华南地震

2019年10月12日广西北流—广东化州5.2级地震特征分析

邓志辉¹^,²,刘吉平¹^,²,吕金水¹,叶东华¹,廖桂金¹,王小娜¹^,²,刘锦¹,刘特培¹,李健梅¹

（1.广东省地震局,广州 510070；2.南方海洋科学与工程广东省实验室,广东珠海 519000）

关键词：广西北流—广东化州地震;博白—茂名断裂;地震活动;流动重力;地下流体;井孔应变

Characteristics of Huazhou-Beiliu M_S5.2 Earthquake on October 12^th, 2019

DENG Zhihui¹^,²,LIU Jiping¹^,²,LYU Jinshui¹,YE Donghua¹,LIAO Guijin¹,WANG Xiaona¹^,², LIU Jin¹, LIU Tepei¹,LI Jianmei¹

（1.Guangdong Earthquake Agency, Guangzhou 510070,China;2.Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519000, China）

Keywords：Huazhou-Beiliu earthquake;Bobai-Maoming fault; Seismic activity;Flowing gravity;Underground fluid; Borehole strain

DOI: 10.13512/j.hndz.2020.02.01

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参考文献

2019年10月12日,在广东省化州市与广西壮族自治区北流市交界地区发生5.2级地震,这是华南地区进入20世纪以来第Ⅴ活跃幕之后发生的第3次5级以上地震,也是粤桂交界地区第Ⅴ活跃幕以来第2次5级以上地震。此地震发生北西向巴马—博白—茂名断裂带的陆川—高州段上,属6级潜在震源区,基本烈度为Ⅵ度区。震中区在历史上属于少震弱震区,但从2014年以来,地震活动出现间歇性增强,多项地球物理观测数据也时有异常表现。广东省地震局在2018年度地震会商时把此区域确定为2019年度地震危险重点注意地区。10月12日5.2级地震的发生验证了年度地震危险重点注意地区的判定,为以后的地震预测工作提供了可参考的分析依据。

On October 12th,2019, an MS5.2 earthquake occurred at the junction of Huazhou City,Guangdong Province and Beiliu City,Guangxi Zhuang Autonomous Region,which is the third earthquake with MS≥5 after the South China region entered the second active period and the fifth active scene,and is also the second earthquake with MS≥5 since the fifth active scene in the border area between Guangdong and Guangxi.This earthquake occurred on the Luchuan-Gaozhou section of the Bama-Bobai-Maoming fault zone in the northwest direction, which is a potential source of magnitude 6 with a basic intensity of Ⅵ.The epicentral area is a weak earthquake areahistorically,but since 2014,seismic activity has increased intermittently,and many geophysical observations also have anomalous performance. The Guangdong earthquake agency identified the area as a keyearthquake hazard area in 2019in the annual earthquake conference(2018).The occurrence of the MS5.2 earthquake has verified the judgment of the key earthquake hazard areaof the year and provided a reference for the future earthquake prediction.

引言
1 地震概况
2 发震构造特征
3 地震活动特征
4 地震预测实践
5 结语

图1 化州—北流及其附近地区地震构造图<br/>Fig.1 Earthquake tectonic map of Huazhou-Beiliu and its vicinity

图1 化州—北流及其附近地区地震构造图
Fig.1 Earthquake tectonic map of Huazhou-Beiliu and its vicinity

表1 震中附近历史地震记录（MS≥5.0）<br/>Table 1 Historical earthquake records near the epicenter (MS≥5.0)M

表1 震中附近历史地震记录（MS≥5.0）
Table 1 Historical earthquake records near the epicenter (MS≥5.0)M

图2 历史地震M-t图（MS≥5.0）<br/>Fig.2 M-t map of historical earthquakes (MS≥5.0)

图2 历史地震M-t图（MS≥5.0）
Fig.2 M-t map of historical earthquakes (MS≥5.0)

图4 粤桂交界地区地震应变能的累积释放和G-R关系曲线（1850—2018）<br/>Fig.4 Accumulative release of seismic strain energy and G-R relationship curve in the border area between Guangdong and Guangxi (1850—2018)

图4 粤桂交界地区地震应变能的累积释放和G-R关系曲线（1850—2018）
Fig.4 Accumulative release of seismic strain energy and G-R relationship curve in the border area between Guangdong and Guangxi (1850—2018)

图5 震中附近50km范围内ML≥1.0级地震分布图（1970年至2019年10月11日）<br/>Fig.5 Distribution map ofearthquakes with ML≥1.0 within 50 km of the epicenter (from 1970 to October 11th,2019)

图5 震中附近50km范围内ML≥1.0级地震分布图（1970年至2019年10月11日）
Fig.5 Distribution map ofearthquakes with ML≥1.0 within 50 km of the epicenter (from 1970 to October 11th,2019)

图6 震中附近50 km 范围内1970年以来ML≥1.0级地震M-T图<br/>Fig.6 M-T map of earthquakes with ML≥1.0 within 50 km of the epicenter since 1970

图6 震中附近50 km 范围内1970年以来ML≥1.0级地震M-T图
Fig.6 M-T map of earthquakes with ML≥1.0 within 50 km of the epicenter since 1970

图7 震中附近50 km 范围内1970年以来ML≥1.0级地震频度分布图<br/>Fig.7 Frequency distribution of earthquakes with ML≥1.0within 50 km of the epicenter since 1970

图7 震中附近50 km 范围内1970年以来ML≥1.0级地震频度分布图
Fig.7 Frequency distribution of earthquakes with ML≥1.0within 50 km of the epicenter since 1970

图8 震中附近50 km 范围内2015年以来ML≥1.0级地震M-T图<br/>Fig.8 M-T map of earthquakes with ML≥1.0 within 50 km of the epicenter since 2015

图8 震中附近50 km 范围内2015年以来ML≥1.0级地震M-T图
Fig.8 M-T map of earthquakes with ML≥1.0 within 50 km of the epicenter since 2015

图9 震中附近50 km 范围内2015年以来ML≥1.0级地震频度分布图<br/>Fig.9 Frequency distribution of earthquakes with ML≥1.0 within 50 km of the epicenter since 2015

图9 震中附近50 km 范围内2015年以来ML≥1.0级地震频度分布图
Fig.9 Frequency distribution of earthquakes with ML≥1.0 within 50 km of the epicenter since 2015

图10 区域ML≥1.0级地震活动频度变化分布图<br/>Fig.10 Distribution of seismic activity frequency changeof earthquakes with ML≥1.0 in the region

图10 区域ML≥1.0级地震活动频度变化分布图
Fig.10 Distribution of seismic activity frequency changeof earthquakes with ML≥1.0 in the region

图11 区域背景b值（1970—2017）空间分布（a）及震前Δb值变化<br/>Fig.11 Spatial distribution of regional background b value (1790—2017) (a) and distribution mapofΔb value change before earthquake(2018 b value-background value) (b)

图11 区域背景b值（1970—2017）空间分布（a）及震前Δb值变化
Fig.11 Spatial distribution of regional background b value (1790—2017) (a) and distribution mapofΔb value change before earthquake(2018 b value-background value) (b)

图12 粤桂琼交界及其邻海多地震活动参数时间扫描结果<br/>Fig.12 Time-scan results of multiple seismic activity parameters inthe border between Guangdong,Guangxi,and Hainan and its adjacent sea

图12 粤桂琼交界及其邻海多地震活动参数时间扫描结果
Fig.12 Time-scan results of multiple seismic activity parameters inthe border between Guangdong,Guangxi,and Hainan and its adjacent sea

图13 粤桂交界中南部地区地震活动图像PI计算结果（据广东省地震局,2018）<br/>Fig.13 PI calculation results of seismic activity images in the central and southern areas of the junction of Guangdong and Guangxi (according to the Guangdong Earthquake Agency,2018)

图13 粤桂交界中南部地区地震活动图像PI计算结果（据广东省地震局,2018）
Fig.13 PI calculation results of seismic activity images in the central and southern areas of the junction of Guangdong and Guangxi (according to the Guangdong Earthquake Agency,2018)

图14 粤西地区流动重力场年变化异常分布图（2018-03~2018-08）<br/>Fig.14 Anomalous distribution of the annual variation of the mobile gravity field in western Guangdong (2018.3-2018.8)

图14 粤西地区流动重力场年变化异常分布图（2018-03~2018-08）
Fig.14 Anomalous distribution of the annual variation of the mobile gravity field in western Guangdong (2018.3-2018.8)