Determination of Seismicity Parameters in Himalayan Seismic Belt
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摘要: GB 18306—2015《中国地震动参数区划图》发布距今已有十多年,期间,地震资料(尤其是青藏地震区地震资料)发生了较大变化,及时开展相关地震带地震活动性参数研究对重大建设工程抗震设防安全具有重要意义。本文研究补充了600余条地震目录,其中8.0~8.9级地震7次,7.0~7.9级地震35次,并分析了地震资料的完整性:由于历史、地理、人文的原因,喜马拉雅地震带地震遗漏较严重,7级地震直至1897年才基本完整,6级地震直至1950年才基本完整,5级地震直至1980年才基本完整;本文根据8级以上地震密集活动时段划分了地震活动周期,公元1803年以来可以划分出2个活动周期,并对未来地震活动进行了预测;采用多种方案拟合了喜马拉雅地震带的b值和4级以上地震年发生率:b=0.90,v4=162,并与前人的计算结果进行了简单对比。Abstract: It has been more than ten years since the release of GB 18306—2015 "Seismic ground motion parameters zonation map of China". During this period, great changes have taken place in the seismic data, especially in the Qinghai Tibet seismic area. Timely research on the seismicity parameters of relevant seismic zones is of great significance for the seismic fortification safety of major construction projects. This work has supplemented more than 600 earthquake catalogs, including 7 earthquakes of M8~8.9 and 35 earthquakes of M7~7.9, and the integrity of seismic data is analyzed. Due to historical, geographical and cultural reasons, the earthquake omission in the Himalayan seismic belt is serious. The M7 earthquakes were basically complete until 1897, the M6 earthquakes were basically complete until 1950, and the M5 earthquakes were basically complete until 1980. The seismicity period is divided according to the intensive activity period of earthquakes above M8. Since 1803, two activity periods can be divided, and the future seismicity is predicted. Multiple schemes are used to fit the b value of the Himalayan seismic belt and the annual occurrence rate of earthquakes with M≥ 4: b = 0.90, v4 = 162, and the results are simply compared with the previous calculation results.
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Key words:
- Himalayan seismic belt /
- Seismic activity parameters /
- b value
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表 1 喜马拉雅地震带5级以上地震频次(公元25年~2021年12月)
Table 1. Frequency of earthquakes above M5 in Himalayan seismic belt (25 AD ~ December 2021)
类别 震级/级 总数 5.0~5.9 6.0~6.9 7.0~7.9 8.0~8.6 第五代区划图地震目录(截止2008年) 348 55 9 2 412 本研究增加地震目录 2008年前 270 152 33 7 666 2009年~2021年 187 15 2 0 表 2 喜马拉雅地震带1800年以来活动周期分析
Table 2. Activity period analysis of Himalayan seismic belt since 1800
起止时间/年 7.0~7.9级 8级以上 最大震级/级 持续时间/年 周期划分 1803~1846 3 3 8.1 43 高潮期 第1活动周期 1847~1896 7 0 7.6 49 平静期 1897~1956 21 3 8.2 59 高潮期 第2活动周期 1957~2004 5 0 7.6 47 平静期 2005~2021(预计到2050年) 8 0 7.8 16 高潮期 新的活动周期 表 3 喜马拉雅地震带活动周期年平均发生率
Table 3. Annual average occurrence rate of active period in Himalayan seismic belt
时间/年 统计类别 震级/级 ≥5.0 ≥5.5 ≥6.0 ≥6.5 ≥7.0 ≥7.5 ≥8.0 ≥8.5 1897~1956 频次 325 201 103 48 24 8 3 1 年累计发生率 5.4167 3.3500 1.7167 0.8000 0.4000 0.1333 0.0500 0.0167 1897~2021 频次 1269 460 204 79 31 11 3 1 年累计发生率 10.1520 3.680 1.6320 0.6320 0.2480 0.0880 0.0240 0.008 表 4 喜马拉雅地震带 b 值及地震发生率ν值
Table 4. The b values and levels of Himalayan seismic belt ν value
时间/年 参数 b a ν4 ν5 ν7 ν7.5 ν8 ν8.5 δ 1897~1956 0.72 4.65 59 11 0.4074 0.1778 0.0776 0.0399 0.2902 1897~2021 1.04 6.66 316 28 0.2399 0.0724 0.0219 0.0066 0.8894 表 5 喜马拉雅地震带不同时段地震年平均发生率
Table 5. Annual average occurrence rate of earthquakes in different periods of Himalayan seismic belt
项目 时间/年 震级/级 ≥5.0 ≥5.5 ≥6.0 ≥6.5 ≥7.0 ≥7.5 ≥8.0 ≥8.5 年平均发生率 1897~2021 — — — — 0.2480 0.0880 0.0240 0.0080 1950~2021 — — 1.9861 0.5833 — — — — 1980~2021 13.6905 3.5238 — — — — — — 表 6 喜马拉雅地震带地震年发生率结果对比
Table 6. Comparison of annual occurrence rate results of Himalayan seismic belt
项目 统计方式 参数 b a v 4 v 5 v 7 v 7.5 v 8 v 8.5 δ 年发生率 1897~2021 1.04 6.66 316 28 0.2399 0.0724 0.0219 0.0066 0.8894 分段统计(可信震级与可信时段) 0.90 5.81 162 20 0.3236 0.1148 0.0407 0.0145 0.1964 -
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