EARTHQUAKE DEFORMATION STUDY USING SAR INTERFEROMETRY, A CASE STUDY IN PAMIR-ALAI AREA, KYRGYZ REPUBLIC Chandima N. Subasinghe 1 , Teshebaeva Kanayim 2 , M. K. Hazarika 1 , Lal Samarakoon 1 1 E-mail: GeoInformatics Center, Asian Institute of Technology, P.O Box 04, Klong Luang, Pathumthani 12120, Thailand; Tel: +662 524 6148; Fax: +662 524 6147; chandima@ait.ac.th , manzul@ait.ac.th , lal@ait.ac.th 2 E-mail: Central Asian Institute for Applied Geosciences, 73/2 Timur Frunze, 720027 Bishkek, Kyrgyz Republic; Tel: +996 312 555454; k.teshebaeva@caiag.kg KEY WORDS: ALOS PALSAR, DInSAR, differential fringes, faults, Line of Sight (LoS) displacement ABSTRACT: Kyrgyz Republic is a disaster-prone country due to its geographical location in an active seismic zone and its mountainous landscape. For the past 100 years, 11 earthquakes were recorded in vicinity of Nura village, each having magnitude above 6 and intensity above 5. On October 6, 2008 Pamir-Alai area was hit by a magnitude 6.6 earthquake and cracks along Irkeshtam road were observed and measured after the earthquake and it is assumed that unrevealed deformation has occurred in surrounding areas of Pamir Alai Mountains. Through DInSAR technique it is possible to measure very small displacement and gives clear understanding of the nature of the earthquake over extensive spatial extent. ALOS PALSAR images were used to calculate the coseismic deformation because only L band SAR derived images are capable of detecting the deformation over the land area including vegetated, forested or snow covered regions.22 ALOS PALSAR images were processed by using ENVI SARscape 4.2 software package and topographic related phase was removed by using SRTM 3-arcsec DSM. After overlaying available fault data on top of the filtered, mosaiced and geo-coded differential interferogram, it was observed that the obtained differential fringes were corresponding with the available fault data in Pamir-Alai region. Major deformation was observed in North-West direction from the epicenter and the regions where differential fringes were observed also show presence of a reverse thrust fault and normal faults. 1. INTRODUCTION Pamir region of the Kyrgyzstan is located at the northern edge of the India-Eurasia collision zone and also considered as a typical inter-continental high altitude glacier region which has a long history of catastrophic disaster such as earthquakes, landslides, wind storms, snow avalanches and epic Floods. On October 6, 2008 Pamir-Alai area was hit by a magnitude 6.6 earthquake and epicenter was estimated to be at 39.51N, 73.72E according to the Kyrgyz Seismological Institute. After the earthquake some fieldworks had carried out by Central Asian Institute for Applied Geosciences along the Irkeshtam road and the vicinity of Nura village to examine the cracks occurred by the earthquake. Due to the inaccessibility of the area it is assumed that unrevealed deformation has occurred in surrounding areas of Pamir Alai Mountains. Over the past decade repeat pass SAR interferometry has proven its ability of detecting the crustal deformation due to earthquakes at a high spatial resolution so it is advisable to incorporate this