Identifying the precursors of large (M ≥ 6.0) earthquakes in Kamchatka based on data from the Kamchatka Branch of the Russian expert council on earthquake prediction: 1998–2011

This paper describes the activities of the Kamchatka Branch of the Russian Expert Council on Earthquake Prediction, Assessment of Seismic Hazard and Risk (KB REC) over a 14 year period. We provide brief information on how the KB REC functions, the methods that are used for earthquake prediction in expert assessments, forecasts, and precursors of M ≥ 6.0 Kamchatka earthquakes for the 1998–2011 period. The efficiency of prediction using several methods is estimated.     

On the relationships of water-level variations in the E-1 well, Kamchatka to the 2008–2009 resumption of activity on Koryakskii volcano and to large (M ≥ 5) earthquakes

We discuss the water-level variations in the E-1 well for the time period between May 2006 and 2010, inclusive. A trend towards an increasing level at an abnormally high rate occurred from mid-2006 to December 2009. This increase is regarded as the response of the aquifer of gas-saturated ground water that exists in the volcanogenic-sedimentary deposits of the Avacha volcano-tectonic depression to volumetric compression strain changes during the precursory period and the occurrence of a swarm of small earthquakes $\left( {K_{S_{\max } } = 8.3} \right)$ in the area of Koryakskii Volcano and to its phreatic eruption. We estimated the volumetric compression as ??? = ?(4.1 × 10^?6?1.5 × 10^?5) from the amplitude of water-level rise using the elastic parameters of the water-saturated rocks. While the strain source was active, we observed a decreasing sensitivity of the hydrodynamic regime in the well to the precursory processes before large (M ?? 5.0) tectonic earthquakes.     

Deep structural characteristics and seismogenesis of the M≥8.0 earthquakes in North China

Introduction North China is a seismically active area in the eastern part of China, where four M8.0 earthquakes have been recorded in the historical documents and confirmed by the researchers. The first is the M=8.0 earthquake occurred in A.D. 1303 in Hongtong, Shanxi Province. It was the ear-liest M=8.0 earthquake recorded in the historical document in China. The second is the M=8.0 earthquake occurred in A.D. 1556 in Huaxian County, Shaanxi Province. The other two are the M=8.5 earth…     

Synchronization signals in the variations of groundwater chemical composition in Kamchatka in relation to the strong (M W ≥ 6.6) earthquakes

We consider the results of the statistical analysis using the methods of the principal components and canonical coherences applied to the processing of long (1986–2005) time series of hydrogeochemical observations at the flowing wells and springs in Kamchatka. The time-frequency diagrams of the evolution of informative statistics characterizing the collective behavior of multidimensional hydrogeochemical time series are constructed, and the time intervals and frequency bands where the synchronization signals (Lyubushin, 2007) appear are identified. The features of their occurrence are analyzed in comparison to the strong (M _w = 6.6?7.8) local earthquakes. It is found that such signals in the measurements of some multidimensional time series can arise both before and after earthquakes, i.e. these signals have a precursory (P2) and postseismic (P3) character.     

Deep structural characteristics and seismo—genesis of the M≥8.0 earthquakes in North China

Based on the results from seismogeological study,aeromagnetic inversion and deepseismic sounding(DSS),it is found that the M≥8.0 earthquakes in North China have three common deep structural characteristics,i.e,they all took place above the ultra-crustal deep faults or on the edges of the tectonic blocks with higher intensity,and there are low-velocity,low-density and high-conductive layers deep in the epicentral regions.The origins of the earth-quakes are also discussed and the two possibilities of seismogenesis are proposed,i.e,tectonic movement and intracrustal explosion.     

Source parameters of small and moderate earthquakes in the area of the 2009 L’Aquila earthquake sequence (central Italy)

The main goal of this study is to provide moment tensor solutions for small and moderate earthquakes of the 2009 L’Aquila seismic sequence (central Italy). The analysis was performed by using data coming from the permanent Italian seismic network run by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the “Cut And Paste” (CAP) method based on broadband waveform inversion. Focal mechanisms, source depths and moment magnitudes are determined through a grid search technique. By allowing time shifts between synthetics and observed data the CAP method reduces dependence of the solution on the assumed velocity model and on earthquake location. We computed seismic moment tensors for 312 earthquakes having local magnitude in the range between 2.7 and 5.9. The CAP method has made possible to considerably expand the database of focal mechanisms from waveform analysis in the lowest magnitude range (i.e. in the neighborhood of magnitude 3) without overlooking the reliability of results. The obtained focal mechanisms generally show NW–SE striking focal planes in agreement with mapped faults in the region. Comparisons with the already published solutions and with seismological and geological information available allowed us to proper interpret the moment tensor solutions in the frame of the seismic sequence evolution and also to furnish additional information about less energetic seismic phases. Focal data were inverted to obtain the seismogenic stress in the study area. Results are compatible with the major tectonic domain. We also obtained a relation between moment and local magnitude suitable for the area and for the available magnitude range.     

Kinematic features of the seismogenic fault of the Tangshan earthquake and the recurrence period of large earthquakes

ＫｉｎｅｍａｔｉｃｆｅａｔｕｒｅｓｏｆｔｈｅｓｅｉｓｍｏｇｅｎｉｃｆａｕｌｔｏｆｔｈｅＴａｎｇｓｈａｎｅａｒｔｈｑｕａｋｅａｎｄｔｈｅｒｅｃｕｒｒｅｎｃｅｐｅｒｉｏｄｏｆｌａｒｇｅｅａｒｔｈｑｕａｋｅｓＪＩＥＬＩＵ１）（刘洁）ＨＵＩ－ＺＨＥＮＳＯＮ...     

Recognition of possible locations of future M ≥ 6.0 earthquakes: The Mediterranean mountain belts

The goal of the present work is to identify high-seismicity (High) intersections of morphostructural lineaments within the Mediterranean mountain belts (the Alps, Apennines, Balkanides, Dinarides, and the Carpathians). The intersections of lineaments, with the lineaments being boundaries of crustal blocks, were determined by morphostructural zoning. The epicenters of M ≥ 6.0 earthquakes and the intersections were found to be related. We used the KORA-3 recognition algorithm to identify the High intersections, where M >- 6.0 earthquakes can occur, separately for each mountainous country. Most of the High intersections identified here are located on higher-rank lineaments that separate major crustal blocks. The High intersections typically involve contrasting neotectonic movements and an increased crustal fragmentation. The results of this study point to a high seismic potential for the regions studied: we have identified many High intersections where no large earthquakes have yet been recorded.     

Source characterization and spatio–temporal evolution of the metal pollution in the sediments of the Basque estuaries (Bay of Biscay)

According to Water Framework Directive requirements, Member States must identify and analyze effects derived from human pressures in aquatic systems. As different kind of pressures can impact water bodies at different scales, analyses of spatio-temporal evolution of water bodies becomes essential in order to understand ecosystem responses. In this investigation, an analysis of spatio-temporal evolution of sedimentary metal pollution (Cd, Cr, Cu, Hg, Ni, Pb, Zn) in 12 Basque estuaries (Bay of Biscay) is presented. Data collected in extensive sampling surveys is the basis for the GIS-based statistical approach used. The implementation of pollution abatement measures is reflected in a long-term decontamination process, mostly evident in estuaries with highest historical sediment pollution levels. Spatial evolution is determined by either naturally occurring or human driven processes. Such spatial processes are more obviously being reflected in estuaries with lower historical sediment pollution levels.     

Contemporary (1960–2012) Evolution of the Climate and Surface Mass Balance of the Greenland Ice Sheet

We assess the contemporary (1960–2012) surface mass balance (SMB) of the Greenland ice sheet (GrIS), its individual components and trends. We use output of the high-resolution (11 km) regional atmospheric climate model (RACMO2), evaluated with automatic weather stations and GRACE data. A persistent negative North Atlantic oscillation index over the last 6 years resulted in the summertime advection of relatively warm continental air toward the GrIS. Added to the enhanced radiative forcing by increased CO₂ levels, this has resulted in an increase in near-surface temperature of more than 2 K during 2007–2012 compared to 1960–1990. The associated decrease in albedo led to an extra absorption of shortwave radiation of ～6 Wm^?2 (11 %) in the summer months, which is the main driver of enhanced surface melting and runoff in recent years. From 1990 onward, we see a steady increase in meltwater runoff and an associated decrease in the SMB, accelerating after 2005, with the record low SMB year in 2010. Despite the fact that the GrIS was subject to the highest surface melt rates in 2012, relatively high accumulation rates prevented 2012 to set a record low SMB. In 2012, melt occurred relatively high on the ice sheet where melt water refreezes in the porous firn layer. Up to 2005, increased runoff was partly offset by increased accumulation rates. Since then, accumulation rates have decreased, resulting in low SMB values. Other causes of decreased SMB are the loss of firn pore space and decreasing refreezing rates in the higher ablation area. The GrIS has lost in total 1,800 ± 300 Gt of mass from surface processes alone since 1990 and about half of that in the last 6 years.     

S-Wave Velocities of the Lithosphere–Asthenosphere System in the Caribbean Region

An overview of the S-wave velocity (V _s) structural model of the Caribbean with a resolution of 2°?×?2° is presented. New tomographic maps of Rayleigh wave group velocity dispersion at periods ranging from 10 to 40?s were obtained as a result of the frequency time analysis of seismic signals of more than 400 ray-paths in the region. For each cell of 2°?×?2°, group velocity dispersion curves were determined and extended to 150?s by adding data from a larger scale tomographic study (Vdovin et al., Geophys. J. Int 136:324–340, 1999). Using, as independent a priori information, the available geological and geophysical data of the region, each dispersion curve has been inverted by the “hedgehog” non-linear procedure (Valyus, Determining seismic profiles from a set of observations (in Russian), Vychislitielnaya Seismologiya 4, 3–14. English translation: Computational Seismology (V.I. Keylis-Borok, ed.) 4:114–118, 1968), in order to compute a set of V _s versus depth models up to 300?km of depth. Because of the non-uniqueness of the solutions for each cell, a local smoothness optimization has been applied to the whole region in order to choose a three-dimensional model of V _s, satisfying this way the Occam's razor concept. Several known and some new main features of the Caribbean lithosphere and asthenosphere are shown on these models such as: the west directed subduction zone of the eastern Caribbean region with a clear mantle wedge between the Caribbean lithosphere and the subducted slab; the complex and asymmetric behavior of the crustal and lithospheric thickness in the Cayman ridge; the predominant oceanic crust in the region; the presence of continental type crust in Central America, and the South and North America plates; as well as the fact that the bottom of the upper asthenosphere gets shallower going from west to east.     

Source mechanism of strong aftershocks (M_s≥5.6) of the 2008/05/12 Wenchuan earthquake and the implication for seismotectonics

Dozens of >M5, hundreds of >M4, and much more >M3 aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic stations. After relocated with P arrival, the >M3 aftershocks show two trends of distribution, with most of the aftershocks located along the north-east strike consistent with Longmenshan fault system, yet there is a north-west trend around the epicenter. It seems that substantially more aftershocks occur in regions with crystalline bedro...     

On the reality of the 56-year cycle and the increased probability of large earthquakes for Petropavlovsk-Kamchatskii during the period 2008–2011 according to lunar cyclicity

A 56-year cyclicity in the occurrence of large Kamchatka earthquakes has been previously detected. This is another manifestation of the tendency for the timing of large Kamchatka earthquakes to be synchronized to the cycles related to the period T _o of rotation of the lunar nodes found by V.A. Shirokov in 1974. He identified cycles of 18.6 years = T _o and 6.2 years = T _o/3, while the period of the 56-year cycle is 3T _o. The genuineness of that phenomenon had to be revised in connection with the occurrence of a large (M _w = 7.8) earthquake in Kamchatka at the end of 1997, in violation of the 56-year cyclicity. It turned out that, even though the 56-year cycle has become less distinct after the 1997 event, the cyclicity itself has remained statistically significant. A byproduct is an updated forecast of earthquake hazard for Kamchatka. The update is necessary in view of the approaching hazardous period of 2008–2011. It is found that, assuming the validity of these empirical tendencies, the expected rate of large earthquakes off Kamchatka for the period of August 2008 to October 2011 will be four times as high as the long-term mean. We derive the first-ever estimate of future hazard in terms of felt intensity for specified soil conditions (the so-called average soil) at a specified site (the town of Petropavlovsk-Kamchatskii). For these soil conditions, the estimated probability of at least one shock of intensity VII or greater during the period specified above is equal to 0.39 ± 0.15. The expected rate of single events or sets of events with M _w ≥ 7.6 in Kamchatka during this period is 0.76 ± 0.25.     

The crustal fluid evolution and the causes of earthquakes(Ⅲ)

Ｔｈｅｃｒｕｓｔａｌｆｌｕｉｄｅｖｏｌｕｔｉｏｎａｎｄｔｈｅｃａｕｓｅｓｏｆｅａｒｔｈｑｕａｋｅｓ（Ⅲ）ＣＨＡＮＧ－ＦＡＮＧＸＵ（徐常芳）ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｌｏｇｙ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕ，Ｂｅｉｊｉｎｇ１０００...     

Catalogue of earthquakes (September-November, 1993)

Ｃａｔａｌｏｇｕｅ　ｏｆ　ｅａｒｔｈｑｕａｋｅｓ　（Ｓｅｐｔｅｍｂｅｒ－Ｎｏｖｅｍｂｅｒ，１９９３）（陈培善）Ｃａｔａｌｏｇｕｅｏｆｅａｒｔｈｑｕａｋｅｓ（Ｓｅｐｔｅｍｂｅｒ－Ｎｏｖｅｍｂｅｒ，１９９３）￥Ｐｅｉ－ＳｈａｎＣＨＥＮ（Ｉｎｓｔｉｔｕｔｅ...     

Catalogue of earthquakes (March-May,1995)

Ｃａｔａｌｏｇｕｅｏｆｅａｒｔｈｑｕａｋｅｓ（Ｍａｒｃｈ－Ｍａｙ，１９９５）Ｐｅｉ－ＳｈａｎＣＨＥＮ（陈培善）（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕ，Ｂｅｉｊｉｎｇ１０００８１，Ｃｈｉｎａ）Ｉｌ...     

Catalogue of earthquakes(June-August,1993)

Ｃａｔａｌｏｇｕｅｏｆｅａｒｔｈｑｕａｋｅｓ（Ｊｕｎｅ－Ａｕｇｕｓｔ，１９９３）Ｐｅｉ－ＳｈａｎＣＨＥＮ（陈培善）（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕ，Ｂｅｉｊｉｎｇ１０００８１，Ｃｈｉｎａ）...     

Catalogue of earthquakes(September-Novem-ber,1994)

Ｃａｔａｌｏｇｕｅｏｆｅａｒｔｈｑｕａｋｅｓ（Ｓｅｐｔｅｍｂｅｒ－Ｎｏｖｅｍｂｅｒ，１９９４）陈培善Ｐｅｉ－ＳｈａｎＣＨＥＮ（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕ，Ｂｅｉｊｉｎｇ１０００８１，Ｃ...