Evidence for surface rupture associated with the Mw 6.3 L'Aquila earthquake sequence of April 2009 (central Italy)

An earthquake of Mw = 6.3 struck L'Aquila town (central Italy) on 6 April 2009 rupturing an ∼18-km-long SW-dipping normal fault. The aftershock area extended for a length of more than 35 km and included major aftershocks on 7 and 9 April and thousands of minor events. Surface faulting occurred along the SW-dipping Paganica fault with a continuous extent of ∼2.5 km. Ruptures consist of open cracks and vertical dislocations or warps (0.1m maximum throw) with an orientation of N130°–140°. Small triggered slip and shaking effects also took place along nearby synthetic and antithetic normal faults. The observed limited extent and small surface displacement of the Paganica ruptures with respect to the height of the fault scarps and vertical throws of palaeo-earthquakes along faults in the area put the faulting associated with the L'Aquila earthquake in perspective with respect to the maximum expected magnitude and the regional seismic hazard.     

Impacts by heavy-oil spill from the Russian tanker Nakhodka on intertidal ecosystems: recovery of animal community

The impact of a heavy-oil spill from the Nakhodka on an intertidal animal community, and the recovery process of animals from the damage were surveyed from the autumn of 1997 to the spring of 2001. The field study was carried out in the rocky coast of Imago-Ura Cove, located along the Sea of Japan, where clean-up operations for oil pollution had been conducted less intensely than in other polluted areas. We have examined individual number of each animal taxon by continuously placing a quadrat of 5 m width along the entire intertidal zone of the cove. A total of 76 invertebrate taxa including 57 species of mollusks, 10 species of crustaceans were observed during the survey. The number of taxa increased from 1998 to 1999 in areas where the initial oil pollution was intense. Total individual number of benthic animals continued to increase from 1998 to 2000 in the polluted areas. The impact of oil on benthic animals was different from species to species. Some species such as Cellana toreuma and Monodonta labio confusa increased rapidly after the oil spill, whereas other species such as Patelloida saccharina lanx and Septifer virgatus did not show any apparent temporal tendencies. Population size structure of P. saccharina lanx varied greatly among years, however that of M. labio confusa did not. For P. saccharina lanx, recruitment was unsuccessful in 1997, possibly due to the effect of oil pollution. These differences in responses to oil pollution among benthic animals are considered to be caused by the differences in habitat use, susceptibility to heavy-oil, life history and migration ability. The findings suggest that it took at least 2-3 years for the intertidal animal community to recover to its original level after the oil spill.     

葡西地区油气储层泥质与粘土含量的计算方法研究

泥质和粘土含量是储层评价中很关键的参数,但是其解释精度一直难有很大的提高。以大庆油田西部地区的储层为例,研究了提高解释精度的方法。首先对粒度和X衍射粘土分析数据的用途和质量检查方法进行讨论。对自然伽马、自然电位等多种方法计算泥质含量的效果进行了对比,筛选了适合本区的解释方法。在此基础上,进一步对砂岩、泥岩参数的选取方法进行了研究,提出了变砂岩参数和分层平均方法。应用结果表明,在研究的区域,采用本文论述的方法计算泥质含量和粘土含量,比以往的解释精度有了大幅度的提高。     

吉林油田红岗北地区低阻油层评价技术

吉林油田红岗北地区部分井区油层电阻率相对较低,对测井油、水层解释造成了困难。利用岩心、测井及试油资料,分析形成低阻油层的主要因素是束缚水含量高,另外地层水矿化度高、淡水泥浆侵入、富含导电矿物等也是造成低阻的原因。因此,利用核磁测井资料建立了束缚水饱和度模型,形成了低阻油层的解释方法及标准,在实际应用中见到了较好的效果。     

基于MO和ArcSDE的城镇地籍建库工具箱开发与应用

城镇地籍数据建库是一项系统性、工程性和技术性相结合的工作。为了高效地、高质 量地、高水平地完成测绘数据的交换处理、权属数据的录入和图属一致控制,开发并 应用一套城镇地籍建库工具集具有极其重要的意义。本文基于MO和ArcSDE设计并 开发了企业级的建库工具箱,集中了各个环节的工具,为北京市城镇地籍建库提供了 有力支持。     

REGRESSION ON MULTIVARIATE IMAGES:PRINCIPAL COMPONENT REGRESSION FOR MODELING,PREDICTION AND VISUAL DIAGNOSTIC TOOLS

Regression between two blocks(usually called‘dependent’or Y and‘independent’or X)of data is a veryimportant scientific and data-analytical tool.Regression on multivariate images is possible and constitutesa meaningful addition to existing univariate and multivariate techniques of image analysis.The regressioncan be used as a modeling tool or for prediction.The form of the regression equation chosen is dependentupon problem specification and information at hand.This paper describes the use of principal componentregression(PCR).Both model building and prediction are presented for continuous Y-variables.The finalgoal is to supply new image material that can be used for visual inspection on a screen.Also,visual toolsfor diagnosis of model and prediction are provided,often based on derived image material.Examplesof modeling and prediction are given for six channels in a seven-channel satellite image     

3-D upper crustal tomographic structure across the Vrancea seismic zone, Romania

The VRANCEA99 and VRANCEA2001 seismic refraction experiments are part of a multidisciplinary project to study the Eastern Carpathians in Romania. The objectives of these studies are intended to disclose a more detailed picture of the crustal and upper mantle structures above the seismically active Vrancea region. In this paper we provide additional constraints for the upper crustal structures of the area. The 1999 campaign consisted of a 320-km-long N–S profile and a 70-km-long E–W profile. The intersecting 2001 profile extended in E–W direction from the Hungarian border to the Black Sea. In order to enhance the model resolution, first arrival data from local crustal earthquakes were also included.This configuration allowed for the first time to derive a 3-D velocity model for the upper crust of the Romanian Carpathian Orogen, within a 115×235 km wide region, centred over the Vrancea seismic zone. The 3-D model reveals lateral velocity variations, which were not visible on the in-line interpretations. It allows us to distinguish between foreland platform areas, foreland basins and the Carpathian Orogen. Clear velocity differences between the foreland basins south and southeast of the Eastern Carpathians and the Focsani Basin further north indicate different pre-Miocene sedimentary compositions and geological evolutions of these foreland platforms. The involved Moesian and Scythian platforms are separated by the Trotus Fault system, which is observed as a velocity discontinuity. An upper crustal high-velocity zone, above the northern Vrancea seismic zone, could also be identified. This high-velocity zone is explained by a Middle Pliocene to Pleistocene E–W oriented out-of-sequence thrust of the crystalline basement, below the decollement of the flysch nappes.     

Structure of the crust and uppermost mantle beneath southern Finland revealed by analysis of local events registered by the SVEKALAPKO seismic array

In 1998–1999, a large-scale seismic array was deployed in Finland as a part of the EUROPROBE/SVEKALAPKO subproject, involving 14 European universities and research institutes. The objective of the project was to map the deep lithosphere structure and thickness beneath the Fennoscandian Shield by means of teleseismic events. In addition, about 580 local seismic events were registered during the data acquisition period. Among them, only eight local earthquakes were recorded, the rest being quarry blasts from mining sites in Russia, Finland, Estonia and Sweden. In this study, we present the analysis of the seismic wave field from the strongest local events registered by the majority of the stations of the SVEcofennian–KArelian–LAPland–KOla Transect (SVEKALAPKO) array with the aim of mapping the structure of the upper mantle beneath the array. For this purpose, we selected the events corresponding to a single source type and compared these recordings with those from wide-angle reflection and refraction experiments in the area to identify the regional phases. The record sections of selected events demonstrate strong reflections (PmP) from the Moho boundary. The refracted Pn phases can be seen as first arrivals at distances of about 200–400 km from the source. At offsets of about 400–800 km, phases reflected from inhomogeneities in the uppermost mantle (P1) and double reflections from the Moho boundary (PmPPmP) were recorded.Results from 2D forward ray trace modeling of reflected and refracted P-waves along four profile swathes from SVEKALAPKO stations demonstrate that the mantle reflections originate from two different groups of boundaries beneath the array: one group of phases arrive from subhorizontal and gently dipping reflectors below the Moho boundary at a depth of 70–90 km, while the other group are phases originating from a depth of 100 to 130 km. Based on the irregular character of the first group of reflections, their different spatial orientation and correlation with the Moho offsets, we interpret the boundaries of this group as relicts of ancient subduction and collision processes. The second group of reflections can be explained by a transition from mechanically strong to mechanically weak lithosphere.