Relaxation on the Ismetpasa segment of the North Anatolian Fault after the Golcuk <i>M</i><sub>w</sub> = 7.4 and Duzce <i>M</i><sub>w</sub> = 7.2 shocks

The Ismetpasa segment of the North Anatolian Fault (NAF) is a rare place where aseismic fault slip (creep) has been observed. Its creep behaviour has been monitored using different observation methods since the 1950s. The findings obtained from the studies until 1990s showed that the creep rate exponentially decreased before the major shocks in 1999, Golcuk (Mw = 7.4) and Duzce (Mw = 7.2). After these shocks, three GPS periods observation in 2002, 2007 and 2008 were carried out on the geodetic network established around the segment. The evaluations of these observations showed that the creep behaviour relaxed after the major earthquakes. This result demonstrates that the creep behaviour of the Ismetpasa segment might be a warning before future major earthquakes

Monitoring subsidence effects in the urban area of Zonguldak Hardcoal Basin of Turkey by InSAR-GIS integration

Zonguldak Hardcoal Basin is the largest bituminous coal region in Turkey where extensive underground mining activity exists. Because of this activity subsidence effects have been experienced in different locations of the city. In this study, surface deformations caused by the subsidence have been observed by D-InSAR technique using C-Band RADARSAT data. InSAR data process of 16 RADARSAT images acquired between 24 July 2005–23 October 2006 has resulted in significant deformations in the order of about 6 cm in the most populated region of the city. The deformation map obtained has been integrated with digitized mine production maps and Quickbird Orthoimage into GIS. According to GIS analysis, there are three mine seams at different levels driven below the deformed zone. Many governmental and private buildings located in this area have a high potential risk of subsidence damage. Also, this area covers approximately 12 km of transportation routes

Determination of the 30-year creep trend on the Ismetpasa segment of the North Anatolian Fault using an old geodetic network

WOS: 000241015400003The Ismetpasa segment of the North Anatolian Fault was ruptured during both the 1944 (Mw = 7.2) Gerede and 1951 (Mw = 6.9) Kursunlu earthquakes. The field studies carried out in the aftermath of these two major earthquakes showed that the Ismetpasa segment had experienced a creep movement. To monitor the surface creep, a geodetic network with six control points was established on the segment. This network was observed three times-in 1972, 1982 and 1992. Based on our evaluations of those observations, the creep on the segment was geodetically determined to be 1.02 cm/year (1972-1982) and 0.93 cm/year (1982-1992) respectively. In 1999, the North Anatolian Fault experienced two major shocks-the Mw = 7.4 Golcuk and Mw = 7.2 Duzce earthquakes-both on the western part of the Ismetpasa fault. Using the global positioning system, our surveying team observed the network one more time in 2002 to assess whether these earthquakes affected the creep of the Ismetpasa segment, or not. The evaluation of the observations revealed a creep of 0.78 cm/year for the period 1992-2002. This result reveals that the creep of the segment has decreased in a linear fashion between 1972 and 2002 and that it had not been triggered by the Golcuk and Duzce earthquakes

Performance of artificial neural networks on Kriging method in modeling local geoid [Desempenho das redes neurais artificiais sobre o método da Krigagem no modelamento do geóide local]

Transformation of ellipsoidal heights determined by satellite techniques into local leveling heights requires geoid heights at points of interest. However, the geoid heights at each point are not available. In order to determine them, the local geoid in the transformation area must be modeled or computed by an appropriate method, one way of doing it, is to use control points both of whose ellipsoidal and local leveling heights are available. In this study, performance of geoid by ANN compared to Kriging method in modeling local geoid was presented. Moreover, the transformation ability of the methods was investigated through a geodetic test network in Bursa Metropolitan Area of Turkey. The results suggest that the model by ANN exhibit better results than the one by Kriging Method

An integrated approach for the prediction of subsidence for coal mining basins

In this study, land subsidence caused by underground mining activities was investigated by means of a new subsidence prediction approach (ISP-Tech) which takes into account the most important parameters contributing subsidence development such as coal production methods, depth, mining sequence and other geomechanical characteristics of underground rock strata, etc. ISP-Tech can be applied to operating mines to keep land subsidence under control as well as virgin coal sites to predict surface subsidence prior to mining activities. In the method, geological information gathered from the geographic information system (GIS) and the mining information system (MIS) are utilised to obtain geological cross-sections which are used in finite element models for mesh building. Then, a number of two dimensional finite element modelling analyses are carried out to determine land subsidence occurring due to mining operations. Finally, land subsidence predicted from modelling studies is compared to the GPS and/or differential interferometry synthetic aperture radar (DIn-SAR) measurements. If incompatibility of the results is detected, finite element meshes should be optimised, and then reanalysed to obtain more compatible results. In the study, two different case studies were given as examples of the application of ISP-Tech. Results of the case studies showed that ISP-Tech can successfully be applied to complex mine subsidence problems. The proposed approach gives more accurate results than those obtained from other classical subsidence prediction methods. © 2013 Elsevier B.V

Effects of errors in coordinates on transformation parameters

In the stage of transformation of global positioning system coordinates to a national coordinate system, the transformation parameters computed show local changes depending upon the selection of common points used in the transformation. The coordinates of the common points in both coordinate frames, however, contain various errors, which result in the local changes mentioned above. In this context, finding out the effects of possible errors in the coordinate components on the transformation parameters and determining which coordinate component influences which transformation parameter will help in developing alternate transformation strategies that can reduce the local effects. For this purpose, first the differential relations between the coordinates and transformation parameters are investigated on the basis of the three-dimensional similarity transformation, and then the degree of influencing-in other words, the effect order-is determined by investigating the relationship between parameter and geographic coordinate component. In this study the height component has been found to be the most affected component among the coordinates, which influences five out of seven transformation parameters

Integrating GPS and SAR: Monitoring coal-field subsidence

Subsidence of the earth's surface caused by underground mining can be monitored using terrestrial land-survey methods. However, applying these is difficult in hilly terrain and densely forested or urbanised areas. Such difficulties can be overcome with a combination of spaceborne SAR and GPS. InSAR accuracy corresponds to GPS and lies, with 9mm variance, in less than 8% of SAR signal phase

A comparison of two well known models for 7-parameter transformation

The transformation between two geocentric coordinate systems is carried out by the seven-parameter similarity transformation comprising three translations, three rotations and one scale difference. A number of approaches are available to realise this. Nevertheless, the Bursa-Wolf and Molodensky-Badekas models are generally favored for their simplicity. Except for their translations and their rms values both models yield similar results. Choosing a model producing more realistic translations is, of course, of paramount interest to surveyors. In this study, investigation of the cause of differences between translations of both models and which of these models produces more precise results is taken into consideration. The outcome of this investigation showed that the mathematical model of the Bursa-Wolf as opposed to the Molodensky-Badekas causes high correlations between transformation parameters, so Molodensky-Badekas model determines the translations better than the former