Studies on seismic source

During the period of 1999-2002, the Chinese seismologists made a serious of developments in the study on seis-mic sources including observations, experiments and theory. In the field of observation, the methods of the accu-racy location of earthquake sources, the inversion of seismic moment tensor and the mechanism of earthquake source are improved and developed. A lot of important earthquake events are studied by using these methods. The rupture processes of these events are inverted and investigated combined with the local stress fields and the tec-tonic moment by using the measurements of surface deformation. In the fields of experiments and theory, many developments are obtained in cause of seismic formation, condition of stress and tectonics, dynamics of earthquake rupture, rock fracture and nucleation of strong earthquakes.     

Studies on seismic waves

The development of seismic wave study in China in the past four years is reviewed. The discussion is divided into several aspects, including seismic wave propagation in laterally homogeneous media, laterally heterogeneous me-dia, anisotropie and porous media, surface wave and seismic wave inversion, and seismic wave study in prospect-ing and logging problems. Important projects in the current studies on seismic wave is suggested as the develop-ment of high efficient numerical methods, and applying them to the studies of excitation and propagation of seis-mic waves in complex media and strong ground motion, which will form a foundation for refined earthquake haz-ard analysis and prediction.     

Seismic Studies of the Earth’s Core

Izvestiya, Physics of the Solid Earth - Abstract—The paper presents the review of the conceptually most important results of seismological studies of the Earth’s core and their...     

Magnetotelluric Studies of Active Continent–Continent Collisions

Continent–continent collisions are an important tectonic process and have played a fundamental role in the evolution of the modern continents. A combination of geological and geophysical data has provided new constraints on the structure and temporal evolution of these orogens. Magnetotelluric (MT) studies have been an important part of these studies since they can constrain the fluid content and thermal structure which are key parameters for defining the rheology of the crust and upper mantle. MT studies of the Himalaya have defined the geometry of active faults associated with continued plateau growth. Orogen scale MT studies have shown that both the India–Asia collision (Tibetan Plateau and Himalaya) and the Arabia–Eurasia collision (Eastern Anatolia) have developed a low resistivity mid-crustal layer with upper surface at 10–20 km that is likely due to a combination of partial melt and associated aqueous fluids. The properties of this layer are consistent with a strength contrast that permits crustal flow over geological timescales. The upper mantle from the Moho to at least 100 km beneath both Northern Tibet and the Anatolian Plateau is characterized by low resistivity values (10–30 Ωm) indicating the presence of shallow asthenosphere. Future integrated seismic and MT studies of collision zones are needed fully to explore the 3D structures associated with deformation and further constrain geodynamic models.     

Seismic Observations and Seismic Hazard Studies in the Philippines

It has taken more than a hundred years for seismic observations in the Philippines to evolve to a modern observation system.The responsibility of seismic observations was likewise transfeered from one agency to another during this same period of time.At present,the mandate of conducting seismic observatins in the Philippines rests with the Philippine Institute of Volcanology and Seismology(PHIVOLCS),In 2000,through a grant aid from the Japan International Cooperation Agency(JICA),the Philippine Seismic netowrk was upgraded to a digital system.As a result,a new set of seismic monitoring equipments was installed in all of the 34 PHIVOLCS seismic stations all over the country,Digital waveforms are now available for high level seismic data processing.and data acquisition and processing are now automated.Included in the upgrade is the provision of strong motion accelerographs in all stations whose data can now be used for studying ground motion and intensity attenuation relations,The new setup is now producing high-resolution data that can now be used for conducting basic seismological researches,Earthquake locations have now improved allowing for the modeling and delineation of earthquake source regions necessary for earthquake hazard studies.Current seismic hazard studies in the Philippines involve the estimation of ground motion using both probabilitstic and deterministic approaches,seismic microzonation studies of key cities using microtremor observations,paleoseismology and active faults mapping ,and identification of liquefaction-prone,landslide-prone nd tsunami-affected areas.The earthquake database is now being reviewed and completed with the addition of historical events and from data from regional databases,While studies of seismic hazards were primarily concentrated on a regional level ,PHIVOLCS is now focusing on doing these seismic hazard studies on a micriolevel.For Metro Manila,first generation hazard maps showing ground rupture,ground shaking and liquefaction hazards have recently been completed.Other large cities that are also at risk from large earthquakes are the next targets.The elements at risk such as population,lifelines,and vertical and horizontal structures for each of these urban centers are also being incorporated in the hazard maps for immediate use of planners,civil defense officials,policy-makers and engineers.The maps can also now be used to describe possible scenarios during times of strong events and how appropriate socio-economic and engineering responses could be designed.In addition,a rapid earthquake damage assessment system has been started which will attempt to produce immediate or rapid assessments identification of elements at risk durin times of strong earthquakes     

Studies of Earthquake Hazard Using Microseismicity Data in Modern Times

This paper selects some representative regions to obtain their G-R relation curves according to their seismicity characteristics,by using ML≥2.0 microseismicity data(1970~1993)in North China.The annual occurrence rate of events of each magnitude can be inferred from the G-R relation.At the same tune,the actual annual occurrence rate of earthquakes of higher magnitudes can be calculated from historical earthquakes(1300-1993)recorded in the same region.It seems that both results are almost the same.Therefore,the rate of events of higher magnitudes can be obtained by using microseismicity data when the proper region is selected.However,two points should be noticed:(1)The method can only give the annual occurrence rate in a seismicity system and estimate the whole situation of the system.(2)When there is a very large earthquake in and near the period in which the microseismicity data are applied,the actual occurrence rate of the system,including this larger earthquake,cannot be obtained by this method.     

Studies and experiments on earthquake prediction during 1999～2002

This paper briefly reviewed the research progresses of earthquake prediction and/or forecasting in China during 1999～2002, especially focused on mid-short term prediction methods with approaches of seismicity, crustal de-formation, electromagnetism, ground water and the analysis by synthesis, and the application of the methods to the practice of earthquake prediction.     

Studies on structural vibration control with MR dampers using μGA

A new approach to reducing the seismic response of spatial structures with magneto-theological （MR） dampers is presented in this paper. The Genetic Algorithm with small populations （μGA） is used to optimize the control for the MR dampers to reduce structural vibration, which is difficult to achieve using classical optimal control. The advantages of μGA are the use of global properties and that fewer conditions are required to obtain the optimal function. Numerical results demonstrate the effectiveness of the proposed method in reducing the seismic response of structures.     

Studies on structural vibration control with MR dampers using μGA

A new approach to reducing the seismic response of spatial structures with magneto-rheological (MR) dampers is presented in this paper. The Genetic Algorithm with small populations (μGA) is used to optimize the control for the MR dampers to reduce structural vibration, which is difficult to achieve using classical optimal control. The advantages of μGA are the use of global properties and that fewer conditions are required to obtain the optimal function. Numerical results demonstrate the effectiveness of the proposed method in reducing the seismic response of structures.     

Application of Fracture Gas Measurement to the Earthquake Studies in China

The earth is an enormous open system and the gas-releasing phenomenon of the crust is the major means of exchange of matters and energy at different crustal depth.Therefore,a powerful gas-releasing channel is actually a "window" to understand the subterranean physical and chemical variations as well as stress-strain changes.The releasing places,quantities and ways obtained by systematically observing and recording can reveal the pressure variation and opening state of channels in the crust,and furthermore provide important information for earthquake prediction,tectonic activity and monitoring of volcanic activity.The fracture-gas measurement has been applied widely to earthquake sciences and has played an important role.The authors introduced systematically the application situation and preliminary achievements in China,and pointed out that though this technique is at the beginning stage and not very sophisticated but its capacities for being easy-carrying,fast-operating and inexpensive,makes for a prom     

Progress in Earthquake Studies in China for the Past 30 Years

Progress and application of earthquake studies are important and effective fundamentals for the improvement of earthquake prevention and disaster reduction. Through industrious effort during the past 30 years, significant advances were made in understanding the rules of earthquake occurrence, and the mastering and applying of the technology of earthquake prevention and disaster reduction. A number of devices that come close to or reach advanced world levels have been established and some systems in seismological experiments and earthquake prevention work have been improved, the ability to test and identify earthquake precursors have been raised, and the understanding of the complexity of these precursors has been deepened. The practical indexes and approaches for earthquake prediction have been worked out, and remarkable achievements in predictions and prevention of major earthquakes have been     

How to Find Aquifer Statistics Utilizing Pumping Tests? Two Field Studies Using welltestpy

We present a workflow to estimate geostatistical aquifer parameters from pumping test data using the Python package welltestpy . The procedure of pumping test analysis is exemplified for two data sets from the Horkheimer Insel site and from the Lauswiesen site, Germany. The analysis is based on a semi-analytical drawdown solution from the upscaling approach Radial Coarse Graining, which enables to infer log-transmissivity variance and horizontal correlation length, beside mean transmissivity, and storativity, from pumping test data. We estimate these parameters of aquifer heterogeneity from type-curve analysis and determine their sensitivity. This procedure, implemented in welltestpy , is a template for analyzing any pumping test. It goes beyond the possibilities of standard methods, for example, based on Theis' equation, which are limited to mean transmissivity and storativity. A sensitivity study showed the impact of observation well positions on the parameter estimation quality. The insights of this study help to optimize future test setups for geostatistical aquifer analysis and provides guidance for investigating pumping tests with regard to aquifer statistics using the open-source software package welltestpy .     

Bemerkungen zu T.E. Aurén,Studies of Solar Radiation 1951

Zusammenfassung Die vonT. E. Aurén entwickelte Methode, aus einer grossen Anzahl von Messungen der Totalstrahlung der Sonne Kurven der mittleren Maxima zu gewinnen, wird befürwortet. Diese Kurven repräsentieren die für jeden Messort charakteristische, optimale Durchlässigkeit der Atmosphäre. Sie können daher auch als strahlungsklimatischer Parameter verstanden werden, sei es etwa als Intensität des solaren Strahlungsstromes bei bestimmten Höhenwinkeln, oder als Tagessummen usw.     

Basic Environmental–Hydrogeological Studies in the Territory of European Russia Affected by Chernobyl Accident

Water Resources - A procedure for assessing the protection of groundwater against pollution is considered. This is a basic procedure for tentative forecast estimates of changes in the...     

Thermal Regime of the Earth’s Lithosphere and the Mantle: Geothermal Studies at IPE RAS

Izvestiya, Physics of the Solid Earth - This paper is devoted to the historical development of geothermal research in the former Soviet Union. The history of the Laboratory of geothermics at the...     

Ecological–Microbiological Studies of Lake Beloe in Winter and Spring with the Use of Innovation Test-Systems

Water Resources - Chlorophyll a concentration, the total abundance of bacteria, the number of bacterial cells with active metabolism, and the abundance of saprotrophic bacteria were studied in the...     

Studies on the Surface Rupture Zone of 1303 Hongdong Earthquake of M =8 and Paleoearthquakes of Huoshan Fault in Shanxi Province

An earthquake of M=8 occurred in the Linfen Basin of the Shanxi graben system in 1303,producing a surface rupture zone about 45km long.Compiling a geological map at 1:10,000 and studying in detail the rupture zone,its dextral strike-slip displacement is determined to be 4-8.6 m,and normal dip-slip displacement up to 3.5-5 m.In this paper the geochronological evidence for the formation of the surface rupture zone is provided and the Huoshan fault is confirmed to be the seismogenic structure for the M=8 earthquake.Field trenching enables us to identify two paleoseismic events having occurred along the Huoshan fault since the middle Holocene before the M8 earthquake.A recurrence interval of these three events including 1303 Hongdong M 8 earthquake is determined to be up to 1500-2000 years.The result corresponds to the mean recurrence interval calculated from slip rate on the Huoshan fault during Holocene.     

Corona Satellite Pictures for Archaeological Studies: A Review and Application to the Lost Forbidden City of the Han–Wei Dynasties

This paper provides a state of the art of the use of declassified satellite Corona for archaeological application and deals with the use of historical archives of Corona and aerial photographs for detecting ancient hidden cultural relics that may be completely lost in the modern landscape veiled by current land uses and land covers. Geospatial analysis is adopted to identify, extract and map the subtle archaeological features and cultural landscape of the lost Han–Wei Forbidden City in the Henan Province (China). It was one of the most important cities of ancient China, served as the capital for a long period, from the Eastern Zhou (2600 BP, Zhou Dynasty) to the Eastern Han and Wei Dynasties (1900–1500 BP). Outputs from our investigations clearly provided evidence of numerous buried structures of potential archaeological interest that were compared with historical documentation and excavations carried out in the area. The geospatial analysis, applied both to aerial photograph and to Corona pictures, enabled us to discover a number of unknown sub-palaces and structures, thus providing new insights for this important archaeological area.     

Studies of Trends in the Upper Atmosphere for Improving Diagnosis and Forecasts in the Helio–Geophysical Service of the State Committee on Hydrometeorology

A brief review of the current state of studies of long-term trends in the middle and upper atmosphere and ionosphere is presented. It is shown that the present trends in the density and temperature of the upper atmosphere and parameters of the ionospheric layers may lead to changes in the aforementioned spheres. It would be necessary to take into account these trends in applied problems related to planning space vehicle orbits, propagation of radio waves, measurements at low-orbiting satellites, and so on. It is emphasized that the Helio–Geophysical Service of the State Committee of Hydrometeorology, which supplies customers with information on the state of the upper atmosphere, ionosphere, and near-Earth space, should develop information products related to possible changes in atmospheric and ionospheric parameters caused by the presence of the long-term trends.