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Comparative tests of seismic sources and geophones aiming at shallow reflection seismic investigation in urban areas
Bhokonok, Oleg;Prado, Renato Luiz;Diogo, Liliana Alcazar;
Revista Brasileira de Geofísica , 2006, DOI: 10.1590/S0102-261X2006000100006
Abstract: pseudo walkaway noise tests were accomplished in study area in s？o paulo city, brazil, in order to evaluate the potentiality of seismic reflection technique in shallow geological/geotechnical investigation in urban environment, where there is usually the presence of different types as well as intensities of noises and the paved surface. data acquisition was conducted with a 24 channel seismograph with 24 bit a/d converter, 28 hz and 100 hz geophones, as well as sledge hammer and seismic rifle as sources. the best results were obtained with: (i) 100 hz geophones with 0.18 m spike and hammer source with steel plate; (ii) 100 hz geophones coupled through clay on asphaltic coverage with hammer source applied on asphalt. laboratory tests were also accomplished in shake table in order to evaluate geophone responses when they were coupled with different types of clay. tests indicated clay employment is a good alternative to couple geophones, notwithstanding kaolinitic clays are less indicated.
Analysis of seismic noise to check the mechanical isolation of a medical device
Paola Cusano,Antonella Bobbio,Gaetano Festa,Simona Petrosino
Annals of Geophysics , 2011, DOI: 10.4401/ag-4774
Abstract: We have investigated the mechanical response of a magnetically shielded room that hosts a magnetoencephalography system that is subject to external vibrations. This is a superconducting quantum interference device, which are the most sensitive sensors for magnetic flux variations. When the magnetoencephalography operates with people inside the room, the spectrum of the flux of the magnetic field shows anomalous peaks at several frequencies between 1 Hz and 20 Hz, independent of the experiment that is being run. As the variations in the flux of the magnetic field through the sensors might not only be related to the electrical currents circulating inside the brain, but also to non-damped mechanical oscillations of the room, we installed seismic instrumentation to measure the effective motion inside the room and to compare it to the external motion. For this analysis, we recorded the ambient seismic noise at two very close stations, one inside the magnetically shielded room, the other one outside in the room in which the magnetically shielded room is itself located. Data were collected over four days, including a week-end, to study the response of the magnetically shielded room subjected to different energy levels of external vibrations. The root mean square, Fourier spectra and power spectral density show significant differences between the signal recorded inside and outside the magnetically shielded room, with several anomalous peaks in the frequency band of 1 Hz to 20 Hz. The normalized spectral quantities (horizontal to vertical spectral ratio, and ratio between the internal and external spectra) show large amplification at several frequencies, reaching in some cases one order of magnitude. We concluded that the magnetically shielded room does not dampen the external vibrations, but it instead appears to amplify these across a broad frequency range.
The historical earthquakes of Syria: an analysis of large and moderate earthquakes from 1365 B.C. to 1900 A.D.
M. R. Sbeinati,R. Darawcheh,M. Mouty
Annals of Geophysics , 2005, DOI: 10.4401/ag-3206
Abstract: The historical sources of large and moderate earthquakes, earthquake catalogues and monographs exist in many depositories in Syria and European centers. They have been studied, and the detailed review and analysis resulted in a catalogue with 181 historical earthquakes from 1365 B.C. to 1900 A.D. Numerous original documents in Arabic, Latin, Byzantine and Assyrian allowed us to identify seismic events not mentioned in previous works. In particular, detailed descriptions of damage in Arabic sources provided quantitative information necessary to re-evaluate past seismic events. These large earthquakes (I0>VIII) caused considerable damage in cities, towns and villages located along the northern section of the Dead Sea fault system. Fewer large events also occurred along the Palmyra, Ar-Rassafeh and the Euphrates faults in Eastern Syria. Descriptions in original sources document foreshocks, aftershocks, fault ruptures, liquefaction, landslides, tsunamis, fires and other damages. We present here an updated historical catalogue of 181 historical earthquakes distributed in 4 categories regarding the originality and other considerations, we also present a table of the parametric catalogue of 36 historical earthquakes (table I) and a table of the complete list of all historical earthquakes (181 events) with the affected locality names and parameters of information quality and completeness (table II) using methods already applied in other regions (Italy, England, Iran, Russia) with a completeness test using EMS-92. This test suggests that the catalogue is relatively complete for magnitudes >6.5. This catalogue may contribute to a comprehensive and unified parametric earthquake catalogue and to a realistic assessment of seismic hazards in Syria and surrounding regions.
induced by trains: a new seismic source and relative test
可作为新震源的列车振动及实验研究
LI Li PENG Wen-Tao LI Gang CHEN Yong CHEN Qi-Fu TANG Yi Center for Analysis,Prediction,China Earthquake Administration,Beijing,China Institute of Geology,Geophysics,Chinese Academy of Sciences,Beijing,China Institute of Geophysics,China Earthquake Administration,Beijing,China,
李丽,彭文涛,李纲,陈,陈棋福,汤毅
地球物理学报 , 2004,
Abstract: 利用地震仪器对火车通过大同一秦岭铁路线产生的振动进行了观测．观测中使用了两套宽频带地震仪和一套短周期地震仪，共获得距铁路0～2．15km的9个观测点的38次列车振动观测数据，全部记录均可分辨出清晰的地震波形．研究表明：运动列车会在铁路沿线2～3km范围内产生明显的地面振动，接收到的振动频谱在0．05～20Hz范围内平坦，信号频带较宽，观测重复性好．列车振动为利用地震勘探方法探测地下浅层结构提供了一种重复性很好的新震源．
A Methodology for a Comprehensive Probabilistic Tsunami Hazard Assessment: Multiple Sources and Short-Term Interactions
Grezio Anita,Roberto Tonini,Laura Sandri,Simona Pierdominici,Jacopo Selva
Journal of Marine Science and Engineering , 2015, DOI: 10.3390/jmse3010023
Abstract: We propose a methodological approach for a comprehensive and total probabilistic tsunami hazard assessment ( TotPTHA), in which many different possible source types concur to the definition of the total tsunami hazard at given target sites. In a multi-hazard and multi-risk perspective, the approach allows us to consider all possible tsunamigenic sources (seismic events, slides, volcanic eruptions, asteroids, etc.). In this respect, we also formally introduce and discuss the treatment of interaction/cascade effects in the TotPTHA analysis and we demonstrate how the triggering events may induce significant temporary variations in short-term analysis of the tsunami hazard. In two target sites (the city of Naples and the island of Ischia in Italy) we prove the feasibility of the TotPTHA methodology in the multi—source case considering near submarine seismic sources and submarine mass failures in the study area. The TotPTHA indicated that the tsunami hazard increases significantly by considering both the potential submarine mass failures and the submarine seismic events. Finally, the importance of the source interactions is evaluated by applying a triggering seismic event that causes relevant changes in the short-term TotPTHA.
Clusters of Moderate Size Earthquakes along Main Central Thrust (MCT) in Himalaya  [PDF]
Basab Mukhopadhyay
International Journal of Geosciences (IJG) , 2011, DOI: 10.4236/ijg.2011.23034
Abstract: The Main Central Thrust (MCT) in Himalaya is seismically active in segments. In recent times, strain release within these active segments produce five spatial clusters (A to E; Figure 1). The seismicity within the cluster zones occurs in two depth bands; corresponding to the base of upper and lower crust. Depth sections across the clusters illustrate gently dipping subducted Indian Plate, overriding Tibetan Plate and compressed Sedimentary Wedge in between, with mid crustal ramping of MCT. Several presumptions / hypotheses have been put forward to decipher the causes of clustering along MCT. These are segmental activation of MCT, cross fault interactions, zones of arc parallel and arc perpendicular compressions, pore pressure perturbations, low heat flow zones etc. But these hypotheses need to be evaluated in the future after more ground level data are available. The maximum size of seismic threat that MCT can produce is inferred to be around Mw 7.0 in those clusters.
Large volume air-gun sources and its seismic waveform characters
大容量气枪震源及其波形特征
ZHAO Ming-Hui,QIU Xue-Lin,XIA Shao-Hong,WANG Ping,XU Hui-Long,YE Chun-Ming,KANG Ying,
赵明辉
地球物理学报 , 2008,
Abstract: 大容量低频组合气枪震源已成功应用于南海北部海陆联测实验及陆上水库实验,其信号传播最远距离可达255 km.为了探讨气枪信号的波形特征,从广东省地震台网数据中选择了台基相同、震级与震中距相近的珠海台的地震记录,将气枪震源、天然地震和爆破三种震源的波形特征进行了对比分析,结果表明.气枪信号特征明显,信号主频4～8 Hz,振幅±0.15 μm穝-1,波形一般具有3～5个峰值,并随时间有规律变化,易于准确识别.实验探测结果说明,这种能量强、重复性好、探测精度高、绿色环保的枪阵组合震源可广泛应用于海洋与陆地深部结构研究.
An Explorative Study on Major Stressors and Its Connection to Depression and Chronic Stress among German Elite Athletes  [PDF]
Insa Nixdorf, Raphael Frank, Jürgen Beckmann
Advances in Physical Education (APE) , 2015, DOI: 10.4236/ape.2015.54030
Abstract: Although research shows that chronic stress and specific stressful events (e.g. injury, failure) are associated with depressive symptoms in athletes, connections between chronic, major stressors and depressive symptoms are yet unknown. Therefore, the goal of the study was to gain new findings between major stressors and their relations to depressive symptoms and chronic stress. A total of 134 elite athletes provided data in an online survey. In addition to quantitative measurements (current depressive symptoms, and level of chronic stress), possible stressors were assessed qualitatively with an open ended question. By using content analysis to explore stressors, three different types of stressors were categorized: Double burden, sport specific demands, and conditions. Further statistical analysis found these stressors to be associated with dropout intentions, depression and chronic stress. Athletes, who reported sport specific demands (such as high training loads) as major stressors indicated higher levels of chronic stress and depressive symptoms than athletes without major stressors. Further research investigating sources of stress and its association to depressive syndromes in athletes could benefit from considering sport specific factors.
Assessment of Groundwater Quality in Central India  [PDF]
Shabya Choudhary, Shobhana Ramteke, Keshaw Prakash Rajhans, Pravin Kumar Sahu, Suryakant Chakradhari, Khageshwar Singh Patel, Laurent Matini
Journal of Water Resource and Protection (JWARP) , 2016, DOI: 10.4236/jwarp.2016.81002
Abstract: The groundwater is widely used for irrigation of rice crops. The overuse of groundwater causes depletion of the water quality (i.e. enormous increase in conductivity, hardness and ion and metal contents, etc.) in several regions of the country and world. In this work, the quality of the groundwater in the densestrice cropping area, Saraipali, Chhattisgarh, Central India is discussed. The water is sodic in nature with extremely high electrical conductivity. The mean concentration (n = 30) of F-, Cl-, NO3-, SO42-, NH4+, Na+, K+, Mg2+, Ca2+ and Fe in the water was 1.2 ± 0.2, 98 ± 31, 46 ± 15, 56 ± 9, 19 ± 4, 206 ± 25, 9.2 ± 2.3, 39 ± 6, 114 ± 19 and 1.7 ± 0.6 mg/L, respectively. The sources of the contaminants are apportioned by using the factor analysis model. The suitability of the groundwater for the drinking and irrigation purposes is assessed.
Collapses and seismic collapses in archaeology: proposal for a thematic atlas
E. Guidoboni,S. Santoro Bianchi
Annals of Geophysics , 1995, DOI: 10.4401/ag-4102
Abstract: The problem of how to recognise seismic collapse lies at the basis of the possibility of using archaeological sources in the rield of historical seismology. Hitherto this problem has been approached in an arbitraiy and subjectile manner, because there exists no systematic collection of data which permits access to a specific series of case histories in the field of archaeological collapse, distinguishing their numerous causes. The problein is also posed because archaeological techniques are by nature ~destructivena, nd important seismic traces may disappear and no longer be utilizable in the scientific sphere. The authors point our this documentary lacuna, and propose the compilation oT a thematic atlas on seismic collapses in archaeology: a new disciplinary tool. which may also prove useful for those concerned with the protection and conservation of archaeological areas
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