Strike‐slip fault geometry in Turkey and its influence on earthquake activity

TLDR

The geometry of Turkish strike‑slip faults has been reviewed and described, and it influences both rupture extent and earthquake behavior. Fault geometry controls large‑earthquake rupture locations, with stepovers wider than 5 km or bends over 30° blocking propagation, while the overall pattern of adjacent bends and stepovers governs strain accumulation, epicenter placement near restraining bends, and aftershock or swarm activity in releasing zones.

Abstract

The geometry of Turkish strike‐slip faults has been reviewed and described. From this data set it appears that fault geometry (the distribution of discontinuities such as bends and stepovers along the main fault trace) plays an important role in controlling the location of large earthquake rupture segments along the fault zones. Large earthquake ruptures generally do not propagate past individual stepovers that are wider than 5 km or bends that have angles greater than about 30°. More important than the size of each discontinuity, however, is the total “geometric pattern,” i.e., the distribution of adjacent bends and stepovers based not only on distance from one another but also on relative discontinuity size. Certain geometric patterns (restraining single or double bends) are particularly common and can be viewed as responsible for strain accumulation along portions of the fault zone. Fault geometry not only plays a role in the extent of earthquake rupture but also in characteristics of earthquake behavior. For example, large earthquake epicenters often occur near restraining bends or double bends. Furthermore, aftershocks and swarm activity can often be associated with releasing areas (areas along the strike‐slip fault that are undergoing a relatively large amount of extension).