On the physical model of earthquake precursor fields and the mechanism of precursors＇timespace distribution（Ⅲ）──anomalies of seismicity and crustal deformation and their mechanisms when a strong earthquake is in prep

Ｏｎｔｈｅｐｈｙｓｉｃａｌｍｏｄｅｌｏｆｅａｒｔｈｑｕａｋｅｐｒｅｃｕｒｓｏｒｆｉｅｌｄｓａｎｄｔｈｅｍｅｃｈａｎｉｓｍｏｆｐｒｅｃｕｒｓｏｒｓ＇ｔｉｍｅｓｐａｃｅｄｉｓｔｒｉｂｕｔｉｏｎ（Ⅲ）──ａｎｏｍａｌｉｅｓｏｆｓｅｉｓｍｉｃｉｔｙａｎｄｃｒ...     

The structure features of stick-slip mechanism of the strike-slip earthquake generating structure in the interior of the Chinese mainland

ＴｈｅｓｔｒｕｃｔｕｒｅｆｅａｔｕｒｅｓｏｆｓｔｉｃｋｓｌｉｐｍｅｃｈａｎｉｓｍｏｆｔｈｅｓｔｒｉｋｅｓｌｉｐｅａｒｔｈｑｕａｋｅｇｅｎｅｒａｔｉｎｇｓｔｒｕｃｔｕｒｅｉｎｔｈｅｉｎｔｅｒｉｏｒｏｆｔｈｅＣｈｉｎｅｓｅｍａｉｎｌａｎｄＷＥＮＬ...     

Spatial distribution features of sequence types of moderate and strong earthquake in Chinese mainland

Introduction Through studying ″foreshock″ and sequence features of strong earthquakes with focal mechanism of strike-slip or thrust occurred in the shallow subduction zone or in the continental thrust belt respectively, Reasenberg (1999) suggested that precursory representation and the se- quence features are related tightly to the rupture mechanism of the mainshock. This implies that the rupture pattern of the mainshock is probably one of the important factors affecting the features of afte…     

Calculation of the parameters of georesistivi－ty anisotropy and case history of earthquake precursors

Ｃａｌｃｕｌａｔｉｏｎｏｆｔｈｅｐａｒａｍｅｔｅｒｓｏｆｇｅｏｒｅｓｉｓｔｉｖｉ┐ｔｙａｎｉｓｏｔｒｏｐｙａｎｄｃａｓｅｈｉｓｔｏｒｙｏｆｅａｒｔｈｑｕａｋｅｐｒｅｃｕｒｓｏｒｓＦＵ－ＹＥＱＩＡＮ１）（钱复业），ＹＵ－ＬＩＮＺＨＡＯ１）（赵玉林）ａ...     

Structure and physical properties of the garth＇s interior

The studies on the structure and physical properties of the Earth‘s interior done by Chinese geophysicists from 1999 to 2002 were reviewed in this paper. It includes several research areas: the structure of the Earth‘s interiors using seismic tomography, anisotropy of the upper mantle in China and its adjacent areas, quality factor Qβ for S waves, subduction zone, mantle discontinuities, physical properties of Earth‘s materials and others. The review concerns mainly the contents, the methods and the results of the studies. It can be seen that new progress in the study on the structure and physical properties of the Earth‘s interior has been made in the last 4 years in China. It is shown on three aspects: advancement made on some preexistent areas; pioneering on some new fields and new methods adopted.     

Discussion on the feature of strong earthquake: Orderly distribution in time, space and intensity before the Western Kunlun Mountain Pass M=8.1 earthquake

Introduction The Western Kunlun Mountain Pass M=8.1 earthquake occurred on November 14, 2001 is the other M=8 earthquake occurred 50 years after Dangxiong, Tibet M=8.0 earthquake in Chinese mainland. The earthquake has caused the attention of the seismologists in the following aspects: 1) The fracture length is more than 400 km, which is far away from the estimated length by the statistic empirical function between the magnitude and the fracture length (WANG, et al, 2002); 2) The aftersh…     

Source mechanism of strong aftershocks (M_s≥5.6) of the 2008/05/12 Wenchuan earthquake and the implication for seismotectonics

Dozens of >M5, hundreds of >M4, and much more >M3 aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic stations. After relocated with P arrival, the >M3 aftershocks show two trends of distribution, with most of the aftershocks located along the north-east strike consistent with Longmenshan fault system, yet there is a north-west trend around the epicenter. It seems that substantially more aftershocks occur in regions with crystalline bedro...     

The mechanism of regional gravity changes before and after the Tangshan earthquake

ＴｈｅｍｅｃｈａｎｉｓｍｏｆｒｅｇｉｏｎａｌｇｒａｖｉｔｙｃｈａｎｇｅｓｂｅｆｏｒｅａｎｄａｆｔｅｒｔｈｅＴａｎｇｓｈａｎｅａｒｔｈｑｕａｋｅＲＵＩ－ＨＡＯＬＩ（李瑞浩）ＪＩＡＮ－ＬＩＡＮＧＨＵＡＮＧ（黄建梁）ＨＵＩＬＩ（李辉）ＤＯＮＧ－ＳＨＥＮＧ...     

Application of the value of nonlinear parameters H and ΔH in strong earthquake prediction

Ａｐｐｌｉｃａｔｉｏｎｏｆｔｈｅｖａｌｕｅｏｆｎｏｎｌｉｎｅａｒｐａｒａｍｅ┐ｔｅｒｓＨａｎｄΔＨｉｎｓｔｒｏｎｇｅａｒｔｈｑｕａｋｅｐｒｅｄｉｃ┐ｔｉｏｎＰＥＩ－ＹＡＮＣＨＥＮ（陈佩燕）ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ＳｔａｔｅＳｅｉ...     

‘Thermohaline front’ off the east coast of India and its generating mechanism

Physical oceanography measurements reveal a strong salinity (0.18 psu km^?1) and temperature (0.07 °C km^?1) front off the east coast of India in December 1997. T–S diagrams suggest lateral mixing between the fresh water at the coast and the ambient warmer, saltier water. This front seems to be the result of southward advection of fresh and cool water, formed in the northern Bay of Bengal during the monsoon, by the East Indian Coastal Current, as suggested by the large-scale salinity structure in the SODA re-analysis and the anti-cyclonic gyre in the northwestern Bay of Bengal during winter. The data further reveals an offshore front in January, which appears to be the result of a meso-scale re-circulation around an eddy, bringing cold and freshwater from the northern Bay of Bengal further away from the shore. Our cruise data hence illustrates that very strong salinity fronts can appear in the Bay of Bengal after the monsoon, as a result of intense coastal circulation and stirring by eddies.     

Application of EDA technology and μClinux operating system in the earthquake precursor instruments

Using Altera's Quartus Ⅱ,Nios Ⅱ IDE and Sopc Builder development tools,the proton precession magne-tometer principle host hardware platform is designed in a cyclone Ⅱ series FPGA chip(EP2C35).The proton precession magnetometer principle host core circuit's single-chip system-logic design is achieved by building and configuring the Nios Ⅱ soft-core processor,developing the IO interface and sensor control circuits,programming some hardware units' VHDL code,for example the equal precision cymometer and the DPL...     

The slip rate and strong earthquake recurrence interval on the Qianning-Kangding segment of the Xianshuihe fault zone

IntroductionLocated in the western part of Sichuan Province, China, the Xianshuihe fault zone is a notable strong earthquake zone in the eastern Tibetan Plateau. At its northwestern end, the Xianshuihe fault zone overlaps the Ganzi-Yushu fault in a left-stepping pattern. The fault zone extends southeastwards through Luhuo, Daofu, Kangding, and Moxi and disappears near Shimian, with a total length of 400 km. The fault trends N40(-50°W in the north, and N20(-30°W to the south of Kangdi…     

Research on completeness of earthquake data in the Chinese mainland（Ⅱ）──The regional distribution of the beginning years of basically complete earthquake data

（黄玮琼）（李文香）（曹学锋）ＲｅｓｅａｒｃｈｏｎｃｏｍｐｌｅｔｅｎｅｓｓｏｆｅａｒｔｈｑｕａｋｅｄａｔａｉｎｔｈｅＣｈｉｎｅｓｅｍａｉｎｌａｎｄ（Ⅱ）──Ｔｈｅｒｅｇｉｏｎａｌｄｉｓｔｒｉｂｕｔｉｏｎｏｆｔｈｅｂｅｇｉｎｎｉｎｇｙｅａｒｓｏｆｂａｓ...     

Region-time-length algorithm and its application to the study of intermediate-short term earthquake precursor in North China

Introduction The earthquake is, in essence, the rupture process of crustal medium under the tectonic stress. Statistically, the macrofracture of homogeneous material is caused by the rapid increment of microfracture numbers and their collusion between one another. The macrofracture (development No.2 JIANG Hai-kun, et al: RTL ALGORITHM IN EARTHQUAKE PRECURSOR 165of main fault) is resulted from the avalanche-like growth of microf…     

Some evidences for earthquake occurrence in the shallow crust in some areas of North China and Southwest China

IntroductionThe hypocentral location parameters (the longitude and latitude of epicenter and the focal depth) are important fundamental data for the study of seismology and the earth interior physics. To locate the seismic source precisely is the basis for the study of seismicity patterns, relation between earthquake and active structures, engineering seismology, etc (WANG, et al, 1995). Among these parameters, the precise measurement of focal depth is closely related to the correct understa…     

An overview on shallow strong earthquake activity and earthquake live losses of Chinese mainland in the centenary from 1901 to 2001

Introduction It is well known that China locates in the southeastern part of Eurasian Plate, which subjects to the action of westward subducting of Pacific Plate and Philippine Sea Plate, and northward col- lision of Indian Plate. So China is a country with strong seismicity. There are two kinds of earth-quake activities in China. In the Chinese mainland most of the earthquakes belong to the intraplate ones, and in Taiwan of China belong to interplate ones. According to the statistics 9…     

ULF electromagnetic precursors before the 1999 Jiji, Taiwan, earthquake and the comparison with results of simulating experiments

There are many reports about the abnormal electromagnetic signals observed before great earthquakes. In particular, the signals of electromagnetic anomalies before the Hyogo-Ken Nanbu, Japan, MS=7.2 earthquake on January 17, 1995 (Hayakawa, et al, 1996) and those before the Loma Prieta, USA, MS=7.1 earthquake on October 19, 1989 (Fraser-Smith, et al, 1990) are especially remarkable. However, what the above authors reported are only the phenomena of one or two observatories. In order to …     

On the dissipation of atmospheric alfvén waves in uniform and non-uniform magnetic fields

Abstract

We deduce the dissipative Alfvén wave equation in a medium stratified in one direction, with a transverse magnetic field, in the presence of dissipation by fluid viscosity and electrical resistance; the dissipative Alfvén wave equation generalizes earlier results for homogeneous (Cowling, 1960) and inhomogeneous (Campos, 1983a) media, and corrects an error in the literature (Heyvaerts and Priest, 1983). The wave equation is solved exactly in two cases: a uniform magnetic field, and a magnetic field decreasing with height. In both cases the mean state is assumed to be isothermal, with a constant rate of ionization, so that the magnetic diffusivity is constant, but the dynamic viscosity increases with height. There are therefore two regions, a low- (high-) altitude region where electrical resistance dominates fluid viscosity (or vice versa), and an asymptotic regime relevant to the uppermost (lowermost) layers. The two regions are separated by a transition layer, across which the wave field is continuous and whose structure is expressible by hypergeometric functions, with different arguments in the low- and high-altitude regions, and over the whole altitude range. These exact solutions allow the amplitude and phase of the wave field to be plotted as a function of height for a variety of magnetoatmospheric mean states. They show that wave dissipation is more localized and intense when the magnetic field decreases with height than when it is uniform.     

On conditions of magmatism origin and role of volcanic activity in the thermal regime of Earth’s crust

Bulletin of Volcanology -