Progressive failure on the North Anatolian fault since 1939 by earthquake stress triggering

Abstract

SUMMARY 10 M ≥ 6.7 earthquakes ruptured 1000 km of the North Anatolian fault (Turkey) during 1939–1992, providing an unsurpassed opportunity to study how one large shock sets up the next. We use the mapped surface slip and fault geometry to infer the transfer of stress throughout the sequence. Calculations of the change in Coulomb failure stress reveal that nine out of 10 ruptures were brought closer to failure by the preceding shocks, typically by 1–10 bar, equivalent to 3–30 years of secular stressing. We translate the calculated stress changes into earthquake probability gains using an earthquake‐nucleation constitutive relation, which includes both permanent and transient effects of the sudden stress changes. The transient effects of the stress changes dominate during the mean 10 yr period between triggering and subsequent rupturing shocks in the Anatolia sequence. The stress changes result in an average three‐fold gain in the net earthquake probability during the decade after each event. Stress is calculated to be high today at several isolated sites along the fault. During the next 30 years, we estimate a 15 per cent probability of a M ≥ 6.7 earthquake east of the major eastern centre of Ercinzan, and a 12 per cent probability for a large event south of the major western port city of Izmit. Such stress‐based probability calculations may thus be useful to assess and update earthquake hazards elsewhere.

Recent behavior of the North Anatolian Fault: Insights from an integrated paleoseismological data set

“…Table A1 summarizes published references to historical earthquakes that may be associated with surface rupture along the NAF [Ambraseys, 2002[Ambraseys, , 1970Ambraseys and Finkel, 1987, 1995Ambraseys and Jackson, 1998;Ambraseys, 2001;Guidoboni et al, 1994;Guidoboni and Comastri, 2005;Nur and Cline, 2000;Nur and Burgess, 2008;Stein et al, 1997;Tibi et al, 2001]. Many of the reported earthquakes come from near Erzincan in the east and Istanbul in the west, while the records from the central portion of the NAF are sparser.…”

“…Earthquakes along the NAF have caused destruction to the region throughout history, which is relatively well documented in a long historical record [e.g., Ambraseys and Jackson, 1998]. Most of the NAF ruptured during the 20th century with a spatiotemporal progressive failure pattern that indicates that the rupture of one segment of the fault casts a shadow of increased Coulomb failure stress onto adjacent segments, increasing their probability of failure [Stein et al, 1997]. This tantalizing glimpse of a crustal stress and strain process during a human lifetime is a rare observation in a science where generally we talk of thousands if not millions of years.…”

Re-evaluation of the surface ruptures of the November 1951 earthquake series in eastern Taiwan, and its neotectonic implications

“…This mechanism has been invoked, for example, to explain the progressive failure of the North Anatolian fault between 1939 and 1999 (e.g., Stein et al, 1997), and to calculate future seismic hazards along the fault (e.g., Hubert-Ferrari et al, 2000;Parsons et al, 2000). In general, after a major earthquake, areas where stress has increased are favored areas for aftershocks and/or subsequent mainshocks occur (Harris, 1998).…”

Investigation of Coulomb stress changes in south Tibet (central Himalayas) due to the 25th April 2015 M W 7.8 Nepal earthquake using a Coulomb stress transfer model

“…Rearrangement of stresses in the crust commonly leads to subsequent damaging earthquakes (Stein et al 1997;Stein 1999;Parsons et al 2000;McCloskey et al 2005). A big earthquake can cause stresses on faults to decrease or increase, and it also alters stresses elsewhere (Parsons et al 2000).…”

“…The Coulomb stress change model has been widely employed to explore the triggering and distribution of aftershocks (e.g., Toda et al 2011;Hayes et al 2014) and other mainshock triggering (Stein et al 1997;Durand et al 2013), and also to investigate regional hazards (Parsons et al 2008;Maccaferri et al 2013). In the similar way, it is necessary to calculate stress transfer in order to probe hazards and fault instability after the M W 7.8 earthquake.…”