新西兰2016年凯库拉M_W 7.8地震灾害考察与启示

Investigation and Implication of the Seismic Disasters Caused by the 2016 Kaikoura M_W 7.8 Earthquake, New Zealand

在2016年新西兰凯库拉M_W 7.8地震中,北东—北东东向科科仁古断裂水平右旋位移量最大,为10—12m;北北西—近南北向帕帕提断裂垂直位移量最大,达到5—6m。对直接坐落在这2条地震地表破裂带或变形带之上的建筑物的破坏现场调查表明,尽管房屋出现歪斜,但上部主体部分基本完整,没有出现倒塌或部分倒塌现象,避免了人员伤亡。在无法回避活动断裂及其大震危险性的情况下,隔震系统的广泛采用可以有效地提高建筑物抵御地震灾害的能力。此次地震触发了数万个滑坡体,最大滑坡体可达数百万立方米。对沃罗村北边2处边坡失稳地带的考察结果表明,针对该地至少从2个方面进行了考虑和处置:一是在选址上,避开了突出山嘴等高陡坡地带;二是在房屋正对的山坡地带,种植或保护了茂密的树木,这既增加了山体的稳定性,又可以在地震中有效地减缓崩塌的石块对房屋的冲击。对比中国中东部一些大震,如1976年唐山7.8级地震和2008年汶川8.0级地震中触目惊心的巨大人员伤亡和财产损失,即使在人口密度与滑坡规模上存在明显不同,对新西兰凯库拉地震灾害现场的考察结果,还是在如何有效抵御地震灾害方面给我们提供了很好的启示。

The 2016 Kaikoura Mw 7.8 earthquake in New Zealand occurred at the Kekerengu fault with the strike of N-NNE and generated the horizontal displacement of 10-12m. Whereas the largest vertical displacement up to 5-6m was observed on the Papatea fault trending NNW-SN. In the field two houses are directly on these two faults. Although the houses are skewed by the ruptures along faults, the structures of the houses is basically intact, and no collapse or partial collapse was found. Such achievement of the goal of ＂Not collapse during the strong earthquake＂ successfully avoid the casualties. Generally, since the active faults and large earthquakes cannot be avoided in practice, the widespread adoption of earthquake isolation systems can effectively improve the ability of buildings to withstand earthquake disasters. The 2016 Kaikoura Mw 7.8 earthquake triggered a large number of landslides, and many landslides are with huge volumes. Although the earthquake-triggered landslides caused serious damage to traffic, there were no reports of casualties or house damage caused by landslides. Investigation of two houses on the slope region at the north of the Oaro village showed that it is not a coincidence for the ＂good luck＂ of houses and their residents during the earthquake, but is closely related to the purposive prevention in advance. In the construction of the two ＂lucky＂ houses, some aspects have been considered to increase the anti-earthquake capability. For example, the site has been selected carefully to avoid the high steep slope, and trees have been planted on the slopes to increase the stability of slope and to reduce the impact of avalanches and fall stones on the houses effectively during the earthquake. In contrast, the landslides induced by the 2008 Wenchuan earthquake have caused heavy casualties and property losses in Sichan province of China. Considering the strong earthquakes in the east of China, such as the 1976 Ms 7.8 Tangshan earthquake and the 2008 Ms 8.0 Wenchuan earthquake, there is a complex corresponding relationship between the surface ruptures induced by these earthquakes and the distribution pattern of known active faults. Finally, the population density and landslide size in China is greater than that in New Zealand, some important implications from the investigation results of the 2016 Kaikoura Mw 7.8 earthquake are very valuable for the earthquake prevention and disaster reduction planning in China.