The regulations and technical systems for earthquake early warning in Japan have been continuously updated and developed in recent years. Starting from February 1, 2023, long-term earthquake motion prediction information was officially included in the Japan earthquake warning release. Since 2015, the underwater observation network has been integrated into the early warning system, effectively shortening the time for the first warning of earthquakes occurring along the coast of the Japan Trench. In 2018, the PLUM method was introduced to enable the system to make earthquake motion predictions even when traditional methods fail. At present, efforts are focused on solving the problem of frequent occurrence of excessive earthquake motion prediction. The Japan Meteorological Agency has introduced the integrated IPF method by the end of 2023 to reduce the rate of excessive earthquake motion prediction. The problems encountered in the current development of earthquake early warning technology and applications in Japan, as well as the envisioned future key development directions, provide useful references for the development of earthquake early warning in China.

The National Earthquake Hazards Reduction Program (NEHRP) is the main coordination plan for earthquake disaster reduction at the level of the Federal Government of the United States. The United States Congress has made periodic adjustments in the form of planned reauthorizations. In 1990, 1997, 2000, and 2004, adjustments were made to the focus and supervision of NEHRP through reauthorization. In fact, the 2004 reauthorization bill expired in 2009. Although the US Congress continued to provide funding annually, the reauthorization was delayed until 2018. In the 2018 adjustment, NEHRP made significant directional adjustments to highlight earthquake warning and earthquake resilience construction. In May 2023, NEHRP released the “Strategic Plan for the NEHRP Fiscal Years 2022—2029” on its website, implementing the adjustment requirements of the 2018 Reauthorization Act, sorting out and integrating existing NEHRP goals and tasks, setting four integration goals and eighteen support tasks, and determining eight key investment areas. This plan is a guiding document for the new stage of earthquake disaster reduction in the United States, and has strong reference significance for China’s earthquake prevention and disaster reduction work.

做好地震信息服务需要深入研究服务的公众触达和反馈.随着国家地震预警工程的推进,地震预警系统即将大范围面向公众提供服务,因此公众的地震预警需求、地震预警误报接受程度等问题亟需研究.本文设计了防震减灾公共服务公众接触率及公众满意度调查指标体系,用以量化测量防震减灾公共服务的公众触达现状和反馈评价,并取得了较好的效果.全国公众调查结果显示,分别有80.7％,56.2％,29.5％和26.7％的受访者接触过地震速报信息服务、防震减灾知识科普、自建房抗震咨询服务和各级地震部门门户平台,各项服务的公众接触有明显的区域和人群特征.公众反馈评价总体较好,但是地震速报信息服务及时性的满意度评价得分相对较低,显示公众对地震速报信息发布时效性在近年来取得的进步缺乏直观感受.地震预警公众需求研究结果显示,88.3％的公众认为地震预警有必要,56.8％的公众对地震预警信息有强烈需求,公众对地震预警误报的接受程度在过去十年时间里保持在一个较高水平,大城市和地震多发区公众对地震预警的需求和对地震预警误报接受程度均显著高于全国公众总体水平.

本文针对2020年全国公众防震减灾科普满意度调查工作,设计了防震减灾科普公众接触率、受众收获评价、公众满意度和需求等指标,量化衡量防震减灾科普在公众中的触达现状、公众的收获评价、反馈评价和需求.调查结果显示,公众与防震减灾科普的接触较普遍,受众收获评价和满意度评价总体得分较高.防震减灾科普公众接触率在不同城乡、年龄、学历、职业等层面的群体差异较明显.科普活动的公众接触率相对较低,受众收获评价较高,公众对活动新颖性的满意度评价低于活动组织管理.科普作品的公众接触率最高,但受众收获评价较低,在促进公众技能提升方面具有明显短板,公众对作品形式新颖性的满意度评价低于内容通俗易懂性.科普场所的公众接触率最低,但受众收获评价最高,对公众知识、技能、意识的提升作用较好.公众对科普场所信息查找便利性的满意度较低,导致科普场所满意度评价低于科普活动和科普作品.分析表明,需重视公众需求和反馈,采取有针对性的措施进一步提升防震减灾科普效率.

2020年中国地震局开展了全国公众防震减灾知识普及和科普满意度抽样调查,结果显示,17.1％的受访者具备防震减灾素养,与2018年中国公民科学素质调查结果相比较,公众防震减灾素养水平的区域分布有明显不一样的规律,公众防震减灾素养水平与区域经济发展水平之间没有明显的相关性,区域地震灾害程度和个人地震经历对公众防震减灾素养水平有显著的影响.防震减灾素养水平在城乡、性别、受教育水平等不同群体中的差别,和中国公民科学素质调查结果基本一致,受教育水平对防震减灾素养水平影响最大.在不同年龄群体中的差别则和中国公民科学素质调查结果不同,显示出独特的规律.在防震减灾科普工作中,需要重视公众防震减灾素养水平的这些特点,采取有针对性的措施来提升科普效率.

为了更好地了解防震减灾公共服务的基本现状、 分析公众的防震减灾公共服务需求,2018年与国家统计局社情民意调查中心合作,开展了全国公众防震减灾基础调查.对31个省份18～75周岁的城乡居民进行分层抽样,采用计算机辅助电话调查的方法共获得20078个有效样本.结果 表明,全国公众地震应急演练参与度仅27.4％;防震减灾知识宣传知晓度为73.5％,满意度为75.22分;公众对地震信息的关注度高达82.9％,地震信息获取便利度评价为81.51分;公众对地震部门发布信息的权威性评价为83.69分;全国防震减灾公共服务总体感受满意度评分为76.44分;震后救援和灾后重建、地震预警、房屋抗震能力测试为公众最想获取的3类防震减灾公共服务.文中获得的调查分析结果可为防震减灾公共服务评价和现代化建设提供参考.

地震是地壳中积累的大量弹性应变能突然释放的灾变破坏过程.对地震的预测(特别是短临预测)一直是地震学的一个巨大挑战,《Science》(2005)曾将其列为125 个科学问题之一(Arethere earthquake precursors that can lead to useful predictions? ).解决这一问题的关键点在于,是否存在与地震发生具有因果关联的、有物理基础的前兆现象?利用何种观测手段来探测并识别这种前兆现象?以及如何从噪声信号中将这种前兆信号分离出来?只有基于那些可测量的物理前兆,地震预测方法才能够建立起来.

Based on continuous GPS data from crustal movement observation network of China (CMONOC), the vertical deformations on Earth's surface observed by 234 GPS stations and GRACE in mainland China are compared with each other.GPS-observed and GRACE-derived vertical deformations are in good agreements in general, which indicates that mass loading is an important factor to GPS nonlinear variations, but there are some differences between GPS and GRACE.For further analyzing the difference between GPS and GRACE vertical deformations, we take into account the thermal expansion effects to GPS vertical deformations and the effect of regional crustal structure on vertical loading deformations derived from GRACE.It is found that the annual amplitudes of vertical deformations induced by thermal expansion are not less than 1 mm at more than 50% of GPS stations.After considering thermal deformations, the vertical deformations of GPS and GRACE are with higher consistency in mainland China.The ratio of annual amplitudes from GPS and GRACE vertical deformations changes from 1.07±0.06 to 1.01±0.05, which is closer to the ideal value of 1.Thermal expansion can explain 6.2% of the difference between GPS and GRACE vertical deformations.And it can increase the consistency of vertical deformations between GPS and GRACE by 11.2% relatively after thermal expansion correction.The regional crustal structure has little effect on GRARE-derived vertical loading deformations in mainland China and the relative difference is 2.5%.

On 8 August 2017 an earthquake of magnitude 7. 0 struck Jiuzhaigou, Sichuan Province. Coseismic displacements of this event have been captured by both the GNSS continuous stations of the Tectonic and Environmental Observation Network of Mainland China and the Ground Reinforcement System (coordinates: east is positive, north is positive). The results show that of three sites of the above observation have recorded obvious coseismic horizontal displacements. Of them, the SCJZ site 43 km to the epicenter observed a displacement of -9. 8 +/- 1. 5 mm in the east-west direction and 3. 3 +/- 0. 7 mm in the north-south direction, respectively. The SCSP site 65 km to the epicenter measured displacement of -1. 8 +/- 0. 7 mm in the east-west direction and -7. 7 +/- 0. 6 mm in the north-south direction, respectively. At GSZQ site, 77 km to the epicenter, displacements of 0. 4 +/- 1. 2 mm in the east-west direction and 3. 67 +/- 0. 8 mm in the north-south direction were detected. The distribution of these coseismic displacements suggests that the earthquake is a sinistral strike-slip event, causing the horizontal deformation within an extent less than 150 km with a very small effect on the Longmenshan fault zone in the southeast. The displacements on the Tazang fault and the Minjiang fault reach several centimeters. The results of inversion of the coseismic displacements/show that the slip on the fault plane is mainly concentrated around 7 km depth, with maximum about 0. 4 m and an average slip angle -15 degrees. The corresponding moment magnitude calculated by the slip distribution is about M(w)6. 4, which is equivalent to that from seismic wave inversion. Based on the characteristics of coseismic slip distribution, principal strain distribution, aftershock distribution and focal mechanism solutions, it is inferred that the energy accumulated in the extreme area of the earthquake rupture is fully released, causing a significant stress change on the Tazang fault, the Minjiang fault and the Huya fault, which should receive continual attention.

Based on more than two years BDS/GPS data observed by seven stations,we used precise point positioning (PPP) model of the PANDA software developed by Wuhan University,analyzed the positioning accuracy of single system and discussed the ability of BDS in crustal motion monitoring.The results showed that the BDS positioning accuracy in the horizontal direction was about 17 mm and the vertical direction was about 40 mm.The GPS positioning accuracy in the horizontal direction was better than 10 mm and the vertical direction was about 14 mm.The results of baseline statistics showed that BDS had lower ability to detect weak signals than GPS system,but it was still able to accurately reflect the characteristics of baseline length and rate between two sites.Comparing the velocity fields obtained from BDS and GPS,the results showed that the difference of the two sets of velocity field in horizontal directions was 1～2 mm/a,and there was no systematic difference.Although BDS PPP accuracy was lower than GPS,but it could still be used to monitor the crustal motion of the large deformation area.

On January 21, 2016, a strong earthquake with a magnitude of Ms6.4 happened at Menyuan, Qinghai Province of China. In almost the same place, there was another strong earthquake happened in 1986, with similar magnitude and focal mechanism. In this paper, we analyze the characteristics of regional crustal deformation before the 2016 Menyuan Ms6.4 earthquake by using the data from 10 continuous Global Positioning System (GPS) stations and 74 campaign-mode GPS stations within 200 km of this event: (a) Based on the velocity field from over ten years GPS observations, a regional strain rate field is calculated. The results indicate that the crustal strain rate and seismic moment accumulation rate of the Qilian-Haiyuan active fault, which is the seismogenic tectonics of the event, are significantly higher than the surrounding regions. In a 20 km × 20 km area around the seismogenic region, the maximum and minimum principal strain rates are 21.5 nanostrain/a (NW–SE extension) and −46.6 nanostrain/a (NE–SW compression), respectively, and the seismic moment accumulation rates is 17.4 Nm/a. The direction of principal compression is consistent with the focal mechanism of this event. (b) Based on the position time series of the continuous GPS stations for a time-span of about 6 years before the event, we calculate the strain time series. The results show that the dilatation of the seismogenic region is continuously reduced with a “non-linear” trend since 2010, which means the seismogenic region has been in a state of compression. However, about 2–3 months before the event, both the dilatation and maximum shear strain show significant inverse trends. These abnormal changes of crustal deformation may reflect the non-linear adjustment of the stress–strain accumulation of the seismogenic region, when the accumulation is approaching the critical value of rupture.

对陆态网络腾冲台2012-07-01～2013 06-30连续重力观测资料进行处理,获得该台站观测精度及噪声水平.结果表明,腾冲台1～100 s噪声水平在9×10-8ms-2左右,100 s～100 min噪声水平在0.3×10-8ms-2左右,白噪声水平为0.509×10-8ms-2,对O1波、M2波等主要潮波振幅因子测量精度达到SG-053超导重力仪的观测量级,其中M2波振幅因子测量精度最高(为0.000 18).腾冲台可为川滇地区强震和腾冲火山活动监测、震前重力变化及相关研究提供高精度、可靠的连续重力观测资料.

汶川地震是有地震历史记载以来首次发生在大陆内部的高角度8级逆冲强震,给板内逆冲强震研究提供了许多新的课题.论文主要开展了以下两方面的研究: (1)近地表陡倾角铲形逆断层的破裂特征研究.基于龙门山断裂带中段动力学背景建立有限元模型,系统地研究近地表陡倾角铲形逆断层(本文所称近地表陡倾角铲形断层,要求近地表倾角至少≥65°)的破裂特征,并探讨了汶川地震逆冲滑动量随深度分布形态所可能蕴含的地壳信息.

对中国大陆构造环境监测网络(简称“陆态网络”)连续重力台站记录的于田Ms7.3级地震震前8d连续重力资料进行分析,分别于震前6d和2d在中国大陆不同区域发现了周期为4～8s的重力扰动信号.前者信号强度从鹤岗台经太原-银川台向西至库尔勒台逐渐减弱,形成一个条带;后者信号强度从温州-厦门台向西至襄樊-万州台逐渐减弱,形成一个区域.本研究对全面认识震前扰动现象、揭示其产生机理具有重要意义.

汶川MS8.0地震逆冲滑动量沿断层深度的分布有明显的特点,可以分解成三个破裂的滑动量叠加:深度18 km附近的底部破裂滑动、深度11 km附近的中部破裂滑动和两个局部破裂以外的主体滑动.扣除局部破裂滑动量后,沿断层走向从映秀到南坝近200 km范围内,逆冲滑动量沿断层深度的分布形态是一致的.基于滑动反演几何模型的有限元模拟显示,汶川地震逆冲滑动分布的整体性特征可能源自于断层浅部构造及巴彦喀拉块体SE向挤压强度沿断层走向上的一致性.

This paper constructs a finite element analysis (FEA)method for the numerical simulation of characteristic earthquakes,based on the wide-accepted knowledge of the shallow crustal structure and dynamic boundary conditions at the middle part of the Longmenshan fault zone.The influence of parallel thrust faults on regional seismic activity is focused on and simulated with this FEA model.The results show that the characteristic earthquake model with strict re-currence interval is not suitable for the entire fault zone which contains three parallel faults.When the distance between the faults is less than 20 km,the applicability of the characteristic earthquake model to each single fault is attenu-ated with the distance between the faults decreasing.The results based on the distribution pattern of the profile in the middle of the Longmenshan fault zone reveal that seismic activity of the back range fault is relatively independent,and the characteristic earthquake model with strict recurrence interval is not suitable for the entire fault zone and the central fault.

Thrust rupture is the initial and main course of the 2008 Wenchuan M(s)8. 0 earthquake. Its distribution on the causative fault plane with depth is inconsistent with most thrust earthquakes of plate interiors. Through numerical experiments, this work analyzes the influences of the source at the bottom, near-surface fault dipping angles and previous earthquakes on such distribution. The results show that under the intense compression from the Bayan Hara block in the northwest, the listric near-surface fault surface hampers the rupture and slip of the Wenchuan event to some extent. That the ruptures of previous thrust quakes are concentrated in the middle portion of the fault is one of the possible reasons for that the slip distribution of the 2008 Wenchuan event is different from most intraplate quakes of thrust type.

基于架设在山东荣成、云南下关、宁夏盐池、河北唐山和河南郑州的UNICORECOMM UR370型北斗接收机接收到的北斗和GPS信号,利用武汉大学自主研发的PANDA软件,对比分析了北斗导航系统与GPS精密单点定位精度.结果显示,北斗导航精密单点定位精度在水平方向为1～2 cm,垂直方向为3～4 cm;GPS精密单点定位精度在水平为亚cm级,垂直方向约为1～2 cm.虽然北斗导航系统的精密单点定位精度要低于GPS 50％,但已经能应用在定位精度要求几个cm或更低精度的领域.

基于2014年于田Ms7.3级地震周边地区的GPS连续观测站数据,得到了此次地震的近场地表运动和同震位移,分析了此次地震的地壳形变特征.结果表明,此次地震引起的地表运动显著,GPS记录到的最大位移振幅远超过最终的同震位移,其中距离震中约60km的XJYT站记录到了西向74.7mm和北向39.9mm的最大位移振幅,同震位移为西向20.0mm和北向9.8mm.2008年于田Ms7.3级地震在一定程度上触发了此次地震.