Salt Kinematics after Earthquake
Abstract
Salt extrusions are simple natural models. The shapes of salt extrusions are complex gauges of the forces extruding them [9]. The uplift rates of a part of the Namakdan is between 1-3 mm/y-1 at the rim to 3-6 mm/yr-1 in the interior [5]. The salt glacier flowed plastically during the brief annual rainy season [6].The salt flow faster with temperature rise and flow slowly when temperature fall [3]. The displacements with>10cm/y and >50 cm/y suggest that, the salt extruded with rate 82 mm a-1 [9] but spread cm to m per year [8].The recent InSAR study Near Namakdan had no explanations about high activity of salt after earthquake [10].The coseismic vertical displacements suggest reactivation of blind thrust [11] .Our recent field measurements reported here suggest that any fast flow in salt may related to the mild to strong Earthquakes and may caused by diapiric reactivation. The earthquake of 27Nov 2005 with Mw ~ 6 occurred in Qeshm Island has a distance of 65 km to Bandar Abbass.The base of our measurements illustrated by Aftabi[1,2]and suggested by Bailly[4].Two wooden stakes about 50 cm in length and (2x3 cm<) in section were hammered vertically into the surficial marly salt along a line on the SW slopes of the thin southern namakier of Namakdan. Two others hammered on the walls of the cave in the south western part of the Namakdan diapir. The distance between stakes was measured (+/- a mm and cm) using a meter scale and the azimuths between them were measured (+/- a degree) by compass. Between readings, the meter scale was stored and carried in an ice chest to minimize its thermal expansion or contraction. Readings were made immediately one and two day after in the same times after installation measurements. We expected repeat of the main shock as mild earthquake one year later as earthquake cycling, we therefore return there and measured distance between stakes in salt one year after main shock but in the same times.IIEES reported the 26 and 27th 06 mild earthquake with Ml 3.3[12]. The distances between stakes both lengthened between measurements demonstrating local extension strains in the tiny southern namakier of Namakdan inside the cave and out in the marly cover.We interpreted some big activities in our 05 InSAR image as brine movements in the rim of the salt.Some of the distances between stakes exhibited complete elastic recovery during one day [1]. Others time-dependant elastic-plastic recovery[1], while in the Namakdan diapir the stakes just extended rapidly in scale of 1cm after 24 hours indicate permanent non recoverable plastic strains[1]with high rate after earthquake.With special thanks to M.Madani, C.J.Talbot and E.Feilding. REF: [1]Aftabi, P., 2000[2]Aftabi, p. et al, 2005[3]Aftabi, P., 2006[4]Bailly, E.B, 1931[5]Bruthans, J et al,In Press [6]Talbot, C.J., & Rojers, E.A.1980[7]Talbot, C.J, 1998[8] Talbot, C.J et al., 2000[9]Talbot, C.J, &Aftabi, P., 2004 [10]Nilforoushan, F. et al., 2005[11]Niessen et al.,In press [12] www.iiees.ac.ir
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFM.T43B1360A
- Keywords:
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- 8003 Diapir and diapirism