| 2021年青海玛多Mw 7.4地震前后b值的变化特征研究 |
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| 引用本文： | 江颖,刘子维,张晓彤,张丽娜,韦进.2021年青海玛多Mw 7.4地震前后b值的变化特征研究[J].武汉大学学报(信息科学版),2022,47(6):907-915. |
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| 作者姓名： | 江颖 刘子维 张晓彤 张丽娜 韦进 |
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| 作者单位： | 1.中国地震局地震研究所，湖北 武汉，430071 |
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| 基金项目： | 国家自然科学基金41774093 |
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| 摘 要： | 古登堡-里克特频度-震级关系式中的b值常被用作估算区域应力大小的一个重要指标，对于评估地震发生概率起着至关重要的作用。北京时间2021-05-22T02:04:11青海省玛多县附近发生Mw 7.4地震，此次地震发生在巴颜喀拉块体内部，东昆仑断裂以南的次级断裂昆仑山口-江错断裂上。为了揭示这次玛多地震之前震源区的孕震环境和震后余震的演化，利用中国地震台网中心提供的2009-01-01-2021-05-20地震目录，对玛多地震发震前后的b值分布和变化进行了研究。研究发现，在2021年5月22日之前，玛多地震主震区b值最低，表明震源区存在明显的应力积累；从近十年震源区b值的时间序列来看，b值也呈现下降趋势，该发现可以作为今后判定块体内部大地震主震临近的重要依据。利用震后的余震序列计算了断层周边的b值变化，发现早期的b值变化对后期余震的发生位置预测也具有一定的指导作用。
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| 关 键 词： | 玛多地震 古登堡-里克特频度-震级关系 b值 完备震级 地震危险性 构造应力 |
| 收稿时间： | 2022-05-09 |
Variation Features of b-Value Before and After the 2021 Maduo Mw 7.4 Earthquake |
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| Affiliation: | 1.Institute of Seismology, China Earthquake Administration, Wuhan 430071, China2.Institute of Disaster Prevention, Langfang 065201, China3.National Observation and Research Station of Gravitation and Earth Tide, Wuhan 430071, China |
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| Abstract: | Objectives The b-value in the Gutenberg-Richter relation is often used as an essential indicator for estimating the magnitude of regional stress, and it plays a vital role in evaluating the probability of earthquake occurrence. At 02:04:11 on May 22th, 2021, an Mw 7.4 earthquake occurred in Maduo County, Qinghai Province. The Maduo earthquake unexpectedly occurred inside the Bayan Har block, and located in Kunlun-Jiangcuo fault, which is a secondary fault in south of the East Kunlun fault. Methods To reveal the seismogenic environment of the source region before the Maduo earthquake and the evolution of the aftershocks, the distribution and change of b-value before the Maduo earthquake are investigated by using the earthquake catalog provided by the China Earthquake Networks Center from January 1, 2009 to May 20, 2021. The catalog includes 32 230 well-located events with a complete magnitude. Results The results indicate that b-value in the source area is extremely low before the 2021 Maduo earthquake, indicating a significant stress accumulation in the source region. Moreover, there is a noticeable decrease in b-value in the source region before the 2021 event. Conclusions The b-value is an essential indicator of the upcoming great earthquake and has excellent potential for predicting a future large earthquake within the block. Moreover, the early b-value variations are of guiding significance to the location prediction of aftershock in the future. |
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