Static solution of a crack degenerated from dynamic solution of a propagating crack

ＳｔａｔｉｃｓｏｌｕｔｉｏｎｏｆａｃｒａｃｋｄｅｇｅｎｅｒａｔｅｄｆｒｏｍｄｙｎａｍｉｃｓｏｌｕｔｉｏｎｏｆａｐｒｏｐａｇａｔｉｎｇｃｒａｃｋＳｈｉ－ＹｕＬＩ（李世愚）ａｎｄＹｕｎ－ＴａｉＣＨＥＮ（陈运泰）（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ...     

Propagation of a subglacial flood wave during the initiation of a jökulhlaup

Abstract

Observations from the jökulhlaup from Grímsvötn in Vatnajökull, south-eastern Iceland, in 1996 indicate that the jökulhlaup was initiated by the movement of a localised pressure wave that travelled 50 km in 10 h from Grimsvötn to the terminus, forming a subglacial pathway along the glacier bed. Shortly after this wave reached the terminus, the jökulhlaup was flowing at a high discharge through a tunnel that would have needed much longer time to form by ice melting as assumed in existing theories of jökulhlaups. Frozen sediments formed in crevasses and frazil ice on the surface of the flood waters indicate the flow of supercooled water in the terminus region, demonstrating that the rate of heat transfer from subglacial flood water to the overlying ice is greatly underestimated in current theories.     

Linear theory of the response of a two layer ocean to a moving hurricane‡

Abstract

This paper describes the linear response of an inviscid two‐layer model of a deep ocean on an f‐plane to a hurricane translating across the surface at constant speed. The forcing is a localized, radially‐symmetric pattern of positive wind stress curl and negative pressure anomaly. Only the steady state response is considered. The principal result is the identification of an internal wake in the lee of the storm, present when the translation speed of the storm exceeds the baroclinic long wave speed. The amplitude of the wake depends on the length of time over which the stress is experienced at a given point. The angle of the wedge filled by the wake is small, an effect due to the fact that the scale of a hurricane is typically larger than the baroclinic radius of deformation. After the wake disperses, a geostrophically balanced baroclinic ridge remains along the storm track.     

Estimation of Occurrence Probability of Earthquake Intensity for a Period of Ten Years

A method of estimation of occurrence probability of earthquake intensity at a given site from the results of a ten-year scale of earthquake prediction described with a probability of occurrence in a given "prediction cell" is proposed in this paper. 2316 cities and towns in China were analyzed by using this method. The probability of intensity Ⅵ-Ⅸ were given for every city. These results can be used for the earthquake insurance, loss estimation, and planning of disaster protection.     

Hydrodynamic characteristics of Wujiangdu Reservoir during the dry season—a case study of a canyon reservoir

With the development of hydropower in the karst area of Southwest China, a series of cascade canyon reservoirs have been formed through the construction of dams. Given that hydrodynamic conditions in canyon reservoirs play a pivotal role in controlling the spatiotemporal distribution of physical and chemical properties of the stored water, hydrodynamic characteristics are of great importance in understanding biogeochemical cycles in those reservoirs. To further this understanding, a field campaign was conducted in the Wujiangdu Reservoir of Guizhou Province. It was found that from the reservoir inlet to the front of the dam, velocity(v) was negativelycorrelated and had a logarithmic relationship with distance along the ship track(s) under dry-season flow conditions[v =-0.104 ln(s) + 0.4756]. Analysis showed that dryseason flow velocity had no significant correlation with water temperature, p H, or dissolved oxygen(DO). However, when velocity decreased to 0.061 m/s, water depth increased abruptly. In addition, DO displayed a sudden drop and the trend in p H changed from increasing to decreasing, while water temperature showed an opposite trend, indicating the existence of a transition zone from the river to the reservoir.     

Features of a rare advection-radiation fog event

To investigate effects of atmospheric pollutants on fog nature, a comprehensive in situ observation project was implemented in the northern suburb of Nanjing, in December of 2006. For December 24-27 there occurred a heavy fog lasting 4 d in succession. This event is of rare characteristics, namely long persistence, high concentration, tall fog top, acid fog water and explosive growth. Detailed analysis along with the causes of the fog was presented. The evidence suggests that the fog was generated by nighttime radiative cooling, maintained and developed under effects of warm, wet advection. As a result, it is an advection-radiation fog event.     

Scenarios of the spread of a waste heat discharge in a river — Vistula River case study

The problem of two-dimensional mathematical modelling of heated cooling water discharges into running waters is considered in the paper. Two models — one for the evaluation of 2D turbulent velocity field and the other, developed by authors of the study, for 2D heat transport in open-channels — were used in the calculations. Relevant scenarios of the spread of heated water discharged from a designed gas-stem power plant to be constructed at the Vistula River were presented. Environmentally most friendly variant of the discharge of the thermal pollution was selected from among four various variants.     

Asymptotic Properties of a Nonlinear αΩ-Dynamo

We discuss various asymptotic regimes of kinematic nonlinear -dynamos in a thin differentially rotating shell as well as conditions for the applicability of the corresponding asymptotic solutions.     

Study of a 3-D seismic gap

Ｓｔｕｄｙｏｆａ３ＤｓｅｉｓｍｉｃｇａｐＹＵＡＮＱＩＮＧＺＨＵ１）（朱元清）ＣＯＮＧＪＵＮＸＩＡ１）（夏从俊）ＧＥＴＵＺＵＯＬＩ２）（左力格图）ＨＵＩＭＩＮＬＩ１）（李慧民）１）ＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕｏｆＳｈａｎｇｈａｉ，...     

Evaluation of Earthquake Losses and Establishment of a Corresponding Database System

After the Datong-Yanggao earthquake (October 1989),a special team was organized for the first time by the SSB of China to start the work of earthquake damage evaluation for the purpose of providing the government with a scientific basis for disaster relief.The result of the evaluation played an important role in speeding up rehabilitation and reducing damage losses in the earthquake area.Based on the evaluation of earthquake damage from the Datong-Yanggao earthquake and recent research results,this paper presents a method for quick evaluation of earthquake damages,introduces software entitled EDEP (earthquake damage evaluation program) for evaluating earthquake damage,and cites a case to explain the main function and application of the EDEP.Finally,for a quicker evaluation of earthquake damages,the paper also proposes the establishment of database systems of earthquake damage evaluation in the emphatically monitored areas and ways to build up such database systems.     

Modelling the impact of a La Niña event on a South West Pacific Lagoon

In view of increasing environmental awareness and biodiversity conservation, understanding the main forcing mechanism driving biogeochemical cycles in coral reefs and lagoon coastal areas is a priority. La Ni?a events cause unbalanced situations in the Equatorial Pacific and result in enhanced precipitation in South West Pacific coastal areas. We investigated the impact of heavy rainfalls during the 2008 La Ni?a event on the New Caledonia lagoon using a 3D coupled on-line hydrodynamic-biogeochemical model. Simulations and data showed that the whole lagoon was impacted by river inputs and stronger hydrodynamics, enhancing chlorophyll-a concentration by a factor between 1.7 and 1.9. The coupled model provided new insights into plume transport, highlighting that eastern plumes can be advected northwards or can reach the South West Lagoon, depending on the balance between regional, tide-induced, and wind-induced surface currents. It also provided a synoptic view of lagoon biogeochemical-hydrodynamic response, when remote sensing data are not available due to cloud coverage.     

Störmer method for a problem of point injection of charged particles into a magnetic dipole field

The problem of point injection of charged particles into a magnetic dipole field was considered. Analytical expressions were obtained by the Störmer method for regions of allowed pulses of charged particles at random points of a dipole field at a set position of the point source of particles. It was found that, for a fixed location of the studied point, there was a specific structure of the coordinate space in the form of a set of seven regions, where the injector location in each region corresponded to a definite form of an allowed pulse region at the studied point. It was shown that the allowed region boundaries in four of the mentioned regions were surfaces of conic section revolution.     

Solution of a Green’s function for a saturated porous medium in a half-space subjected to a torsional force

Based on the solutions of the Green’s function for a saturated porous medium obtained by the authors,and using transformation of axisymmetric coordinates,Sommerfeld integrals and superposition of the influence field on a free surface,the authors have obtained displacement solutions of a saturated porous medium subjected to a torsional force in a half-space.The relationship curves of the displacement solutions and various parameters(permeability,frequency,etc.)under action of a unit of torque are also given in this paper.The results are consistent with previous Reissner’s solutions,where a two-phase medium decays to a single-phase medium.The solution is useful in solving relevant dynamic problems of a twophase saturated medium in engineering.     

Selecting a method for interpreting GPS measurements of geodynamic movements of a point of the Earth’s surface in the high-frequency range

Different variants for interpreting the data of vertical and horizontal channels of GPS measurements are examined during experimental works. The movements of an observation point are imitated experimentally in the vertical and horizontal directions at a geophysical observatory. The experiments are carried out on a pedestal with original benchmarks in both directions. The movements are imitated in the high-frequency range with different time values of movement from one point to another, which did not exceed 1 h. The errors in imaging movements of measurement points according to the results of interpreting the readings of GPS receivers are shown in relation to the benchmark movements of measurement points in the vertical and horizontal directions. These data are processed in the differential mode using the precise point positioning (PPP) method. The experimental results confirm that there is no potential of imaging vertical movements of the Earth’s surface caused by tidal observations according to GPS receiver data.     

The research of a solution on locating optimally a station for seismic disasters rescue in a city

ＴｈｅｒｅｓｅａｒｃｈｏｆａｓｏｌｕｔｉｏｎｏｎｌｏｃａｔｉｎｇｏｐｔｉｍａｌｌｙａｓｔａｔｉｏｎｆｏｒｓｅｉｓｍｉｃｄｉｓａｓｔｅｒｓｒｅｓｃｕｅｉｎａｃｉｔｙＱｉｎｇ－ＬｉｎＹＡＯ（姚清林）（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｌｏｇｙ，ＳｔａｔｅＳｅｉ...     

Multi-hazard performance assessment of a transfer-plate high-rise building

Many urban areas are located in regions of moderate seismicity and are subjected to strong wind. Buildings in these regions are often designed without seismic provisions. As a result, in the event of an earthquake, the potential for damage and loss of lives may not be known. In this paper, the performance of a typical high-rise building with a thick transfer plate (TP), which is one type of building structure commonly found in Hong Kong, is assessed against both earthquake and wind hazards. Seismic- and wind-resistant performance objectives are fi rst reviewed based on relevant codes and design guidelines for high-rise buildings. After a brief introduction of wind-resistant design of the building, various methodologies, including equivalent static load analysis (ESLA), response spectrum analysis (RSA), pushover analysis (POA), linear and nonlinear time-history analysis (LTHA and NTHA), are employed to assess the seismic performance of the building when subjected to frequent earthquakes, design based earthquakes and maximum credible earthquakes. The effects of design wind and seismic action with a common 50-year return period are also compared. The results indicate that most performance objectives can be satisfi ed by the building, but there are some objectives, such as inter-story drift ratio, that cannot be achieved when subjected to the frequent earthquakes. It is concluded that in addition to wind, seismic action may need to be explicitly considered in the design of buildings in regions of moderate seismicity.     

Location of Tibetan earthquakes──a nonlinear approach by a simplex optimized technique

Ｌｏｃａｔｉｏｎ　ｏｆ　Ｔｉｂｅｔａｎ　ｅａｒｔｈｑｕａｋｅｓ──ａ　ｎｏｎｌｉｎｅａｒ　ａｐｐｒｏａｃｈ　ｂｙ　ａ　ｓｉｍｐｌｅｘ　ｏｐｔｉｍｉｚｅｄ　ｔｅｃｈｎｉｑｕｅ（赵珠）（丁志峰）（易桂喜／）（王建格）ＬｏｃａｔｉｏｎｏｆＴｉｂｅｔａｎｅａ...     

Analyzing observations of multiple small center of solar flares at a wavelength of 195 Å

The duration of elementary eruption process and intervals between them for flares of different importance have been determined based on the photometric data for flares, observed by a TRACE spacecraft at a wavelength of 195 Å. It has been revealed that the values of these parameters increase with increasing flare importance. It is assumed that the appearance of elementary nonstationary flare centers correlates with the origination of solitons at self-organized criticality.     

Measurements of the solar wind over a wide range of heliocentric distances — a comparison of results from the first three Whole Sun Months

Co-ordinated observations of the Sun and inner heliosphere using a large number of space- and ground-based instruments were carried out in August–September 1996, August 1998 and August–September 1999 as the first, second and third Whole Sun Months. These observations provided unprecedented cover of the Sun and inner heliosphere at solar minimum (1996) and during the rising phase of the new solar cycle (1998, 1999). In this paper we review the observations made during the three Whole Sun Months and consider the changes in the large-scale structure of the heliosphere seen over the four years.     

Application of a time-magnitude prediction model for earthquakes

In this paper we discuss the physical meaning of the magnitude-time model parameters for earthquake prediction. The gestation process for strong earthquake in all eleven seismic zones in China can be described by the magnitude-time prediction model using the computations of the parameters of the model. The average model parameter values for China are： b = 0.383, c=0.154, d = 0.035, B = 0.844, C = -0.209, and D = 0.188. The robustness of the model parameters is estimated from the variation in the minimum magnitude of the transformed data, the spatial extent, and the temporal period. Analysis of the spatial and temporal suitability of the model indicates that the computation unit size should be at least 4°× 4°for seismic zones in North China, at least 3° × 3° in Southwest and Northwest China, and the time period should be as long as possible.