DESIGN OF GEODETIC NETWORKS BASED ON OUTLIER IDENTIFICATION CRITERIA: AN EXAMPLE APPLIED TO THE LEVELING NETWORK

We present a numerical simulation method for designing geodetic networks. The quality criterion considered is based on the power of the test of data snooping testing procedure. This criterion expresses the probability of the data snooping to identify correctly an outlier. In general, the power of the test is defined theoretically. However, with the advent of the fast computers and large data storage systems, it can be estimated using numerical simulation. Here, the number of experiments in which the data snooping procedure identifies the outlier correctly is counted using Monte Carlos simulations. If the network configuration does not meet the reliability criterion at some part, then it can be improved by adding required observation to the surveying plan. The method does not use real observations. Thus, it depends on the geometrical configuration of the network; the uncertainty of the observations; and the size of outlier. The proposed method is demonstrated by practical application of one simulated leveling network. Results showed the needs of five additional observations between adjacent stations. The addition of these new observations improved the internal reliability of approximately 18%. Therefore, the final designed network must be able to identify and resist against the undetectable outliers – according to the probability levels

Determination and testing of strain parameters in landslide region of Koyulhisar, Turkey

Koyulhisar in Turkey is in danger of landslides, and to determine the risk of landslides in this area, many projects and studies are currently being conducted. Between 2007 and 2008, global navigation satellite system measurements were made, providing data on seasonal effects. The displacements, and also the forces behind these displacements, need to be studied. These forces may be determined using various methods. One method is the determination of strain parameters. With regard to the maximum and minimum principal strain parameters obtained (lambda(1)=56.3433 mu s, lambda(2)=-35.4642 mu s) from the city centre measurements, there is statistically significant stress accumulation in the Koyulhisar region. Furthermore, for the compression and contraction directions obtained in the city centre, compression was obtained in the north-south direction and contraction movement was obtained in the east-west direction. These movement directions show that the tectonic movements in the region have an effect on the landslide.[DPT 2006K 120220]; [CUBAP M368]The GNSS data used in this study were obtained from the DPT 2006K 120220 and CUBAP M368 projects. In addition, GMT (Wessel and Smith 1998) software was used for the map drawings. Kemal Ozgur Hastaoglu and Cuneyt Aydin are gratefully acknowledged for their support and comments. The author would also like to thank the reviewers for their valuable comments that helped to improve the paper