Key elements of construction and exploitation of a land-based seismic-gravimetric complex     

D. V. Abramov  V. V. Dorozhkov  V. N. Koneshov 《Seismic Instruments》2011,47(3):253-258

Creation of a seismic-gravimetric complex that can operate automatically for several years allows one to record the movements of the test masses of seismometers and gravimeters simultaneously in different frequency bands. The overlapping of these frequencies takes place in the region of tenths of a Hertz. The seismic-gravimetric complex contains two relative CG-5 gravimeters, one absolute A10 gravimeter, one three-component Ugra seismic station, one automatic meteorological station, and a two-frequency GPS receiver. The relative gravimeters are used as the basic instrument. For these devices the problem of displacement of the gravimeter scale “zero” was solved. To perform long-term monitoring observations using the seismic-gravimetric complex, a gravimetric observatory was built in the area with a low level of technogenic noises. As a result of the preliminary geophysical observations, it turned out that the informative parameter is a root-mean-square deviation of the measured gravity force values.  相似文献   

Natural assumptions for tsunami hazard on the coast of the Khabarovsk Krai and Primorye     

G. L. Koff  I. V. Chesnokova  A. V. Kolesnikov  O. V. Pavlenko  S. G. Bashkirov  M. A. Tashmatov 《Seismic Instruments》2011,47(4):346-356

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Dangerous geological processes in the Baikal rift zone and adjacent territories     

V. K. Laperdin  V. S. Imaev 《Seismic Instruments》2011,47(2):136-147

In the context of active endogenic, exogenic, and technogenic factors, the dynamics of developing geological hazards and risks is estimated for the linear transport systems that run across the strong earthquake epicentral areas of the Baikal rift zone and adjacent territories. The presence of ancient and new seismic structures in the modern relief can be regarded as an indicator of places of intense development of exogeodynamic processes and zones of hazard.  相似文献   

The seismotectonic and macroseismic features of the Wenchuan (Sichuan) earthquake (<Emphasis Type="Italic">M</Emphasis><Subscript><Emphasis Type="Italic">S</Emphasis></Subscript> = 8.0) of May 12, 2008     

E. A. Rogozhin  Xuhui Shen 《Seismic Instruments》2011,47(2):167-179

A disastrous earthquake with a magnitude M _S = 8.0 (M _W = 7.9), in China called “the 5.12 Wenchuan earthquake,” occurred on May 12, 2008, in Sichuan province on the border between the Sino-Tibetan Mountains and the Sichuan depression. The instrumental epicenter was registered in the southeastern part of Wenchuan county, and the hypocenter depth was 14 km. As the strongest and most destructive earthquake within mainland China, it caused numerous human losses and destruction of buildings and infrastructure. The seismic effect from the main shock and aftershocks was felt in many counties, towns, and villages, though Sichuan province suffered the most. The maximum intensity of the shocks was estimated at 11 degrees, according to the Chinese macroseismic scale. In the process of source opening, from the southern part of Wenchuan county to the vicinities of Quingchuan, a seismic fault system with a total length up to 240 km out-cropped on the earth’s surface, confined to the Longmenshan fault belt. The seismic fault system disturbed the original ground, resulting in the collapse or damage to various constructions, such as buildings, homes, bridges, roads, etc. Fault offsets had a dextral strike-slip and thrust kinematic combination. The earthquake generated several tens of thousands of landslides, rockfalls, and debris flows. Many dammed ponds appeared in the epicentral zone due to the activation of landslides. Thus, the geological effects turned out to be the most destructive factor in this case. At the same time, the seismic intensity of surface shaking was abnormally low even in direct proximity to the seismic fault system. Usually it was no more than 7–8 degrees. This macroseismic phenomenon may turn out to be rather typical for many major earthquakes.  相似文献   

Modeling of changes in the tidal response of the environment to an impending earthquake     

D. S. Molodenskii 《Seismic Instruments》2011,47(3):246-252

It has become possible to apply efficiently Beaumont and Berger’s idea (1974) about the possibility to predict earthquakes using continuous monitoring of temporal variations of the tidal response only in recent years, with the appearance of GPS data on the field of the Earth’s surface displacements in seismic regions, as well as with the appearance of the Global Seismographic Network (GSN) containing the tidal tiltmetric and gravimetric data in the vicinities of the epicenters of strong earthquakes in Peru (2001), Sumatra (2004), and Chile (2010) before and after the strongest seismic events. Below, we present the results of the modeling of temporal variations of the tidal response of the environment in the vicinities of the focus of catastrophic earthquakes. The model of the focus includes data on the expansion and orientation of the fault surface, as well as on the discontinuity of the tangential component of the displacement vector on the opposite shores. The model is constructed from the GPS data on horizontal and vertical displacements of the Earth’s surface.  相似文献   

余震密度随距离的衰减不代表动态应力触发过程     

K.R.-Dinger  R.S.Stein  S.Toda  魏志恒  冯蔚 《世界地震译丛》2011,(3)

分辨多数余震和后续主震是由静态应力触发(Stein,1999;Todaetal,2005;Parsons,2002)还是动态应力触发(Hilletal,1993;kilb,2003;Brodsky and Prejean,2005;Gomberg and Johnson,2005;Hill and Prejean,2007),对理解地震内在作用和预测地震危险性是有必要的(Freed,2005)。Felzer和Brodsky(2006)分析了2≤M<3和3≤M<4级主震后5min内余震的空间分布情况,发现距主震50km范围内M≥2余震具有特定的幂律衰减关系,且衰减曲线的斜率为-1.35。据此,他们认为余震随距离的衰减只能用动态触发来解释。基于上述假设我们进行了一系列的检验,但没有一个可通过检验,进而,本文中对这种衰减关系提出了另外一种解释。在距离2≤M<3主震300m以外的地方,主震前5min内的地震活动性衰减与主震后5min内的衰减没有显著的区别,表明主震对它静态触发区域以外的地方没有影响。表征余震基本特性的大森随时间衰减关系在距离主震10km以外的地方是不存在的。最后,发现在主震波前未到达之前的余震中发现了...  相似文献   

Climate-driven shifts in diatom assemblages recorded in annually laminated sediments of Sacrower See (NE Germany)   总被引：1，自引：1，他引：0  

E. P. Kirilova  O. Heiri  P. Bluszcz  B. Zolitschka  A. F. Lotter 《Aquatic Sciences - Research Across Boundaries》2011,73(2):201-210

Sacrower See is a eutrophic lake with annually laminated sediments extending back to A.D. 1868. Analysis of annual layers revealed multi-decadal periods of distinct diatom assemblages at A.D. 1868–1875, 1876–1940, 1941–1978, and 1979–2000. Detrended correspondence analysis performed on individual seasonal sediment layers showed decadal-scale patterns of turnover in the diatom flora. The spring–summer layers showed higher sample scores until the early 1960s, after which the differences with the autumn–winter layers became smaller. Rates-of-change analysis revealed that the seasonal variability in diatom assemblages was higher than the annual changes. Summer diatom rates of change over the period A.D. 1894–1960 was on average higher than for winter, whereas between the 1960s and 1970s the winter rates of change became higher than the summer ones. Redundancy Analyses showed that seasonal temperatures and wind strength were significant explanatory variables for diatom assemblages in both annual and seasonal layers. These results suggest that meteorological changes indirectly affected diatom assemblages via the mixing regime of the lake. A comparison of the diatom rates of change with the amplitude of inter-annual climate change shows a statistically significant correlation for the spring-summer layers in the period of A.D. 1963–2000, showing that the sensitivity of diatom assemblages to meteorological changes has varied over the past century, with a stronger effect on diatoms registered during the past 40 years.  相似文献   

“Dead Zone” dynamics in Lake Erie: the importance of weather and sampling intensity for calculated hypolimnetic oxygen depletion rates     

Joseph D. Conroy  Leon Boegman  Hongyan Zhang  William J. Edwards  David A. Culver 《Aquatic Sciences - Research Across Boundaries》2011,73(2):289-304

Calculated hypolimnetic oxygen depletion (HOD) rates depend not only on environmental factors but also logistical ones. In particular, lack of understanding of the effects of weather in addition to how sampling effort determines calculated HOD rates complicates ecological understanding and environmental management of lake ecosystems. To better determine the roles of weather and sampling effort, we combined (1) weekly measurements of temperature and dissolved oxygen (DO) concentrations from seven stations in the Sandusky subbasin of Lake Erie’s central basin during 2005, (2) contemporaneous measures of storm activity and tributary discharge, and (3) a two-dimensional coupled hydrodynamic, chemical, and biological model of Lake Erie to investigate (1) how increased storm activity and tributary discharge affected short- (daily) and long-term (seasonal) dynamics of hypolimnetic hypoxia, and (2) how spatial (number of sites sampled) and temporal (sampling frequency) sampling effort affected calculated HOD rates. Our model closely replicated field-observed DO dynamics. When comparing baseline modeled dynamics to those in a second simulation with twice the number of days with high winds, however, we found that with more storm activity (1) periods of entrainment became more frequent, (2) the hypolimnion was warmer, (3) thermal stratification occurred 1 month later, whereas autumnal turnover occurred at least 1 week earlier shortening the duration of stratification by 1–2 months, and (4) HOD rates increased 12%. Further, spatial and temporal sampling intensity also affected calculated HOD rates. Consequently, adequately quantifying actual HOD rates requires sufficient sampling effort and the particular role of weather should be assessed with rigorous field and simulation studies, especially if HOD rates are used to indicate management success.  相似文献   

Hydropeaking indicators for characterization of the Upper-Rhone River in Switzerland   总被引：1，自引：0，他引：1  

T. Meile  J.-L. Boillat  A. J. Schleiss 《Aquatic Sciences - Research Across Boundaries》2011,73(1):171-182

River channelization and the construction of high-head storage schemes have been the basis of agricultural and socio-economic development in many alpine regions. One example is the Upper-Rhone River in Switzerland. The Upper-Rhone’s morphology changed considerably between 1863 and 1960 as a result of two major channelizations and, from 1950 on, the construction of a large number of high-head storage hydropower schemes in the catchment. These modifications have brought large benefits to the local population, at the cost, however, of substantial disturbances in aquatic and terrestrial ecosystems in and along the river. A primary factor behind these disturbances is the alteration of the natural flow regime, namely hydropeaking due to the operation of the high-head storage hydropower plants. For sustainable river-restoration projects on regulated rivers, scientists and engineers now widely accept the necessity of integrated management of the river. Different aspects such as river morphology, sediment management, water quality, temperature, and the naturally variable flow regime should be considered simultaneously. Mitigation of non-natural, sub-daily flow fluctuations due to hydropeaking is a crucial step in restoring natural flow regimes, but is especially challenging due to the economic constraints such mitigation places upon hydropower plants. With the goal of addressing this challenge, this paper proposes three indicators to describe the flow regime of rivers in alpine catchments with and without high-head storage hydropower plants. The indicators quantify: (1) the seasonal distribution and transfer of water, (2) sub-daily flow fluctuations, and (3) the intensity and frequency of flow changes. Indicators are evaluated in a case study of the Upper-Rhone River for pre- and post-impact situations, and the benefit of a multipurpose project reducing hydropeaking on hydrologic conditions is quantified. Furthermore, the paper explores the possibility of using these indicators to link aquatic and terrestrial ecosystem well being to their hydrology.  相似文献   

Erratum: Oxidation and emission of methane in a monomictic lake (Rotsee,Switzerland)     

C. J. Schubert  F. S. Lucas  E. Durisch-Kaiser  R. Stierli  T. Diem  O. Scheidegger  F. Vazquez  B. Müller 《Aquatic Sciences - Research Across Boundaries》2011,73(1):183-183

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