国际地震和火山电磁方法组织2016年兰州研讨会——纪念兰州地震研究所开创地电监测预报地震半个多世纪——纪念兰州地震研究所开创地电监测预报地震半个多世纪

为纪念中国地震局原兰州地震研究所开创我国地电学方法地震监测预报工作历经半个多世纪,文章在介绍国际地震和火山电磁方法组织(EMSEV)的同时,介绍了2016年8月25—29日在中国大陆首次召开、由兰州地震研究所(甘肃省地震局)为主举办单位的EMSEV国际研讨会及相关的科学活动以及会后几年来我国地震电磁学的进展。     

地电场短临预报方法研究

根据1968年注意到震前电场变化与地下水位变化及断层活动有关的理论研究, 认为震前电场变化可能是过滤电势机制引起的。 鉴于地下流体压力分布不均匀、 断层阀作用及地下电流密度与流体流的耦合方程, 特别是由于电场异常显示出快急始慢衰减的特殊图型, 电场异常有的与废油井间歇自喷有关, 有的与流体压力增高有关, 故认为过滤电势作为电场前兆机制是合理的。 实验表明铅板电极可以用来记录电场前兆。 唐山和海城特大地震时和震前, 电场水平分量或垂直分量出现同震效应或震前异常。 利用地电场的异常变化预测地震在国内外均有成功的震例, 地电场法测量技术较为简便, 可做为地震短临预报的一种手段。     

A geoelectric model for the area of the Tolbachik eruption (named after the 50 year anniverary of the Institute of Volcanology and Seismology)

We consider the methods and results of magnetotelluric sounding in the AMTS and MTS modifications. Audiomagnetotelluric sounding (AMTS) was carried out for the first time in the area of a recent Tolbachik eruption. The results from our analysis of the magnetotelluric parameters show that the geoelectric medium involving a regional fault can be fitted by a 2D inhomogeneous model. The longitudinal and transverse sounding curves were assumed as the leading elements for interpretation. A joint analysis of these curves and of pseudo-sections of impedance phases provides evidence of a geoelectric inhomogeneity in the area where the Naboko Vent is situated. A bimodal inversion of the AMTS curves yielded a geoelectric section that contains a conductive inhomogeneity that is possibly related to a fault that carried fluids up to the ground surface. Along with AMTS, we used MTS curves in a broader range to identify a crustal conductive anomaly at depths of 15–35 km. The data from AMTS, MTS, and other geological and geophysical information were used to develop a conceptual model for the area of study that characterizes a possible origin of the anomalous zones. We obtained approximate estimates of rock porosity in the fault zone that transported magma melts upward into the overlying rocks in the area of the Naboko Vent.     

地球物理研究所中短期地震预测的回顾

198 6年以来 ,地球物理研究所地震预报推进组主要承担首都圈地区月震情跟踪监测预报、年中和年度华北地区和全国地震趋势分析研究工作。本文总结了我所在填写短临预测卡片、月会商和年度会商分 3个方面所做的预测结果 ,并进行预测效能的初步评估 ,以供参考和进一步的分析和检验。1　地球物理研究所填写短临地震预测卡片的预测回顾我所自开展地震预测预报研究以来 ,一直对短临地震填卡预测采取了十分谨慎的态度 ,从 1 986年到 1 997年基本没有填写短临地震预测卡片。 1 998年以后 ,根据中国地震局预测预防司有关鼓励短临预测的规定 ,开始试验…     

Groundwater monitoring for earthquake prediction by an amateur network in Japan

Since 1976 groundwater-levels and the temperature of thermal water have been monitored in 100 wells distributed mostly in the southern Kanto and Tokai districts of Japan in order to predict earthquakes. Good examples of groundwater precursors were recognized prior to the following destructive earthquakes: the 1978 West Off Izu-Oshima Earthquake (M 7.0), the 1978 Off Miyagi Earthquakes (M 7.4), and the 1980 East Off Izu Peninsula Earthquake (M 6.7). In the 1978 West Off Izu-Oshima Earthquake, groundwater levels and the Japan Meteorological Agency (JMA) volume strainmeters, installed in the Izu peninsula, showed precursory changes at about the same time. In the other cases, however, precursory behavior was observed only in water level and temperature monitoring. Empirical relations are given between earthquake magnitude and the epicentral distance of the farthest groundwater anomaly, and between earthquake magnitude and the precursor time of groundwater.     

Character of geoelectric intermediate term precursory anomaly and judgment for intermediate term tendency of strong earthquake

IntroductionEarthquakemonitoringandpredictionisstillatthestageofexplorationandempiricalprediction.Thebasisistheanomalyvariationconsistingofseismometryindexandtheobservedresultsusingtheprecursoryapproaches.Althoughthesevariationshowsvarietyandcomplexityanditsrelationwithearthquakesisnotcertain,throughcarefullystudyingonMs>7earthquakeswecanfindthattheanomalyvariationbeforeearthquakestillshowssteadyreappearanceandhasregularity.Theyareallrelativetotheseismogenicprocess.Inthispaperwefocusonstronge…     

地震活动期、幕最大地震M1的估计及中-长期地震趋势预测

提出一种地震活动期、幕最大地震M1的估计方法：利用中低震级累计频度∑N与震级近似的直线关系得到间隔地震频度N与震级的线性关系。用间隔度N与震级的线性关系估计最大地震M1。结果表明，以震级－间隔频率的线性关系估计的M1比震级－累计频度关系得到的M1更接近实际发生的最大地震震级，震级－累计频率关系得到M1通常被高估。基于震级－累计频度关系曲线的特征和震级－间隔频度的线性关系估计的最大地震M1，可为中－长期地震趋势预测提供新的信息。研究表明，中国大陆自1979年开始的地震幕即将结束，而帕米尔东北侧自1915年以来的地震平静期也将结束。     

Characteristics of landslides in forests and grasslands triggered by the 2016 Kumamoto earthquake

We examined the characteristics of landslides triggered by the 2016 Kumamoto earthquake (Mw = 7.0: focal depth=10.0 km) in forests and grasslands within two affected watersheds (Tokosegawa: 6.9 km² and Nigorigawa: 6.1 km²) in southwestern Japan. We identified 190 landslides using aerial photographs and analyzed their sizes by geographic information system (GIS). Field investigations were conducted to obtain landslide depth, volume and residual sediment for 38 selected landslides (21 in forests and 17 in grasslands). The minimum area of detected landslides in grasslands (400 m²) was smaller than in forests (1000 m²), probably because of reduced detectability of landslides under tree cover. The ratio of total area occupied by landslides for a given range of slope gradient in the watersheds increased from 3.2% on gentle grassland slopes (10–15°) to 15.5% on steep (>45°) slopes, whereas the maximum landslide-area ratio in forest sites (7.4%) occurred on relatively gentle slopes (25–30°). Estimated landslide volume ranged from 27 to 9622 m³, based on mean depth of each landslide measured around individual landslide scars. Moreover, the volumetric ratio of landslide deposit volume to total landslide volume exceeded 100% for 48% of the landslides within forests and 35% of the landslides within grasslands. Our findings show that land cover had extensive and recognizable effects on the characteristics of landslides and resulting in-channel sediment accumulations. Resetting sediment dynamics after earthquakes associated with different land cover distributions needs to be considered within watersheds. © 2019 John Wiley & Sons, Ltd.     

文县地电场震前异常变化及其在2001年昆仑山口西M_S 8.1地震预测研究中的应用

在文县地电场观测系统中实现了地震异常信号与干扰信号的分离技术.长年的观测实践证明,文县地电场观测点是一个很灵敏的"地震窗口".研究表明,对于文县地电场观测点而言,震级、震中距、异常电信号幅度之间存在着线性关系;对带宽为0.003-30 Hz的异常信号而言,震前异常的时间长短与异常开始至发震时刻的时间长短存在着密切关系,且与震中方位有关.这些关系为文县观测点预测未来地震时、空、强"三要素"提供了很有意义的经验公式,在给出昆仑山口西M_S8.1地震预测意见中起到了良好的作用.