689°N, 8 km). We perform waveforms inversion to estimate the moment magnitude s and the seismic moments which are, respectively, Mw = 4.7, M0 = 0.13 E+17 N m and Mw = 5.4, M0 = 0.18 10 E+18 N m for the two events. Concerning the focal mechanism solutions both earthquakes yield reverse faulting with a compressional axes oriented NW-SE which is consistent with the active fault system trend in the study region. These two events occurred in an area which has been seismically quiet, since the event of December 1959 (Ms 4.7) and the historical major event of October 9th, 1790 (I0= IX-X; likely Ms ≥ 6.0).

中文翻译：

---

奥兰 1 月 9 日（Mw 4.7）和 2008 年 6 月 6 日（Mw 5.4）地震：地震学研究和地震构造意义

摘要 2008 年 1 月 9 日（Mw = 4.7）和 2008 年 6 月 6 日（Mw = 5.4），奥兰地区（Western Tell Atlas）发生了两次地震。这两个事件由国家地震工程应用研究中心（CGS，阿尔及尔）维护的国家加速度计网络记录。这项工作旨在描述这两次地震的特征，以有助于了解研究区域的地震构造背景。我们使用基于 P 波和 S 波到达时间差异的网格搜索方法定位事件。获得的震源位置分别为 (0.457°W, 35.689°N, 11 km) 和 (0.576°W, 35.689°N, 8 km)。我们执行波形反演以估计两个事件的矩震级 s 和地震矩，它们分别为 Mw = 4.7、M0 = 0.13 E+17 N m 和 Mw = 5.4、M0 = 0.18 10 E+18 N m。关于震源机制的解决方案，两次地震都产生了压缩轴朝向 NW-SE 的反向断层，这与研究区的活动断层系统趋势一致。这两个事件发生在自 1959 年 12 月的事件（Ms 4.7）和 1790 年 10 月 9 日的历史性重大事件（I0= IX-X；可能 Ms ≥ 6.0）以来地震平静的地区。