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Xu, Zhiguo (National Marine Environmental Forecasting Center, Ministry of Natural Resources. Beijing) | Wang, Zongchen (National Marine Environmental Forecasting Center, Ministry of Natural Resources. Beijing) | Shi, Jianyu (National Marine Environmental Forecasting Center, Ministry of Natural Resources. Beijing) | Li, Hongwei (National Marine Environmental Forecasting Center, Ministry of Natural Resources. Beijing)
ABSTRACT Multiple-point source solution of 2020 Samos Mw7.0 earthquake in Greek was inverted using iterative deconvolution method from near field seismic records. The retrieving results have revealed that Samos Mw7.0 earthquake consisted of at least two subevent with similar normal fault-typing, the smaller subevent corresponds to ~3 s rupture time close to mainshock epicenter, the larger one has its position approximately 25 km west of the original rupture point with 8 s later moment release. We inferred that Samos earthquake occurred on a normal fault along the nearly EW trending, and two subevents successively ruptured separated by ~5 s. Furthermore, numerical simulation of the tsunami generated by Samos normal faulting earthquake was conducted from the uniform slip source model, indicating the Samos earthquake occurred as subsidence of normal fault hanging wall, and led to a large sudden coseismic vertical deformation surrounding the focal region, thus displacing the overlying water and produced a small scale local tsunami. INTRODUCTION A massive Mw = 7.0 earthquake that occurred ~10 km to the north and offshore of Samos Island, Greece (37.897°N 26.784°E) On 30 October 2020 11:51 UTC, at a shallow depth of ~21 km. This earthquake caused extensive damage on its surrounding areas, resulted in the collapse of buildings, numerous fatalities, and missing people, at least ~117 people were killed by earthquake. Most notably, the mainshock also triggered a powerful local tsunami that flooded into the island of Samos Island, Greece and the Aegean coast of the Izmir region, Turkey, and caused severely damage to building and structure, one person killed by drowning. After the Samos mainshock, the researchers from various earthquake agencies have made great progresses in understand this earthquake. The analysis of the mainshock and aftershock sequence reveals that it occurred on a nearly EW striking dip-slip normal fault located off the northern shore of Samos Island (Onder-Cetin et al., 2020; Papadimitriou et al. 2020). The distance between the USGS's initial epicenter and GCMT's centroid location is ~19 km (Fig. 1), indicating the the seismogenic zone is not considered to be single point source, the main rupture slip is located to west of the epicenter. The two major slip patches derived from the regional finite fault modeling. Hence, we employed the multiple-point source modeling to explore the focal mechanism characteristics, and further unveiling the temporal and spatial characteristics of the rupture.
ABSTRACT: This paper presents part of the slope stability improvement program carried out at Kışladağ Gold Mine in Turkey. A slope stability project was initiated at the site recently to review the minor slope failures as well as the geotechnical and final wall design aspects in detail. Two minor slope failures occurred in December 2014 at the north-east section of the pit in spite of the high quality slope stability implementations at Kışladağ Mine. The work presented in this paper showed that changes to the blasting and geotechnical parameters are required at the north-east section of the pit. Geotechnical design changes were 10 m bench heights with 70° slope face angle at that specific area. Having implemented several geotechnical and blast design changes, the followings were observed in the pit: reduced crest loss, reduced number of minor slope failures and more visible half barrels in friable rock types. 1 INTRODUCTION Kışladağ Mine is the largest gold mine in Turkey. It is operated by Tüprag Metal Madencilik which is a subsidiary of Eldorado Gold Corporation. The mine site is located in southwest of Usak, west-central Turkey between major cities Ankara and Izmir (Fig. 1). To date, detailed geotechnical data collection and evaluation studies as well as stability assessments have been carried out at the Kışladağ Gold Mine. The onsite geotechnical studies involved the following studies and methods:data collection and evaluation (geotechnical drilling of boreholes, scan line and window mapping surveys, geotechnical logging from oriented cores, rock mass classification, geotechnical characterization of the slope forming materials, pit dewatering and slope depressurization studies etc.); slope movement monitoring (manual surveying of prisms, slope monitoring radars (Reutech Mining 2016), visual inspections and wireline extensometers); slope performance evaluations (monthly berm and bench inspections, preparation of rock failure reports and open pit hazard map); and slope stability analyses (the use of different methods to assess the stability of the benches, berms and overall slopes under different conditions). This paper summarizes the recent geotechnical works and assessments which were combined with the final wall blasting project carried out on-site.
Abstract The main structure of the Poligon station, which is situated on route of Ü çyol-Ü çkuyular line as part of Izmir subway development works consists of diaphragm wall. Under the diaphragm wall, a tunnel is planned for docking the train to the station. Several old buildings with 8–10 stories are located near by the station structure. Many of which are not suited to new earthquake legislation. Condition of bed of tunnel is an alternation of claystone and sandstone, which consist of very weak and very strong units. Therefore, fore-support design was realized in this highly complex work environment in order to save the construction equipment and re-excavate T2 tunnel without damaging the structure of the station, substructure and surrounding buildings. In general, design system proposed here includes classical support systems, chemical injection and micro-cement injection. In this study, field studies for cross-failure at Izmir Subway Poligon Station, measurements, assessments, excavation and support design, which are suggested to re-excavate T2 tunnel are explained in detail. 1 Introduction In the design of underground openings in soft ground, reinforcement such as shotcrete, rock bolts, concrete cementing, steel support, etc. Are specifically established after a certain delay that require short-to-medium term pre-stress and strain calculations. This also relates to the prediction of potential damage on the buildings in the influence area of subway tunnel excavations. During the development works of Izmir Metro Project, T2 tunnel collapsed on March 21, 2012 near Poligon Metro Station, which is located on the route of Ü çyol-Ü çkuyular line and a work machine was buried in the rubble. A project was carried out to re-excavate the T2 tunnel and save the work machine without damaging the infrastructure of the station building in this rather complex environment which exhibits diaphragm walls, old buildings etc.
Aksoy, C. Okay (Dukuz Eylul University, Department of Minig Engineering) | Onargan, Turgay (Dukuz Eylul University, Department of Minig Engineering) | Kucuk, Kerim (Dukuz Eylul University, Department of Minig Engineering) | Genis, Melih (Zonguldak Karaelmas University, Department of Mining Engineering) | Guney, Avni (Mugla University, Department of Mining Engineering)
ABSTRACT In order to finish urban shallow tunnels (driven by NATM) projects as scheduled shafts should be sunk at certain intervals to form new excavation faces. Entering the tunnel from nearby shafts in addition to the tunnel axis to create new excavation faces is time consuming and costly. For this reason, to form new excavation faces directly from the shafts sunk in tunnel axis seems more economical. However, the greatest problem in such a study appears to be the stability. The stress accumulations at tunnel-shaft intersection areas contain hazard from the aspect of stability. Although it is not likely to face serious stability problem in strong rock, this situation is potentially prone to reaching to dangerous levels especially in weak rocks. In this study the stability at the shaft sunk in the tunnel axis and the intersection points of Goztepe station as part of the 2nd stage of Izmir Metro, was analyzed by numerical modelling. The accuracy of the numerical modelling results was later verified comparing with the results of in-situ surveys and measurements. During the study, shaft-tunnel intersection areas have been consolidated by umbrella arch method. The main reason for this strengthening was the obvious difference in the sizes of the shaft and the tunnel i.e., shaft crossectional areas was smaller than that of tunnel. Therefore, stability of tunnel-shaft intersection area was designed accounting that the whole load of the shaft was too be carried by the tunnel support and the ground itself. 1.INTRODUCTION Formation of new excavation faces along the route of conventional inner city tunnels shortens the completion time scheduled for tunnel construction. This may be achieved by either sinking shafts aligned with the axis of the main tunnel at certain intervals or by intersecting the main tunnel via subsidiary tunnels under suitable topographic conditions. The former way is considered to be both time consuming and costly. Therefore, the most cost efficient way appears to be sinking shafts along the tunnel axis to the cutting face provided that ground conditions are satisfactory and adequate reinforcement system is employed. Certain reinforcement systems cannot be literally distinguished. Thus, pipe-arch reinforcement process should be separated from other systems. In this process, the main tunnel is systematically excavated under the protection of previously constructed pipe jacking. The pipe arch process is one of the safest and most efficient ways of constructing large diameter tunnels over short distances. It is likely to encounter various applications of Pipe Arch method in literature (Hoek, 2003; Kim et al. 2004, Miura, 2003; Gibbs et al. 2002). The pipes can be exercised on the ground by two different methods, being pre-drilling and case- drilling. Both methods process advantages and disadvantages (Volkmann, 2004). In this study, deformations were investigated at the intersection of shaft no.8, one of the eight service shafts sunk on the axis of main tunnel route, and 5.2 km. long main tunnel constructed as the second stage of Izmir Metro Project.
ABSTRACT It is accepted that crustal rocks lose their magnetisation at the Curie point temperature. At this temperature, ferrimagnetic rocks become paramagnetic. The bottom of magnetised crust determined from the spectral analysis of residual magnetic anomalies is generally interpreted as the level of the Curie point isotherm. An alternative approach to interpretation of magnetic anomalies in terms of body parameters has been achieved by characteristic curves. For this study, the prism model was used and the parameters of the body were determined by curve matching. The residual between the observed and calculated anomalies is minimised by adjusting the model parameters automatically. The Curie depth points can be obtained at bottom of the prism. For that reason several prism should be used to prepare the Curie-depth map. This method was applied to the total magnetic field data of Izmir Bay and the depths of the Curie points were determined to be about 7–10 kin. These results were compared with the gravity, seismic and the calculated heat flow values of costal geothermal bore holes and a very good relationship was observed between them. INTRODUCTION Regional Geothermal Possibility and Geological Structural Relations; Anatolian tectonics is directly responsible for existing geothermal fields in Turkey. According to the intersection hypothesis of Ercau (1988), hot regions are situated at junction points of faults or grabens which extend in NS, NNE - SSW and EW. Neogene faults trends in the Western Anatolian are generally W - E direction and there are several grabens which are bounded with E - W trending normal faults ($eng6r 1982). The area of Izmir Bay is at the conjuncture of the Midilli - Karabmun system produced by the N - S compression and the Gediz graben which is under the extensional regime (Figure 1).
ABSTRACT Regional development planning is a complex procedure that requires input from numerous sources and usually involves a "large group of people with different backgrounds and objectives. Physical planning, socioeconomic, technological and environmental considerations have to be integrated in the design and development project. While the political and socioeconomic and institutional aspects may often be of dominant importance, there still is considerable demand for timely and relevant technical and scientific information processing point of view, these problems share the same characteristics. Planers and decision makers, and increasingly the general public, need and demand information to put the problem into context, from monitoring data to applicable standards. This information needs to be provided in a format that is directly understandable and useful. Time is always important. In this paper, sea water climate, wind and weather analysis, temperature, sea water conditions, physical parameters and current are observed in the offshore areas in Çeşme Peninsula (Izmir/TURKEY) for pollution monitoring purposes. These parameters and their variations have been recorded by IMST Institute's research vessel RV/K.Piri Reis in the waters of Aegean Sea of Turkish Economic Zone. Physical parameters of sea water, relative velocities and mixing procedure in the Aegean Sea have been important subjects for scientific research since 1982. However, very restricted new information has recently appeared in oceanographic journals about this area. The paper describes some interesting results obtained from the analysis of accurate directional wave and current data for two years at five shallow water coastal stations over different basins of the, Aegean Sea. The data analysis include statistics of main wave and current parameters and characteristics of directional spectra of, extreme sea states which are very useful for design of maritime and naval structures. The seasonal and annual variability of the wave and current climates is also analyzed for its implications in the study of beach evolution and coastal zone management (CZM).
ABSTRACT: Extensive marine surveys were performed at Bosphorus-Marmara junction before laying the offshore part of the Hamidabad natural gas pipeline system. This paper introduces IMST's wave measurement programme which is a part of these studies, and explains the assessment of wave-related design parameters of the submarine pipeline crossing the Sea of Marmara. INTRODUCTION The present study is a part of a more comprehensive research carried out to assess the oceanographical design parameters of the submarine pipeline laying between Ambarli and Pendik in the Marmara-Bosphorus junction (hereinafter BMJ area), and crossing the Izmit Bay. This submarine pipeline belongs to Hamidabad natural gas pipeline system transporting the Siberian gas of former USSR to Ankara-Turkey (Fig. 1). The entire system in the Turkish territories involves 842 km of pipelines of which a part of 123.4 km-long is offshore. The main characteristics of the system and basic aspects of the design procedure are explained by Akin and Akten (1988). The objective of the study is the ·evaluation of the extreme dynamic loads to which the pipeline may be subjected, in order to assure on-bottom stability during laying and during its operating life. Since it has been found necessary to perform a meteo-oceanographical survey which includes measurement of currents, hydrological parameters, sea levels, waves and collection of meteorological data in order to assess the environmental design parameters for the submarine pipeline project, Institute of Marine Science & Technology, Izmir, Turkey (hereinafter IMST) was requested by BOTAS (Turkish National Pipeline Corporation) to undertake some survey, activities in cooperation with Snamprogetti-Italy. 105 The results of IMST's efforts for the determination of current pattern in the BMJ area have already been introduced by De Filippi, Iovenitti & Akyarh (1986), Arnoy & Akyarh (1990) and Akyarli & Arisoy (1993, 1994).
ABSTRACT: The Bosphorus is among the major components of the Mediterranean-Aegean-Dardanelies-Marmara-Bosphorus-Black Sea system through which exchange of water between the Mediterranean and Black Seas occurs. At Its southern entrance, a tube tunnel crossing of the Bosphorus has been designed, and the Institute of Marine Science and Technology of Dokuz Eylül University, Izmir, Turkey (IMST) has conducted comprehensive oceanographic measurement campaigns to assess the environ· mental impacts of this project (Arisoy and Akyarli, 1990). This paper summarizes the studies conducted in this respect to complement the authors recent paper on the hydrodynamic characteristics of the BMJ area, which comprises the Sea of Marmara and the Bosphorus junction (Akyarli and Arisoy, 1993) and outlines the contribution of the IMST's surveys to an understanding of the complex two-layer flow system in the Bosphorus with a particular emphasis in the blocking phenomenon, which corresponds to an exceptional case due to the stopping of the lower layer flow before reaching the Black Sea. INTRODUCTION The Bosphorus is the strait between the Black Sea and Sea of Marmara; it is nearly 31 km in length; its width varies between 0.7 and 3.5 km, and mean and maximum depths are 35 m and 110 m, respectively. Here, while the narrowest width occurs at about 12 km north of the southern end, two sills exist with 33-m water depth approximately 3 km north of the same end and with 60-m water depth located 4 km north of the northern end (Unliiata, oguz, Latif, and Ozsoy, 1990). While the surface area of the Black Sea IS 426.000 kmi together with the Sea of Azov, it holds 537.000 km3 of water. Average water depth is 1271 m in the Black Sea depression; it increases towards the south and reaches its maximum of 2245 m around the central portion.