Performance of the L’Aquila (central Italy) gas distribution network in the 2009 (\mathrm{{M}}_\mathrm{{w}} 6.3) earthquake

Despite the seismic vulnerability of gas systems and the significance of the direct and indirect consequences that loss functionality might have on large communities, the analysis of the earthquake performance and of post-earthquake management for this kind of distribution networks appears under-represented in the international literature, with respect to other lifeline systems. To contribute on this matter, the study presented comprises an investigation of the impact of L’Aquila 2009 earthquake ( $\text{ M }_\mathrm{w}$ 6.3) on the performance of the local medium- and low-pressure gas distribution networks. The assessment of the physical impact of the earthquake to the buried components of network, namely pipes, valves, and demand nodes, was carried out when processing post-earthquake repair activity reports. Repair data, along with geometrical and constructive features, were collected in a geographic information system linked to the digitized maps of the network, and compared with the interpolated map of recorded transient ground motion, measured in terms of peak ground velocity (i.e., a $Shakemap^\mathrm{TM}$ ). The impact of permanent ground deformation was also investigated and found to be limited in the study area. The resulting observed repair rates (number of repairs per km), presented for different pipeline materials, were compared with repair ratio fragility functions available in literature, showing relatively agreement especially to those for steel pipes, likely also because of the uncertainties in the estimations. Finally, the management of the L’Aquila gas system in the emergency phase and the resilience (functionality recover versus time) of the system was discussed.     

The Characteristic Analysis and Seismic Triggering Study of the M6.2 and M6.1 Dayao Earthquake Sequences in 2003

INTRODUCTIONTheM6·2 andM6·1 earthquakes occurred successivelyin Dayao,Yunnan Province on July 21and October 16 ,2003 and bothinduced human casualty and economic loss to some extent .Adequatehistorical information reveals that ,earthquakes bigger thanM6·0 in Yunnan are distributed mainlyalong some active tectonic faults and seismic belts . Dayao and Yao an are in the Dianzhong tectonicblock andthere are noapparentfaultsthere(Su Youjing,2004) .Seismic activitylevel inthisregioniswea…     

Examination of Historical Data of the 1125 Lanzhou M7.0 Earthquake and Analysis of Seismogenic Structure

Detailed examination of historical data of earthquakes and field investigations of loess landslide caused by the earthquake and tracing of active faults in Lanzhou area indicate that the Yijitanpu town,one of six towns of Jincheng city,was devastated by the 1125 Lanzhou earthquake.The citly is now located in the Vinylon Factory south of Hekou(River Mouth)in the Xigu distict of Lanzhou city.We delermined that the six old towns mentioned in historical records lie in an area stretching from the south of Xigu district to Hekou in Lanzhou.This is consistent with the distibution of loess landslides caused by the earthquake,the extension of Holocene active faults,and the distribution of traces of the seismic rupture zone.A comprehensive analysis shows that the seismogenic structure for the 1125 Lanzhou M7.0 earthquake should be the Xianshuigou fault segment at the western termination of the north-border active fault zone of the Maxianshan Mountains which are located in south of Lanzhou city with the distance of only 4km.     

The GIS and analysis of earthquake damage distribution of the 1303 Hongtong M=8 earthquake

Introduction The 1303 Hongtong earthquake is an important earthquake in the eastern China. There is a lot of information in historical documents about the earthquake and many traces destroyed by the earthquake in the southern Shanxi Province. Many scholars have studied the earthquake from dif-ferent aspects, but mainly limited the definitions of the isoseismal and three factors of the earth-quake. Owing to being limited by the analysis technique, many useful damage information of the earthqu…     

Relationship between faults and generation of inland shallow earthquakes:enlighten-ment of the M=7.2

Ｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎｆａｕｌｔｓａｎｄｇｅｎｅｒａｔｉｏｎｏｆｉｎｌａｎｄｓｈａｌｌｏｗｅａｒｔｈｑｕａｋｅｓ：ｅｎｌｉｇｈｔｅｎ－ｍｅｎｔｏｆｔｈｅＭ＝７．２ｓｏｕｔｈｅｒｎＨｙｏｇｏｐｒｅｆｅｃ－ｔｕｒｅｅａｒｔｈｑｕａｋｅＴＯ...     

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…     

New paleontological evidence on time determination of the east part of the Eastern Kunlun Mélange and its tectonic significance

The area studied is located in the middle ofQinghai Province, at the south end of Qaidam Basinand the eastern part of the Eastern Kunlun Mountainsin Dulan County, Haixi Prefecture and Madoi County,Golog Tibetan Autonomous Prefecture, Qinghai Prov-ince (fig. 1). The area is situated tectonically in theeast of the Eastern Kunlun Mountains at the junctionof the Eastern Kunlun Orogenic Belt with the WesternQingling which is also the junction of the QaidamPlate with the South China Plat…     

Revised determination of the paleointensity in the cretaceous from the collection of A.S. Bol’shakov and G.M. Solodovnikov

A large volume of data on the paleointensity H _an obtained by A.S. Bol’shakov and G.M. Solodovnikov is ignored in modern reconstructions because the authors did not indicate whether they used the check-point procedure for the detection of chemical alterations in rocks associated with determination of H _an. The paper presents new values of H _an determined by the Thellier-Coe method with the use of the checkpoint procedure from samples of the Armenian collection of Cretaceous rocks used in published studies of Bol’shakov and Solodovnikov. The new results are close to the published ones and point to a small value of the geomagnetic field in the Cretaceous, thereby corroborating Bol’shakov-Solodovnikov’s hypothesis on a low paleofield in the Mesozoic. Our study of samples of the collection studied confirms the reliability of Bol’shakov-Solodovnikov’s determinations of H _an.     

Changes in the patterns of inorganic nitrogen and TN/TP ratio and the associated mechanism of biological regulation in the shallow lakes of the middle and lower reaches of the Yangtze River

The changes of NH3-N, NO3-N, NO2-N and TN/TP were studied during growth and non-growth season in 33 subtropical shallow lakes in the middle and lower reaches of the Yangtze River. There were significant positive correlations among all nutrient concentrations, and the correlations were better in growth season than in non-growth season. When TP>0.1 mgL-1, NH3-N increased sharply in non-growth season with increasing TP, and NO3-N increased in growth season but decreased in non-growth season with TP. These might be attributed to lower dissolved oxygen and low temperature in non-growth season of the hypereutrophic lakes, since nitrification is more sensitive to dissolved oxygen and temperature than antinitrification. When 0.1 mgL-1>TP>0.035 mgL-1, TN and all kinds of inorganic nitrogen were lower in growth season than in non-growth season, and phytoplank-ton might be the vital regulating factor. When TP<0.035 mgL-1, inorganic nitrogen concentrations were relatively low and NH3-N, NO2-N had significant correlations with phytoplankton, indicating that NH3-N and NO2-N might be limiting factors to phytoplankton. In addition, TN/TP went down with decline in TP concentration, and TN and inorganic nitrogen concentrations were obviously lower in growth season than in non-growth season, suggesting that decreasing nitrogen (especially NH3-N and NO3-N) was an important reason for the decreasing TN/TP in growth season. The ranges of TN/TP were closely related to trophic level in both growth and non-growth seasons, and it is apparent that in the eutrophic and hypertrophic state the TN/TP ratio was obviously lower in growth season than in non-growth season. The changes of the TN/TP ratio were closely correlated with trophic levels, and both declines of TN in the water column and TP release from the sediment were important factors for the decline of the TN/TP ratio in growth season.     

Seismic characteristics near the epicenter of the 1303 Hongtong M=8 earthquake, Shanxi Province and its implication

Introduction A great earthquake occurred on Sept. 25 of 1303 (Seventh of Dade, Yuan Dynasty) around Zhaocheng and Hongtong in Shanxi Province. The great earthquake is a very famous one, which is affirmed as the first earthquake with magnitude 8 in Chinese history. The catastrophes took place; meanwhile, huge archives of the disaster were recorded. According to these disaster recordings, the first isoseismal map in China was delineated, which provide us with abundant information of intensi…     

Characteristics of Collapses Caused by the M 8.1 Earthquake West of the Kunlun Mountains Pass

An M 8.1 earthquake that occurred west of the Kunlun Mountains Pass has caused more than 20 collapse bodies or zones, which are mainly distributed near the surface seismic rupture zone, west of Hoh Sai Lake. The collapses are of four types, bedrock, soil mass and ice mass collapses and avalanches. The spatial distribution and the characteristics of development of the collapses are analyzed in the paper. Comparised with those caused by other earthquakes, the collapses are smaller in scale. In addition to the lithological characteristics of the crustal media, topographic, geomorphic and climatic factors, weaker seismic ground motion is an important cause for formation of the smaller-scale collapses. The long surface rupture zone and weaker ground motion are important features of the seismic rupture, which may be related to the structure of the preexisting fault.     

Seismic tomography and anisotropy in the source area of the 2008 Iwate–Miyagi earthquake (M 7.2)

In order to understand the generation mechanism of the Iwate–Miyagi earthquake (M 7.2) that occurred on 14 June 2008 in Northeast Japan, we determined high-resolution 3D seismic velocity (Vp, Vs) and Poisson's ratio (σ) structures as well as P-wave azimuthal anisotropy in and around the source area using 246,623 P-wave and 189,153 S-wave high-quality arrival times from 1941 aftershocks of the 2008 Iwate–Miyagi earthquake as well as 4878 shallow and intermediate-depth earthquakes in this area recorded by the dense High-Sensitivity Seismic Network (Hi-net) and the seismic stations of Tohoku University. Our results show that hypocenters of the mainshock and three large aftershocks are located in a boundary zone where both seismic velocity and Poisson's ratio change drastically in a short distance. A zone with pronounced low-velocity and high Poisson's ratio is revealed in the lower crust and uppermost mantle under the source area, which may reflect the arc magma and fluids ascending from the upper-mantle wedge. The P-wave azimuthal anisotropy is complex under the study area, which may also indicate the complex crustal structure there. These results indicate that the generation of the 2008 Iwate–Miyagi earthquake was influenced by the ascending arc magma and fluids associated with the dehydration reactions of the subducting Pacific slab under Northeast Japan.     

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

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

Focal Fault and Stress Field of the Yao‘ an M 6.5 Earthquake on January15,2001

Using the 78 focal mechanism solutions of the fore shocks, main shock and after shocks of the earthquake sequence for the Yao'an earthquake, the characteristics of the focal faults and stress field for the earthquake sequence are analyzed. The results show that the main rupture plane of the Yao'an earthquake sequence is a tectonic fault with N50°W strike and steep dip and all the main shock, the fore shocks and the vast majority of after shocks occurred on the main rupture plane. A tectonic fracture with NNE-NE strike also participated in development process of the sequence. The focal stress field of the sequence dominated by principal compressional stress with nearly horizontal orientation SSE is consistent with the regional tectonic stress field. In the sequence development, the stress field in the focal region was complex with multi-azimuths and multi-action models and the focal rupture showed complex features with multi-directions and multi-patterns.     

Estimation of the stress levels in the focal region before and after the 2001 M=8.1 Western Kunlun Mountain Pass earth-quake

Introduction A great earthquake of M=8.1 occurred at 17h26min14.7s (Beijing time) on November 14, 2001 on the eastern Kunlun fault, near Bukadaban mountain peak with an elevation of about 6 866 m in the Qinghai-Xizang (Tibetan) Plateau of western China. The micro-epicenter is at a site of 36.2°N, 90.9°E, and the macro-epicenter is at a site of 35.6°N, 94.1° E, about 300 km west to the Kunlun Mountain Pass.This event is the largest one since 1951 in China, and yet the first su-per-st…