Onset of aseismic creep on major strike-slip faults

Abstract

International audienceTime series analysis of spaceborne synthetic aperture radar (SAR) data, GPS measurements, and fi eld observations reveal that the central section of the Izmit (Turkey) fault that slipped with a supershear rupture velocity in the A.D. 1999, Mw7.4, Izmit earthquake began creeping aseismically following the earthquake. Rapid initial postseismic afterslip decayed logarithmically with time and appears to have reached a steady rate comparable to the preearthquake full fault-crossing rate, suggesting that it may continue for decades and possibly until late in the earthquake cycle. If confi rmed by future monitoring, these observations identify postseismic afterslip as a mechanism for initiating creep behavior along strike-slip faults. Long-term afterslip and/or creep has signifi cant implications for earthquake cycle models, recurrence intervals of large earthquakes, and accordingly, seismic hazard estimation along mature strike-slip faults, in particular for Istanbul which is believed to lie adjacent to a seismic gap along the North Anatolian fault in the Sea of Marmara

Recent tectonic features of the central part (Bolu-Corum) of the North Anatolian Fault

“…by Karabacak et al (2011) [9] to calculate the rate of 6.8-10.0±4.0 mm/yr and 9.1-10.1±4.0 mm/yr. Cakir et al, (2012) [2] and Cetin et al, (2014) [3] reported that the rate is not stable along the fault and reaches a maximum of 20±2 mm/ yr 20km to the east from Ismetpasa (Figure 3 and 4).…”

Determination of Aseismic Deformation on North Anatolian Fault in Ismetpasa and Destek Regions Using GPS Data, Turkey

“…The important point of the creep is the threshold of the aseismic slip rate. If the creep motion has velocity equal or longer than long-term slip rate along the fault, the fault will continue to slip freely and will not produce destructive earthquake (Cakir et al, 2012). Conversely, if the aseismic slip rate is lower than the long-term slip rate of the fault, it is possible that the fault can produce the destructive earthquake (Karabacak et al, 2011).…”

“…The LIDAR technology was also used by Karabacak et al (2011) to calculate the rate of 6.8-10.0±4.0 mm/yr and 9.1-10.1±4.0 mm/yr. Cakir et al (2012) and Cetin et al (2014) reported that the rate is not stable along the fault and reaches a maximum of 20±2 mm/yr 20km to the east from Ismetpasa (Figure 3 and 4). Another aseismic creep segment on the NAF was reported by Karabacak et al (2011) in Destek village on the northeast of the Corum.…”

“…When the yielding stress (friction plus effective normal stress) on the fault is reached, the fault suddenly slips and produces an earthquake, releasing the accumulated energy (Cakir et al, 2012). However, some faults are known to slip aseismically at the surface down to some depths, accumulating little or no strain and thus producing less frequent or no earthquakes, respectively (Burford ve Harsh, 1980;Steinbrugge et al, 1960;Cakir et al, 2005).…”

“…However, some faults are known to slip aseismically at the surface down to some depths, accumulating little or no strain and thus producing less frequent or no earthquakes, respectively (Burford ve Harsh, 1980;Steinbrugge et al, 1960;Cakir et al, 2005). Therefore, it is essential to determine the presence and characteristics of such aseismic motions, known as surface creep (a phenomenon rarely observed along active strike slip faults) when determining seismic hazard of a region (Bürgmann et al, 2000b;Cakir et al, 2012).…”