On April 3, 2017, an earthquake of magnitude Mw 6.5 ruptured in Botswana in a region where there was no significant recent tectonic activity and where present-day deformation is believed to be negligible. The event was followed by several aftershocks distributed along NW-SE direction with NE-SW extension direction. We focused on the determination of reliable source parameters for the Mw 6.5 main shock using moment tensor inversion, in both time and frequency domains from regional, broadband waveform data. We retrieve the source depth at 38.4 km, probably the deepest earthquake observed in continental Africa. The estimated hypocentral depth of this earthquake is roughly about the Moho depth beneath the region, reflecting a deep source that is relatively rare in stable continental regions. The result may suggest that the seismogenic depth is as deep as the average global Moho thickness indicating the upper mantle and lower crust region is actively deforming due to a reactivation of the preexisting fault oriented in the NW-SE direction. The resulting focal mechanism of the event shows normal faulting with NE-SW extension direction. The result may provide useful information for contemporary geodynamic investigation of the area.

2017年4月3日，博茨瓦纳发生了6.5级Mw地震，该区域近期没有明显的构造活动，而今天的变形可以忽略不计。事件发生后，沿着NW-SE方向和NE-SW延伸方向分布了数次余震。我们专注于使用矩张量反演在时域和频域中从区域宽带波形数据中确定Mw 6.5主震的可靠震源参数。我们检索了38.4 km的震源深度，这可能是非洲大陆观察到的最深地震。估计的这次地震的震中深度大约是该区域下方的莫霍面深度，反映出在稳定的大陆地区这种罕见的深部震源。结果可能表明，地震发生深度与平均全球莫霍面厚度一样深，表明上地幔和下地壳区域由于沿NW-SE方向定向的先前断层的重新活化而正在活跃地变形。事件的最终焦点机制显示NE-SW延伸方向的正常故障。该结果可为该地区的当代地球动力学研究提供有用的信息。