Geodynamics Research International Bulletin

6

Authors: Mehrdad Pazhoohan (Pourzarghan)٫ Mehran Arian٫ Manochehr Ghorashi٫ Khosro Khosrotehrani

Tectonic plates are constantly moving. Thus, determining the location of the regions with earthquake potential has always been the geologists challenge. One of the new methods which follow observations of tectonic movements and earthquakes is the application of the knowledge of tectonic geomorphology. Studying and measuring landscapes and forms made by active tectonics is one of the objects of morphologic science. Active tectonic movements in a region are recorded in the morphology of rivers, drainages, alluvial fans and mountain fronts. The rivers respond to active tectonic movements, so the study of these phenomena can have an important role in locating the active tectonic regions. Ghareh Aghaj River originates from North East of Kazeroon in Fars province and flows into Persian Gulf while passing Bushehr province. This river is in the folded Zagros zone. Tadvan region in the South West of Iran has responded to ongoing tectonic deformation and has shown some geomorphological features. Due to Arabian–Eurasian collision the uplift and lateral tilting occurred in the study area, and they are manifested in avulsion, truncated streams and oriented drainage network. Such geomorphic features have been identified on the satellite images and interpreted through DEM and field observations. The fluvial features in the study area show uplift in one side of Ghareh Aghaj River which has caused lateral tilting in the area.

7

Authors: Mohammad Aryamanesh

This paper investigates the 2001 Gujarat earthquake, one of the world’s most destructive earthquakes, which occurred in western India. The method used in this study was based on gravity data and satellite image processing. The EGM-2008 global gravity model has been used as the reference data. Thus, in the first place, the afore-mentioned gravimetric data was processed by using Oasis Montaj 7.0.1 Software. Then, in order to trace the edge of the buried anomalies in a better way, it was tried to apply the total horizontal gradient filter. Next, to complete the hidden lineaments location, a combination of gravity gradient components was used. Afterwards, Special Function Method (SFM) was used to achieve precise positioning of the depths and the trends of the hidden gravity lineaments. Finally, they were compared with the earthquake focal depths. All the obtained results were compared with earthquakes epicenter using satellite images. The performed analysis and the results of the interpretation of the gravimetric data indicate that there is a significant correlation between focal depths and the depths obtained by this method. Thus, it can be concluded that this method can help us to estimate the depths of the future earthquakes.

9

Authors: Mehdi Zare, Fereidoon Sinaiean

Site effect could be strongly affected by the earthquake ground motions and highly change the pattern of damages. Even though different methods are proposed for the study of site effect, most of them are time consuming and costly. There are more than 1100 accelerographic stations in Iran Strong Motion Network (ISMN) and it will take a great deal of time and money to study site classification. ISMN have recorded more than 3200 reliable three-component accelerograms in 620 stations from 1994 to 2003, which constitute a rich database for this investigation. We tried to compare the results of Vs-30 obtained from geoseismic measurements and H/V spectral ratio using the recorded accelerograms to modify the previous criteria for a fast and reliable classification. The final results show the convenience of the newly- defined criteria that could be used with more confidence for the stations with more records.

12

Authors: S.A. Mahmood, U. Alvi, J. Sami, J. Qureshi, A. Masood, Sahar Mirza, S.M.H. Raza

North-East and East-West oriented neotectonic activity, abrupt slope and differential erosion in Parachinar Syntaxis (PCS) make up a perfect natural laboratory and deliver a significant prospect to examine neotectonic influence on its landscape evolution. In this research, geomorphometric characteristics of PCS in north-western Pakistan are assessed through DEM-based hypsometric analysis of Strahler order 5 subbasins. One hundred and eleven Strahler order 5 subbasins were extracted automatically from SRTM 90 m using D8 algorithm. Hypsometric integrals (HIs) and hypsometric curves (HCs) for each singular subbasin were computed to estimate the gradation of erosional stages and the elements governing these changes. HIs and HCs were computed using zonal statistics through the maximum, minimum and mean elevations. The convex up curve shows less eroded subbasins and they are located along and the Spinghar Thrust and North-west margins of Khowst Plateau which is an indication that PCS is tectonically active, while the S-shaped curves represent the intermediate erosion stage and they are located within and south-east of the HKS. The concave down curves indicate maximum erosional stage and they are located near Kabul Block. Higher values of HIs and shape of the HCs correspond to neotectonic control of the landscape of PCS.