基于原地应力实测数据探讨华北典型强震区断裂活动危险性及其对雄安新区的影响

华北地区距雄安新区300 km范围内包括唐山、邢台和张北三个典型强震区，近50年来，先后发生1966年邢台7.2级、1976年唐山7.8级和1998年张北6.2级强震活动，未来仍具发生破坏性地震的风险。在现今构造应力环境下，3个典型强震区内断裂活动危险性如何、再次发生中强地震对雄安新区地面稳定性有怎样的影响，这些都是要回答的问题。对此，本文首先基于唐山、邢台和张北强震区关键构造部位深孔水压致裂地应力测量数据，依据Byerlee断层滑动失稳摩擦准则，计算各强震区内潜在发震断层的临界失稳状态，探讨断裂活动危险性；之后依据中华人民共和国第五代《中国地震动参数区划图》之《中国大陆及邻区潜在震源区划分图》，厘定雄安新区外围300 km范围内主要潜在震源区和震级上限；最后选取适宜的地震烈度衰减模型，定量计算主要潜在震源区未来发生震级上限地震时对雄安新区地震烈度的影响，进而为雄安新区及重大工程抗震设防提供科学参考。结果表明：(1)唐山、邢台和张北强震区内主要潜在震源区未来发生震级上限地震产生的地震烈度衰减至雄安新区时均位于Ⅳ~Ⅶ度；(2)北京通州及邻区发生8.0级地震、涞水—高碑店沿线发生6.5级地震会在雄安新区产生Ⅶ度地震烈度，震害较轻；(3)其他潜在震源区在雄安新区产生的地震烈度均小于V度，并不会产生显著震害效应。鉴于此，雄安新区抗震设防烈度建议由原Ⅶ度调至Ⅷ度为宜。

Study of fault activity risk in typical strong seismic regions in northern China by in-situ stress measurements and the influence on the Xiongan New Area

Three typical strong seismic regions, Tangshan, Xingtai and Zhangbei, are located within 300 km radius around the Xiong'an New Area in northern China. The Xingtai M 7.2 earthquake in 1966, Tangshan M 7.8 earthquake in 1976, and Zhangbei M 6.2 earthquake in 1998 had occurred in the past 50 years and future risks of earthquake destruction in the region still exist. Under the present tectonic stress environment, what are the fault activity hazards in these three regions and how do moderate-strong earthquakes affect ground stability of the Xiong'an New Area? To answer these questions, we first calculated the critical failure state of the main potential seismogenic faults based on the hydraulic fracturing in-situ stress measurements in deep wells in the three areas, using Byerlee's fault slip friction criterion, and then investigated the fault activity hazards. Next, we determined the potential main earthquake source regions within 300 km radius of the Xiong'an New Area and the maximum earthquake magnitude for each source region, according to the fifth generation seismic ground motion parameters zonation map as well as potential source regions zonation map of China. Finally, we used the appropriate seismic intensity attenuation model to quantitatively calculate the seismic intensity attenuation in the Xiong'an New Area from the three strong seismic areas, providing some scientific guidelines for seismic fortification of major projects in the Xiong'an New Area. The results show that (1) if potential maximum magnitude earthquakes occur in the three strong earthquake regions, the attenuation of seismic intensity in the Xiong'an New Area will vary between Ⅳ and Ⅶ degrees; (2) the potential M 8.0 earthquake in the Tongzhou district of Beijing, or M 6.5 earthquake along the Laishui-Gaobeidian of Baoding, will generate Ⅶ degrees of intensity attenuation in the Xiong'an New Area, which may result in minor earthquake damage; (3) the attenuation of seismic intensity produced by other potential seismic source areas will be less than V degrees, causing no significant seismic damage in the Xiong'an New Area. Therefore, the seismic fortification intensity of the Xiong'an New Area is recommended to be adjusted from the original Ⅶ degrees to Ⅷ degrees.