Surface Creep Along the East Anatolian Fault (Turkey) Revealed by InSAR Time Series: Implications for Seismic Hazard and Mechanism of Creep
Tuesday, 15 December 2015
Poster Hall (Moscone South)
Forming the boundary between the Anatolian and Arabian plates in Turkey, the East Anatolian Fault (EAF) is a major tectonic structure in the Eastern Mediterranean region. Together with its conjugate, the North Anatolian Fault (NAF), it accommodates the westward motion of the Anatolian plate with respect to Eurasia. Although it has been associated only with small-to-moderate sized earthquakes in the instrumental period and relatively quiet compared to the North Anatolian Fault, the EAF produced devastating large (M > 7) earthquakes in the historical time (Ambraseys et al., 1998). Analysis of historical seismicity (Nalbant et al., 2001) suggests that a seismic gap exists between the Lake of Hazar and Bingöl, referred here as to Palu seismic gap (PSG) We estimate the interseismic velocity field along the BSG using the Persistent Scatterer InSAR technique (Hooper, 2008). ENVISAT ASAR data acquired between 2003 and 2010 on three adjacent descending and overlapping tracks (T035, T264 and T493) are use to map the interseismic strain accumulation. The results reveal that the 100-km-long section of the Palu segment is exhibiting aseismic creep at the surface. The creep rate varies along the fault reaching, at some places, to the far field GPS-based plate velocity (i.e., 10 ± 0.3 mm/y; Reilinger et al., 2006), implying that significant portion of the elastic strain has been released aseismically. Preliminary modelling with elastic dislocations suggests that some sections of the fault may be creeping from surface down to the entire seismogenic crust. Geology of the fault zone is dominated by ophiolitic and volcanic rocks characterized by weak phyllosilicate minerals, suggesting that aseismic slip is promoted by minerals with low frictional properties. Furthermore, to monitor the surface creep, a GPS network has been established along the Palu segment. One survey has so far been realized and we expect the reliable results in 2 years (supported by TUBITAK no: 114Y250 project).