Distribution of empirical recurrence intervals for segment-rupturing earthquakes onactive faults of the Chinese mainland

For the two main recurrence behaviors of segment-rupturing earthquakes on active faults of the Chinese mainland,this paper establishes corresponding empirical distributions forearthquake recurrence interval. The results show that, for the time-predictable recurrence, the normalized recurrence interval, T/Tt, obeys very well the lognormal distributions: LN (μ1=0.00, σ21 =0. 152), where, T is an observed recurrence interval, and Tt is the average recurrence interval that is correlative with the size of the preceding event. For the quasi-periodic recurrence, the normalized recurrence interval, T/T, follows the lognormal distribution : LN(μq=0.00, σ2q=0.242), where, T is the median of recurrence intervals for various cycles. A statistical test suggests that, there is no significant difference between the latter distribution, built by this paper, and the recurrence interval distribution for the characteristic earthquakes of the Circum-Pacific Plate boundaries (NB model). Accordingly, this paper combines these two distributions into one and obtains a more stable lognormal distribution :LN (μ = 0.00, σ2 = 0.222), for the quasi-periodic recurrence interval.

Statistical features of aftershock distribution size for moderate and large earthquakes in Chinese mainland

Based on data of earthquake sequences with Ms≥5.0 in Chinese mainland from 1970 to 2004, for different sequence types and different rupture modes of the main shock, the relationship between aftershock distribution size R and the magnitude of the main shock Mo has been studied statistically. Considering the rupture mode of the main shock, we give the quantitative statistical relationships between R and Mo under 95% confidence level for different sequence typos. Qualitatively, lgR, the logarithm of the aftershock distribution size, is positively correlative to the M0, but the data distribution is dispersed. Viewing from different sequence typos, the correlation between R and M0 is very weak for isolated earthquake type （lET） sequence, R distributes in the range from 5 to 60 km; For mainshock-aftershock type （MAT）, lgR is positively correlative to M0; For multiple main shock type （MMT）, the corelation between lgR and M0 is not very obvious when M0≤6.2 and R distributes in the range from 5 to 70 km, while it shows a linear correlation when M0≥6.3. The statistical results also show that the occupational ratios of different sequence types for strike-slip and oblique slip are almost the same. But for dip-slip （mostly are thrust mechanisms）, the ratio of MAT is higher than that of IET and MMT. Comparing with previous results, it indicates that, when M0 is large enough, R is mainly determined by M0 and there is almost no relationship with the rupture mode of the main shock.

First record of Ulva californica in the mainland of China:a single alien parthenogenetic population in discontinuous distribution

Molecular investigations have raised concerns about the ecological risks of green tides caused by alien Ulva species in new habitats.The green tide-forming species U.californica Wille was generally considered to be native to North America,but new records have been widely reported in Europe,Asia,and Oceania in recent decades,indicating a strong dispersal capacity of the species.In this study,the first record of U.californica on the coastline of China's Mainland was reported,following a combined identification with multi-molecular markers and morphological characterization.It was shown that this species has a discontinuous distribution pattern along the coast of China's Mainland,with northern populations in the Yellow Sea and southern populations in the East China Sea and South China Sea.According to results of examination for life cycles and identification with mating type(MT)genetic markers,it was indicated that all U.californica samples were male gametophytes,and reproduced themselves through parthenogenesis solely.Combined with the fact that southern and northern populations are highly genetically identical,here we believed that U.californica was a recent alien species to China's Mainland with a rapid local spread.This finding provided evidences that the ability to reproduce in a variety of ways may play an important role in the spread of Ulva species,as well as essential basic data for marine risk management of green tides in China.In addition,according to the phylogeographic analysis,the possible geographical origin and global dispersal routes of U.californica were also proposed.

Research on Strong Earthquake Tendency on Active Tectonic Block Boundaries in the Chinese Mainland

Previous studies have shown that the active tectonic block boundaries in the Chinese mainland are the main belts and concentration areas of strong earthquakes occurring in the Chinese mainland.It is essential to carry out follow-up analysis of strong earthquake risk of active tectonic block boundaries.In this paper,we carry out the analysis on the tendency of strong earthquakes along each active tectonic block boundary from three aspects respectively,including the evolutionary characteristics of the Load/Unload Response Ratio time series,the probability method based on the log-normal distribution function,and variation of b value.The estimation of strong earthquake criticality on each active tectonic block boundary is done based on the evolutionary characteristics of the Load/Unload Response Ratio time series,the cumulative probability and conditional probability,and the decrease of the b value.Finally,according to the results of analyses on the above three aspects,the potential strong earthquake areas in the forthcoming 5 years in the Chinese mainland are discussed.

Study on the regional deviation of the mac-roscopic epicenters from relevant epicenters by rapid determination in Chinese mainland

The primary results have been obtained by the analyses on the deviation of macroscopic epicenters from relevant microscopic epicenters determined rapidly after the 139 earthquake events occunrred during 1989-2004. Further study has proved the normal distributions exist in both the east and west parts of Chinese mainland partitioned along meridian 105°E. The empirical two-dimensional normal distribution functions for the deviations are presented in the paper. The results are of significance in reducing uncertainty of losses assessment immediately after a destroyed earthquake.

全球火山活动时空分布特征及其对强震活动趋势的指示

基于史密森学会火山目录分析了全球火山活动的时空特征,并结合中国地震台网目录讨论了火山活动对全球和中国大陆强震活动趋势的指示意义。结果显示:①全球火山活动表现出较为显著的百年周期特征,且百年周期内火山活动和M≥8.0大震之间存在着频次准同步和能量互补现象;②中国大陆1955年前后强震活动状态的变化可能与同期全球火山活动状态变化密切相关,且二者可能受控于百年周期内地球内部能量积累与释放的状态变化;③2022年汤加火山的剧烈喷发意味着地球内部能量仍在持续释放。结合全球M8地震和中国大陆M7浅源地震的活动特征,认为当前及未来一段时间全球及中国大陆的大震活动状态可能与二十世纪上半叶相似。

更好发挥新型城镇化对中国式现代化的支撑作用

城镇化是现代化的必由之路,以人为本的新型城镇化是中国式现代化建设的强大推动力量。当前,我国城镇化已迈入快速发展的中后期,将呈现城镇化速度放缓、效应累加释放、空间高效集聚、城市体系分化、城市品质提升等“五期叠加”典型特征。同时,我国城镇化亟待解决近3亿农民工市民化、近1.5亿新增城镇人口空间分布、城市发展动能接续培育、超大特大城市面临多重风险等重大战略问题。未来一段时期,需要聚焦重点,积极稳妥推进以人为本的新型城镇化:以推进城镇基本公共服务常住人口全覆盖为重点,提高农业转移人口市民化质量;以城市群、都市圈为依托,构建大中小城市协调发展格局;以提升城市规划、建设、治理水平为重点,打造宜居、韧性、智慧城市;以畅通城乡要素流动为重点,深入推进城乡融合发展。

Contribution to the knowledge of the crane fly genus Helius(Diptera: Limoniidae) from Sichuan, China

Specimens of the crane fly genus Helius Lepeletier&Serville,1828 from Sichuan,China are examined and studied.Three Helius species all belonging to the nominotypical subgenus are recognized,of which H.(H.)pallidissimoides Xu,Ma&Zhang,sp.nov.is described and illustrated as new to science,and H.(H.)pallidissimus Alexander,1930 and H.(H.)franckianus Alexander,1940 are redescribed and illustrated.For the first time,descriptions and illustrations are provided for the male of H.(H.)pallidissimus and the female of H.(H.)franckianus.

华东地区维管植物新纪录

通过野外调查和标本查阅,确定了1个中国大陆种子植物新纪录种,即台湾通泉草(Mazus fauriei),凭证标本存放于上海辰山植物园标本馆(CSH)。确定了2个江西省蕨类植物新纪录,即无腺姬蕨(Hypolepis polypodioides)和三角鳞毛蕨(Dryopteris subtriangularis)。凭证标本存放于中国科学院庐山植物园标本馆(LBG)。

中国内地鸟类新记录——红脚斑秧鸡

2023年6月9日,在广东大亚湾水产资源省级自然保护区开展野生动物监测中记录到红脚斑秧鸡(Rallina fasciata),经查阅文献,确定该种为中国内地鸟类新记录。

不同地质成因岩石地应力分布规律的统计分析

通过收集我国大陆地区大量的实测地应力资料,筛选出了受局部影响小的实测数据,建立了岩浆岩、沉积岩和变质岩地应力随埋深分布的散点图,并根据各自的分布规律进行了相应的回归分析。结果发现,三大类岩石的地应力分布规律存在差异,其主要与岩石地质成因相关。三大类岩石的垂直应力总体上随埋深呈线性增大,量值接近各自上覆岩层自重;最大水平主应力随埋深均呈线性增大,相同埋深条件下,火成岩量值最大,变质岩次之,沉积岩最小;而沉积岩浅部最小水平应力大于岩浆岩;三大类岩石的水平差应力总体上随埋深也呈线性关系,相同埋深条件下,火成岩较大,而沉积岩较小;浅部岩浆岩平均水平主应力与垂直应力之比最大,而沉积岩较小。

中国大陆中强以上地震余震分布尺度的统计特征

依据1970年以来记录相对完备的Ms≥5.0地震序列资料,统计研究了中国大陆余震分布尺度与序列最大地震震级M0及最大地震破裂形式之间的关系.在95%置信概率下,考虑主震破裂形式,分序列类型给出了余震分布尺度与M0之间的统计关系.定性而言,余震分布尺度的对数lgR与M0正相关,但数据分布较为离散.分类型来看,孤立型序列余震分布尺度与M0之间统计相关程度低,余震分布尺度介于5～60 km之间;主余型序列lgR与M0正相关;多震型序列当M0≤6.2时lgR与M0之间相关性不显著,余震分布尺度介于5～70km之间,当M0≥6.3时lgR与M0线性相关.统计结果还表明,走滑-近走滑及斜滑型主震所导致序列类型比例之间没有显著差异,而倾滑-近倾滑型主震（主要为逆断型破裂）所导致的主余型序列所占比例较高,孤立型及多震型序列所占比例则相对较低.对比研究显示,当M0较高时,余震分布尺度主要取决于主震大小而与主震破裂形式关系不明显.

浙江舟山东福山岛种子植物区系初探

在实地调查的基础上,对浙江舟山东福山岛的植物多样性及区系组成进行了分析研究。结果表明:东福山岛共有野生种子植物133种,隶属于53科101属,最大科(物种数≥5)排序为菊科Compositae,蔷薇科Rosaceae,毛茛科Ranunculaceae,桑科Moraceae和大戟科Euphorbiaceae,多数为世界广布性成分;在中国15个分布区中占有11个区系类型,总体数量相对同纬度中国大陆贫乏,其中泛热带分布、北温带分布占主体,东亚分布为辅。热带成分共60属,占总属的59.41%,温带成分共41属,占总属的39.81%,表现从热带向温带过渡的趋势,说明地理成分具有一定起源复杂性,符合海岛植物丰富度少于大陆的植物地理学一般规律;海滨植物区系发达,但缺乏起源古老的孑遗植物,与日本植物区系亲缘关系密切,同时归化植物种类日渐增多,还印证中国大陆物种新分布2种,发现中国大陆物种新分布3种,发现浙江新分布1种。

中国大陆地震灾害生命损失时空特征分析

以1966-2016年中国大陆地震灾害生命损失数据为研究对象,基于GIS平台定量分析中国大陆地震灾害生命损失时空分布特征。研究结果表明:(1)中国大陆造成生命损失的地震次数为143次,占成灾地震(有经济损失或人员伤亡的地震)的25%。成灾地震平均每年发生9. 45次,而造成人员死亡的地震平均每年发生2. 38次。(2)中国大陆致死性地震造成的死亡人数突出,重特大地震对累计地震死亡人数作用明显,地震灾害生命损失呈高度集中的特点。(3)中国大陆地震灾害分布广,大陆31个省市自治区中28个省份发生过成灾地震,因地震导致有人员死亡的省份有18个,其中河北省、四川省、云南省因地震灾害导致的累计人员死亡占全国的比例高达90%。地震灾害总体呈现中小地震在多震省份生命损失较小,在少震省份生命损失反而较大。(4)50年中国大陆地震灾害累计人员死亡高达34. 66万人,其中城市直下型地震贡献率高达71%。(5)地震灾害生命损失分布受人口密度影响显著,以人口分界线"胡焕庸线"为界,呈现东高西低,与地震发生频次相反。

中国大陆归化植物新记录

报道了中国大陆归化植物新记录刺毛峨参(Anthriscus caucalis M.Bieb.)和印加孔雀草(Tagetes minuta L.),并进行了形态描述,提供了凭证标本和活植物照片。

北京2种鸟类的新分布记录

Two new records of birds occurred in Beijing are reported. Two flocks of Chinese Bulbul (Pycnontus sinensis sinensis) composed of 38 individuals were found in Hongluosi of Huairou County in September 26—27, 2002. One male Red-winged Crested Cuckoo ( Clamator coromandus ) was observed in Xiaolongmen Wood Farm of Mengtougou District on May 23, 2000. Further surveys indicate that Chinese Bulbul is a resident species of birds in Beijing, the distribution sites include Haidian, Shunyi, Huairou and Fangshan; while Red-winged Crested Cuckoo, a summer visitor, arrives in Beijing in the middle ten days of May and migrates southward in early September. These findings together with the records of Crossoptilon mantchuricum, Ficedula mugimaki, Fringilla coelebs coelebs, F. beijingnica, Phylloscopus sichuanensis since 1990 have increased the bird species living in Beijing from 344 to 351. Habitat restoration and intensive surveys may increase avian species diversity of Beijing.

中国新移民的类型和分布

1970年代以来的中国新移民,是国际移民潮的组成部分。中国新移民主要由留学人员、非熟练劳动力、商务移民、劳务人员和非法移民组成。迄2008年,其数量达1000万以上。大规模的中国新移民潮,极大地改变了华侨华人的数量和分布,全世界华侨华人数量增至4500万以上,北美、欧洲、大洋洲成为中国新移民的目的地。

中国大陆活动地块边界带强震趋势研究

已有研究表明,中国大陆活动地块边界带是我国大陆强震的主体带和集中区,因此有必要对各边界带开展强震危险性的跟踪分析。本文分别从加卸载响应比时序演化特征、基于对数正态分布的概率方法和b值变化特征3个方面对各边界带未来强震趋势进行了分析;并分别根据加卸载响应比时序演化特征、综合累积概率与条件概率、b值下降判断了各边界带未来发生强震的危险程度。最后,根据3种方法的分析结果,探讨了中国大陆未来5年发生强震的可能区域。

华人新移民研究

华人新移民包括自20世纪50年代以来的中国大陆移民、台港澳移民和东南亚华人二次移民。本文拟探讨 华人新移民的分布、特点、新移民内部以及新、老移民之间的关系。笔者认为国际移民是经济全球化的一个重要因素,在 地区间经济发展不平衡的情况下,跨国移民将不断增加。华人新移民是国际移民的一个重要组成部分,她改变了海外华人 分布的格局,赋于海外华人新的特点,并为移居国和祖籍国的经济、社会和文化的发展作出了巨大的贡献。

100多年来中国城市空间分布格局的时空演变研究

文章剖析100多年来中国城市空间分布格局的演变特点、成因,并展望演变趋势。对城市人口密度、非农人口规模、CD值和城市规模结构的综合分析表明,中国城市空间格局具有东密西疏、呈三级阶梯状分布、省际差异大、交通指向明显的特点。这种地带性差异由来已久,是自然环境、政治、经济、社会和外部环境等因素长期综合作用的结果。这些要素在空间上存在很大差异,且要素协同作用时,具有惯性和马太效应,中国未来城市空间格局的差异仍将持续存在,并有可能扩大,东部沿海新城市空间将成为未来城市格局的主体。