On 3 May 2020, an M_L 3.1 earthquake occurred in Haenam, southwestern Korea, in an area devoid of recorded seismicity since instrumental observations began in 1978. Careful examination of the temporal occurrence of seismicity, and the magnitude distribution of the sequence before and after the M_L 3.1 earthquake, indicates typical swarm-like behavior. The earthquake swarm started with an M_L 0.6 event on 26 April 2020, intensified up to 3 May 2020, and abruptly terminated with an M_L 1.0 event on 9 May 2020. The Pusan National University Geophysics Laboratory (PNUGL) deployed a temporary seismic array with eight three-component short-period instruments to monitor the short-lived bursts of seismicity. During the monitoring campaign, we detected > 700 microearthquakes by applying a matched-filter technique to the combined dataset produced by PNUGL, the Korea Meteorological Administration, and the Korea Institute of Ocean Science and Technology. We determined earthquake parameters for 299 earthquakes that were detected at four or more seismic stations. We also determined the focal mechanism solutions of the 10 largest earthquakes in the swarm using first-motion polarities with S/P ratios. The focal mechanism, hypocentral depth, and stress orientation of the largest earthquake in the sequence were also determined using waveform inversions. The distribution of earthquake hypocenters, together with focal mechanism solutions, indicates that the earthquake swarm activated deeply-buried faults (~20 km) oriented either NNE-SSW or WNW-ESE. We also report details of the temporary seismic monitoring network, including the instrumentation, detection of microearthquakes, and variations in event-detection threshold influenced by anthropogenic and natural noise fluctuations. We also discuss the limitations associated with lowering the detection threshold of microearthquakes by increasing the number of seismic stations or by adopting advanced event-detection techniques.

自1978年开始进行仪器观测以来，2020年5月3日，韩国西南海南发生了M _L 3.1地震，该区域没有地震记录。仔细检查地震的时间性发生以及前后地震序列的大小分布在中号_大号3.1级地震，表明典型群的行为。地震群始于2020年4月26日的M _L 0.6事件，加剧至2020年5月3日，并突然终止为M _L2020年5月9日的1.0级事件。釜山大学地球物理实验室（PNUGL）部署了一个临时地震阵列，其中包含8个三分量短周期仪器，以监测短期的地震爆发。在监视活动中，我们通过对PNUGL，韩国气象局和韩国海洋科学技术学院生成的组合数据集应用匹配过滤器技术，检测到700多个微地震。我们确定了在四个或更多地震台站检测到的299次地震的地震参数。我们还使用具有S / P比的第一运动极性确定了该群体中10大地震的震源机制解。震源机制，震中深度 还使用波形反演确定了该序列中最大地震的应力方向。地震震源的分布以及震源机制解表明，地震群激活了以NNE-SSW或WNW-ESE为主的深埋断层（约20 km）。我们还报告了临时地震监测网络的详细信息，包括仪器，微地震的检测以及受人为和自然噪声波动影响的事件检测阈值的变化。我们还将讨论通过增加地震台数或采用先进的事件检测技术来降低微地震的检测阈值的局限性。表明地震群激活了以NNE-SSW或WNW-ESE为主的深层断层（约20 km）。我们还报告了临时地震监测网络的详细信息，包括仪器，微地震的检测以及受人为和自然噪声波动影响的事件检测阈值的变化。我们还将讨论通过增加地震台数或采用先进的事件检测技术来降低微地震的检测阈值的局限性。表明地震群激活了以NNE-SSW或WNW-ESE为主的深层断层（约20 km）。我们还报告了临时地震监测网络的详细信息，包括仪器，微地震的检测以及受人为和自然噪声波动影响的事件检测阈值的变化。我们还将讨论通过增加地震台数或采用先进的事件检测技术来降低微地震的检测阈值的局限性。以及人为和自然噪声波动影响的事件检测阈值的变化。我们还将讨论通过增加地震台数或采用先进的事件检测技术来降低微地震的检测阈值的局限性。以及人为和自然噪声波动影响的事件检测阈值的变化。我们还将讨论通过增加地震台数或采用先进的事件检测技术来降低微地震的检测阈值的局限性。