This paper studies the temporal and spatial distribution of great global earthquakes( M W≥8.0) since 1900.We compare the two periods of upsurges of great earthquakes occurring in the middle of last century and beginning of this century.The former period took place between 1950 and 1965 during which 13 great earthquakes( M W≥ 8.0) occurred,including three events with moment magnitude greater than 9.0.The largest magnitude in this period reached 9.6.The latter period starts from the beginning of this century.In less than 12 years,15 great earthquakes have attacked the world with the largest magnitude being M W9.1.On the basis of comparison between these two upsurges of global earthquake activity,we infer that the ongoing high level of earthquake activity may continue for another five years or so.Numerous great earthquakes( M W≥8.0) and many large earthquakes( M W6.0~7.0) will occur globally in these five years.In addition,this paper also discusses the relationships between earthquake activity along the Sumatra segment of the Indian-Australia plate boundary and that in the Bayankala block in the middle of Qinghai-Tibetan plateau as well as in the blocks of the southern plateau.The results indicate that the Qinghai-Tibetan plateau,in particular its middle and southern parts,is a likely place for future earthquakes of magnitude over 7.0. 相似文献
Decapterus maruadsi is a commercially important species in China, but has been heavily exploited in some areas. There is a growing need to develop microsatellites promoting its genetic research for the adequate management of this fishery resources. The recently developed specific-locus amplified fragment sequencing (SLAF-seq) is an efficient and high-resolution method for genome-wide microsatellite markers discovery. In this study, 28 905 microsatellites (mono- to hexa-nucleotide repeats) were identified using SLAF-seq technology, of which di-nucleotide was the most frequent (13 590, 47.02%), followed by mono-nucleotide (8 138, 28.15%), tri-nucleotide (5 727, 19.81%), tetra-nucleotide (1 104, 3.82%), pentanucleotide (234, 0.81%), and hexa-nucleotide (112, 0.39%). One hundred and thirty-two microsatellite loci (di- and tri-nucleotide) were randomly selected for amplification and polymorphism, of which 49 were highly polymorphic and well-resolved. The average number of alleles per locus was 13.63, ranging from 4 to 25, and allele sizes varied between 110 bp and 309 bp. The observed heterozygosity ( Ho ) and expected heterozygosity ( He ) ranged from 0.233 to 1.000 and from 0.374 to 0.959, with mean values of 0.738 and 0.836, respectively. The polymorphism information content (PIC) ranged from 0.341 to 0.941 (mean=0.806). However, 12 loci deviated from Hardy-Weinberg equilibrium. Furthermore, transferability tests were also successful in validating the utility of the developed markers in five phylogenetically related species of family Carangidae. A total of 48 microsatellite markers were successfully cross-amplified in Decapterus macarellus, Decapterus macrosoma, Decapterus kurroides, Trachurus japonicus, and Selaroides leptolepis. The present microsatellites provided the first known set of microsatellite DNA markers for D. maruadsi, D. macarellus, D. kurroides, and D. macrosoma, and would be useful for further population genetic and molecular phylogeny studies as well as help with the fisheries management formulation and implementation of the understudied species.
