Precise and accurate location of the 1999 Haicheng-Xiuyan earthquake sequence
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摘要: 1999年11月29日，北京时间12点10分39秒 (04:10:39 UTC) 在我国辽宁海城——岫岩地区发生了一次MS5.4地震．这次地震是继1975年2月4日海城MS7.3地震之后该地区发生的震级最大的一次地震．区域性的辽宁数字地震台网记录了这一序列的前震、主震与余震．本文运用该台网的记录资料，用双差法对海城——岫岩地震序列重新定位，得到了该序列事件之间精确的相对位置；然后以中国地震局地球物理研究所（IGCEA）与美国南卫理大学（SMU）合作的辽宁海城——岫岩地区地震试验场宽频带地震台网（BSN）记录的、经过精准定位的地震作为近震源观测的ldquo;地面实况rdquo;（ground truth， GT）事件进行校正，得到了这一地震序列的既精确又准确的震源参数．由此得出1999年海城——岫岩地震的发震构造是与1975年海城地震的发震构造海城河——大洋河断裂邻近的康家岭断裂．康家岭断裂的走向与海城河——大洋河断裂走向一致，均为WNW-ESE方向．它们都是在中国东北——华北地区近ENE-WSW向、几乎水平的压应力场作用下产生的断裂．1999年海城——岫岩地震是在海城河——大洋河断裂的影响带动下，邻近的、与其走向一致的康家岭断裂活动的结果．Abstract: An earthquake of MS5.4 occurred in Haicheng-Xiuyan area, Liaoning, northeastern China at 12:10:39 BJT (04:10:39 UTC) on November 29, 1999. This event is the largest to occur since the 1975 Haicheng MS7.3 earthquake in Haicheng-Xiuyan area. The foreshocks, mainshock and aftershocks of the sequence were well-recorded by Liaoning Digital Seismic Network (LNDSN). Firstly, we used the regional distance travel time data recorded by the LNDSN to relocate the Haicheng-Xiuyan earthquake sequence by using double-difference earthquake location algorithm. Secondly, the earthquakes with well-recorded near-source recordings by Institute of Geophysics, China Earthquake Administration (IGCEA) and Southern Methodist University (SMU) Broadband Seismic Network (BSN) in the Haicheng-Xiuyan area are employed as ground truth (GT) events to calibrate the source parameters of the Haicheng-Xiuyan earthquake sequence. The obtained precise and accurate hypocentral distribution of the sequence clearly indicated that a nearby local Kangjialing fault is the seismogenic fault of the Haicheng-Xiuyan earthquake sequence. The WNW-ESE striking Kangjialing fault is nearly parallel to the Haichenghe-Dayanghe fault. Both the 1975 Haicheng earthquake and the 1999 Haicheng-Xiuyan earthquake are the consequence under near horizontal, ENE-WSW compression, and the occurrence of the Haicheng-Xiuyan earthquake is the activities of a nearby Kangjialing fault under of influence the Haichenghe-Dayanghe fault.
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