جستجوی مقالات مرتبط با کلیدواژه « بیشینه شتاب زمین » در نشریات گروه « جغرافیا »

One of the main issues in drainage watersheds is erosion and sediment yield. Lack of proper management in this field can be environmental hazards and even a threat to human life. The purpose of this study is fingerprinting the sources of sediment yield in sub-basins 1 and 2 of Talar drainage basin in Mazandaran province.140 soil samples in first approach and 80 samples in second approach collected respectively sub-basin 1 (77) and (47), sub-basin 2 (63) and (33) of lithological units and range of peak ground acceleration and 20 drape sediment samples at the outlet sub-basins and 28 geochemical elements measured as tracers in the samples. Using the Kruskal-Wallis test and discriminant function analysis, the composite fingerprints was determined. The largest relative contribution of sediment yield based on the Bayesian un-mixing model is in the first approach (sub-basin 1 unit sandstone and conglomerate with 59.1%, sub-basin 2 unit marl and shale with 47.2%), in the second approach (sub-basin 1 unit the range of peak ground acceleration at the level (0.51-0.6) g with 50.3%, and sub basin 2 units channel bank with 64.6%). The results of this study showed that the range of peak ground acceleration have a direct effect on control of sediment yield and erosion processes. Also, division of lithological groups as sources sediment yield based on range of peak ground acceleration, which have a great impact on sediment yield, as a new approach, can be of great help in understanding sediment yield processes.

Considering devastating events like the 2003 Bam earthquake (M_w~6.6), it is essential to develop up-to-date earthquake hazard maps to design structures in this area. In this study, a seismic catalog including historical and instrumental events was compiled and then 21 seismic sources were identified in Kerman province and its surrounding. Seismicity parameters were estimated for all 21 source zones and an attenuation relationship was selected to obtain local site effect-based seismic hazard maps. Finally, seismic hazard maps, which is one of the basic requirements of seismic design and seismic regulations, were presented in form of the peak ground acceleration (PGA) measures for the return period of 475 and 2475 years, and the high risk areas in Kerman Province were introduced. To investigate the depth of events on Iranian plateau, according to the studies conducted in this study, it is suggested to use only the data obtained from local seismic networks. The results were presented as seismic hazard maps for the parameters of maximum intensity of horizontal ground acceleration, taking into account construction effects with a probability of 2% and 10% over 50 years for all parts of Kerman province to provide all design needs according to 2800 regulations. Using the obtained maps, the earthquake parameter in the Iranian Seismic Code (Code 2800) can be updated. Results showed that, as expected, two areas in Kerman province are with the highest accelerations: The first is the Kuhbanan-Golbaf-Bam fault systems with a northwest-southeast trend and the second is the northeast termination of Zagros toward Makran. Both of these ranges are seismic and of great importance in seismic surveys. These areas include Kuhbanan-Golbaf-Bam fault systems and Jiroft-Kahnooj.

In this research, the prediction of Peak Ground Acceleration (PGA) is investigated through training the Adaptive Neuro Fuzzy Inference System (ANFIS) network using data partitioned into inlier and outlier groups. The partitioning procedure is based on an automated method which uses K Nearest Neighbor (KNN) search and Local Linear Model Tree (LOLIMOT) methods. The mentioned proved to enhance the prediction procedure at least 36 percent with respect to normal training mode with no data partitioning. Hereafter, a PGA catalogue reported by the Iranian ground acceleration network with 1571 records was used and the trained network was used for predicting the PGA map around the Mormori, 2014 earthquake epicenter. We used spatial information of the epicenter and the site, earthquake magnitude, Vs30, depth of the hypocenters and the epicentral distance foe the sites. The resulted map adapts well to the official report of the mentioned earthquake for the PGA analysis published by the International Institute of Earthquake Engineering and Seismology (IIEES). Finally, it is concluded that using machine learning algorithms could be beneficial in the cases where adequate data-sets are not provided by the seismological networks specifically in the concept of the strong ground motion analysis.

WARED system is Internet-based software that automatically receives the seismic information from Iran seismic center (ISC) every 10 seconds. The information is processed in a few seconds and damage assessment maps of various parts of the city (such as buildings, hospitals, bridges, etc.) become available, in layered format, to rescue groups through system site. WARED system based on the population exposed to each Peak Ground Acceleration (PGA) level, it estimates the losses from earthquakes in residential areas. This system was implemented in the municipality of Mashhad (North East of Iran) in January 2014. Principles of information processing in this system depend on three main factors including the magnitude and location of earthquakes, the properties of the rocks and sediment the earthquake waves travel through, and the technical characteristics of the buildings (strength, age, type, and geotechnical conditions of soil, etc.). Therefore PGA is used as the most important parameter to assess the damages and fatality occurred. Primary purpose of WARED system is rapid dissemination of earthquake impact assessments for decision-making purposes. This is motivated by the idea that an estimated range of damage and number of deaths will aid in decisions regarding humanitarian response.

Khark Island is located in the southern margin of the Zagros folded belt in the northeast of the Arabian plate. This study is focused on active geological characteristics of the area understudy, where there is defined 11 seismogenic zones. The seismicity parameters are assessed for these zones based on seismicity characteristics, as well as the return period of the earthquakes. Using the reliable attenuation relationships, the seismic hazard zoning maps are developed in which the PGA of 0.36 is found for the 475 years return period.