Geodynamics Research International Bulletin

6

Authors: Mehrdad Ansaripour, Mehdi Rezapour

The Mn 6.1 Dashti earthquake occurred at 16:24:49 local time, 16:24:49 UTC, on 9 April 2010, in Boshehr province, southwest Iran. Dashti earthquake occurred near a distance of 80 km of Bushehr port. This earthquake has many aftershocks and its aftershocks still occur in the region. The study area is a part of the central Iran seismotectonic province. The tectonics of the region is dominated by a convergence between the Arabian and Eurasian plates. When earthquakes occur in an area, especially if they occur frequently indicates that a fault is active and ruptured. The aftershock locations show a trend of NW-SE, which is interpreted as the fault plane of the mainshock. The study of the spatial distribution of the aftershocks of this earthquake shows that the Pishani-Kohestan fault is the cause of the earthquake.

8

Authors: Seyed Reza Mehrnia

Using fractal equations within an integrative algorithm of Fibonacci sequences is a new approach toward spatial prediction of great earthquakes with emphasized investigations on earthquake catalogue in north east of Saravan (1929-2013) and potentials by this research. Analytical results indicate growing up of self-similarities due to a magnitude geostatistical interpolation. Therefore, the fractal dimension of magnitude-area power law function is in coincidence with Golden Ratio influences (1.618). It means that the focal mechanism of Saravan great earthquake (M: 7.7, 16 April 2013) had close relation with pre-seismic parameters including co-appearances of self-similarities, variation of fractal dimensions and relative stability of Fibonacci ratios that are introduced to facilities of current research technique for great earthquakes prediction.

11

Authors: S.A.Mahmood, Z. Waheed, H. Batool, S. Ghazi, S. Mirza, A.M. Akhtar, S.M.H. Raza and R.M.A. Khan

The disastrous tremor of Hazara Kashmir Syntaxis (HKS) in Pakistani Himalayas on October 8, 2005 was a result of neotectonic movement through the advanced propagation of the NW- end of Indo-Pak subducting plate below Eurasia. The purpose is to observe neo-tectonics and allied active deformation through SRTM DEM 90 m based automated drainage network and geomorphometry. The geomorphic indices such as Hack-SL gradient, steepness, concavity and relative uplift rate maps are quite significant for the analysis of active tectonics. A comprehensive river longitudinal profile analysis discovered that the outcomes achieved for the topographic relative uplift rates (TRUR), steepness, Hack SL and concavity indices are reliable with the active tectonics of HKS. The TRUR are higher in the central, north-northeast, north-northwest and south-southwest (i.e., 2. 5 mm/yr.) in comparison with the lower (0.1 mm/yr.) in the eastern part of HKS. This scenario proposes neotectonic control over the local drainage network and the topography in the study area. The TRUR map confirms that the central, NNE, NNW and SSW parts of the study area tectonically more deformed and uplifted than region in the east towards Sri Nagar basin. The spatial distribution of variable relative uplift rates is a clear indication of unique and complex active deformation along and in the HKS.

11

Authors: Mohammad Reza Mahdevar., Zahra Kamali , Babak Samani, Ali Asghar Moridi

Kinematic analysis of faults show development of normal, reverse and strike slip faulting in the area. Folding in the study area mainly shows inclined fold axial surface with NW-SE fold axes trending and NW plunging. The analysis of fault plane geometry and slickenlines in order to reconstruct the orientations of effective stress using graphic method (fault-slip inversion technique) was performed. Results show the attitude of principal stresses axis for 1) Normal faults, 2)reverse faults and 3) strike slip faults, as follow: 1) σ1: N85W/86, σ2: S30W/10, σ3: S55E/27. 2) σ1: S60W/14, σ2: N30W/23, σ3: N90E/81 and 3) σ1: N86E/5, σ2: N0E/73, σ3: S0E/45). The amounts of stress shape ratio (φ) were calculated as φ=0.79, φ=0.35 and φ=0.5 respectively for normal, reverse and strike slip faults. The mean value of strain ellipsoid shape parameter (r0= 0.39) shows the general three axial flattening in the study area.

12

Authors: Manijeh Ghahroudi Tali

Khoye and Salmas provinces are located in seismically mountainous northwestern Iran. Study of causes of mass movements in the region indicated influence of earthquake stimulant. This study was done aimed to determine the effects of earthquake-induced on mass movement's instability in the provinces. The data were used included 1:25000 topographic and land use maps, railway, major faults, earthquake magnitude (Mw) during 1930 to 2008, Local magnitude of earthquake in 2000 (ML) and field work. Research method used in seismic zonation was exponential semi-variogram model with ordinary Kriging. Curvature, slope and distance of the fault variables were prepared respectively Curvature, Slope and Distance functions. Weighted Sum model was used to combine data and the validation was performed by variance analysis. The results were assessed based on railroads as structurally vulnerable. Finally, it was determined that the stimulatory the earthquake effect on the occurrence of mass movements and, especially landslides in slopes of Khoye and Salmas provinces and it increases in areas with the slope greater than 8 degree, the convexity terrain, close proximity to faults and earthquakes more than magnitude 4.

16

Authors: Jafar Rahnema Rad, Majid Nemati

Saravan earthquake which occurred on 16 April.2013 with Mw 7.8 and depth of 95 kms struck southeast Iran, Sistan and Baluchestan province. Its reverberations were felt as far away as neighboring countries. The earthquake had a normal mechanism and occurred in Saravan fault zonation. The focal depth of the earthquake ranged from 50 to 95 kms and its magnitude was estimated to be 7.5 to 7.8. According to observations and field investigations, near Hampanik village in southwestern Gosht city, a 2-km systematic surface fracture with northwestern-southwestern trend, along Saravan fault was observed as a reactivated structure which has an En –Echelon pattern. The maximum magnitude of the earthquake was VII in MMI scale. Since the earthquake originated so deep underground, and in such a sparsely populated area, it caused relatively few casualties and only minor damage. But this earthquake led to the reactivation of sulphur and Travertine springs, sand liquefaction, water level rise of Qanats, creation of surface ruptures, reactivation of old linear structures, lime mountain landslides, Mount Taftan, Mount Birak, destruction of the walls of the buildings which were perpendicular to direction of the force propagation.