Simulation of the active and quiet periods of seismicity

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The interdisciplinary role of space geodesy—Revisited

In 1988 the interdisciplinary role of space geodesy has been discussed by a prominent group of leaders in the fields of geodesy and geophysics at an international workshop in Erice (Mueller and Zerbini, 1989). The workshop may be viewed as the starting point of a new era of geodesy as a discipline of Earth sciences. Since then enormous progress has been made in geodesy in terms of satellite and sensor systems, observation techniques, data processing, modelling and interpretation. The establishment of a Global Geodetic Observing System (GGOS) which is currently underway is a milestone in this respect. Wegener served as an important role model for the definition of GGOS. In turn, Wegener will benefit from becoming a regional entity of GGOS.What are the great challenges of the realisation of a 10^?9 global integrated observing system? Geodesy is potentially able to provide – in the narrow sense of the words – “metric and weight” to global studies of geo-processes. It certainly can meet this expectation if a number of fundamental challenges, related to issues such as the international embedding of GGOS, the realisation of further satellite missions and some open scientific questions can be solved. Geodesy is measurement driven. This is an important asset when trying to study the Earth as a system. However its guideline must be: “What are the right and most important observables to deal with the open scientific questions?”.     

Primary component analysis method and reduction of seismicity parameters

Introduction Data mining (SHAO and YU, 2003) is a new kind of technique developed with database and artificial intelligence in recent years, which processes the data in the database to abstract the im- plied and pre-unknown, but potentially useful information and knowledge from large amounts of incomplete, noisy, blurring and stochastic data. For data mining, data purging is an important link beforehand that includes eliminating noise, making up lost domain, and deleting ineffective data, as…     

Prediction of maximum magnitude and original time of reservoir induced seismicity

Introduction Prediction of RIS includes earlier stage prediction and seismic tendency prediction. In earlier stage, the prediction is to predict the possibility and maximum magnitude of RIS before reservoir are built up. It is made up on the basis of geological condition and the definite method and the statistical model method are usually used. The definite method by analogy with geological condi-tion is to analyze and sum up the main conditions of RIS. Using the main conditions compared w…     

Detection capabilities of the BURAR seismic array—contributions to the monitoring of regional and distant seismicity

Data recorded with the Bucovina Romanian Seismic Array (BURAR) seismic array between January 2005 and December 2008 were analyzed to verify the monitoring capabilities of regional and distant seismicity. For this time interval, nearly 35,000 events detected by BURAR and identified in seismic bulletins (Preliminary Determination of Epicenters and Romanian Earthquake Catalogue) were investigated using parameters as backazimuth, epicentral distance and magnitude. A remarkably detection capability is emphasized for teleseismic observations (Δ > 20°). BURAR onsets could be associated to almost 60% of all events in the teleseismic distance, with a magnitude detection threshold of 4.5 (mb). When no threshold magnitude is applied, the full detection capability of BURAR is in the same order as the performance of GERES array, which is one of the most sensitive stations in Central Europe. For regional events, detection capability decreases to about 16% of all events within regional distance range. The site conditions (crustal structure and high frequency cultural noise) as well as array dimension, affect the signal coherency and reduce the array detection capability for regional events. For both teleseismic and regional distances, a monthly variation of BURAR detection capabilities has been found; the number of events detected during the summer time is diminished by the specific seasonal human activity and atmospheric conditions (thunderstorms). To prove the good detection capability of the BURAR for teleseismic distances, a comparison with the observations of the Romanian Real Time Network in terms of magnitude and epicentral distance was carried out. The higher signal detection capability of BURAR is due to the array techniques applied in data processing, which enhance the signal-to-noise ratio. The monitoring performed by the BURAR seismic array provides a good azimuthal coverage of the regional and distant seismicity, in a large range of epicentral distances.     

Role of reservoirs in sustained seismicity of Koyna-Warna region—a statistical analysis

Koyna-Warna region in western India is a globally recognized site of reservoir-triggered seismicity near the Koyna and Warna reservoirs. The region has been reported with several M?>?5 earthquakes in the last five decades including M6.3 Koyna earthquake which is considered as the largest triggered earthquake worldwide. In the present study, a detailed statistical analysis has been done for long period earthquake catalogues during 1968–2004 of MERI and 2005–2012 of CSIR-NGRI to find out the spatio-temporal influence of the Koyna and Warna reservoirs impoundment on the seismicity of the region. Depending upon the earthquake clusters, we divided the region into three different zones and performed power spectrum and singular spectrum analysis (SSA) on them. For the time period 1983–1995, the earthquake zone near the Warna reservoir; for 1996–2004, the earthquake zone near the Koyna reservoir; and for 2005–2012, the earthquake zone near the Warna reservoir found to be influenced by the annual water level variations in the reservoirs that confirm the continuous role of both the reservoirs in the seismicity of the Koyna-Warna region.     

Patterns of seismic sequences in the Levant—interpretation of historical seismicity

There are historical accounts of about a hundred damaging earthquakes that occurred during the last two millennia in the Levant, in and around the Dead Sea fault system, and about half of which were associated with additional felt shocks. Several modes of earthquake sequences can be distinguished in them: (a) In 46 accounts, only one single event is noted. These are not known from tectonic settings similar to that of the Levant, and may just be a result of incomplete reporting. (b) In four cases, quakes preceded the mainshock by minutes, hours, and up to several weeks—possibly foreshocks. (c) Thirty-five mainshock–aftershock sequences were noted, lasting hours, days, weeks, months, and even more than a year; four of these also have foreshocks. No typical delay time was recognized for the largest or most significant aftershocks: they appeared up to several months later. (d) Six of the reported mainshock–aftershock sequences appeared in a “storm.” Another 13 sequences are insufficient to specify further.     

Discussion 3 Physical and Numerical Modeling of Sedimentation

ThesessionstartedwithanexcelledkeynotepresentationbyB.C.YenfromtheUniversityofIllinoisatUrbana-Champaign,USA,thatprovidedahistoricalperspectiveonmodelingingeneralandapplicationtotheYellowRiver.HetracedthestartofmodernhydraulicmodelingtoLoutsJeromeFarquesofFrancewhobuiltaIif00scalemodeloftheGarvonnein1875.However,itwasGermanHydraulicengineersthatdevelopedhydraulicmodelsfortheYellowRiverstartingwithHerbertEngles(1854-1945),thenfollowedbyhisstudentOttoFranzius(1878-1936).ThestudiesinGe…     

Application of mechanical and statistical models to the study of seismicity of syn-thetic earthquake

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The seismicity of the Kamchatka region: 1962–2011

This paper reviews the Kamchatka seismicity for a 50-year period of observation. These data were used to carry out a regionalization of Kamchatka’s seismic volume and adjacent areas. In all, ten zones were identified with differing activities and origins of seismicity. A comparative analysis was carried out for the seismicity in the more active zones. We found significant differences between the structures of the southern and the northern segment in the Kamchatka part of the Kuril-Kamchatka subduction zone. Seismological data corroborated a relationship between the subduction zone and the underthrusting of the Pacific plate under the Eurasian plate. These data from the 50-year period of observation helped identify a new Koryak seismic belt that encompasses the northwestern coast of the Bering Sea. We provide a brief review of macroseismic effects due to the most significant earthquakes for the 1962–2010 period.     

Ottoman archives and the assessment of the seismicity of Greece 1456–1833

This article examines the contribution of Ottoman sources of historical information for the study of the seismicity of Greece, in particular of Athens during the period of the Ottoman domination, a period during which relatively few original Greek sources of data are available. An annotated list of a number of case histories of earthquakes in Greece from Ottoman sources is presented translating only a summary of the information for those who want to access the whole document. They contain not only a valuable record of earthquakes, but also, for the earthquake historian, a wealth of information about locations where earthquakes were not felt. The article discusses the effects of earthquakes, of the 1826–7 siege on the Acropolis its purpose being to provide information with such annotation as would facilitate its use by engineering seismologists with additional macroseismic data that could supplement the rather meagre information.     

Influence of seismicity parameter uncertainty on seismic hazard estimation of cities and towns

Introduction In his Doctor thesis, PAN (2000) has roughly studied some about the influence of parameter uncertainty on seismic hazard analysis. The aim of this paper is especially to study the uncertainty influence extent of seismic hazard analysis result in a spot, owing to the uncertainty of seismicity parameters induced by variational statistical time ranges of various statistical regions in the whole country. The authors have inquired into the uncertain extents of influence of seismic p…     

Sustainable development of India's waters—some policy issues

The paper develops a policy for the sustainable management of India's waters. It is demonstrated that, in contrast to the historical and current policy, a scientific policy could be developed, which will enable meeting the formidable challenges of the sustainable development of India's waters. An approach to policy formulation is also proposed. The institutional issues are briefly discussed. The article is based on a forthcoming book on the subject. A specific case is taken for reasons of realism to emphasize the possibility of creative policy formulation in other environments.     

The identification and criteria of short-term seismicity gap before a great earthquake

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What Does Control Earthquake Ruptures and Dynamic Faulting? A Review of Different Competing Mechanisms

The fault weakening occurring during an earthquake and the temporal evolution of the traction on a seismogenic fault depend on several physical mechanisms, potentially concurrent and interacting. Recent laboratory experiments and geological field observations of natural faults revealed the presence, and sometime the coexistence, of thermally activated processes (such as thermal pressurization of pore fluids, melting of gouge and rocks, material property changes, thermally-induced chemical environment evolution), elasto-dynamic lubrication, porosity and permeability evolution, gouge fragmentation and wear, etc. In this paper, by reviewing in a unifying sketch all possible chemico–physical mechanisms that can affect the traction evolution, we suggest how they can be incorporated in a realistic fault governing equation. We will also show that simplified theoretical models that idealistically neglect these phenomena appear to be inadequate to describe as realistically as possible the details of breakdown process (i.e., the stress release) and the consequent high frequency seismic wave radiation. Quantitative estimates show that in most cases the incorporation of such nonlinear phenomena has significant, often dramatic, effects on the fault weakening and on the dynamic rupture propagation. The range of variability of the value of some parameters, the uncertainties in the relative weight of the various competing mechanisms, and the difference in their characteristic length and time scales sometime indicate that the formulation of a realistic governing law still requires joint efforts from theoretical models, laboratory experiments and field observations.