Quaternary tectonics of the North Anatolian fault zone and its environs

北安纳托利亚断裂带（NAFZ）的最西端被认为是过渡性质的，从东部的主要横向构造体制在土耳其西部和爱琴海的伸展构造体制。我们分析了晚第四纪地表变形和周围这：NAFZ的一部分，使用SPOT和COSMOS图像，有限的实地观察被用作地面实况。获得了以下结果：1.更新世地貌表面上的断层错距在卫星图像上可见，而全新世表面上发育的断层错距则不可见。卫星图像上探测到的活动断层痕迹几乎与1944年、1957年和1967年地震的地表破裂完全吻合。Mudurnu山谷以西的NAFZ分为两个活动断层带：北部的lzmit-Sapanca断层带和南部的lznik-Mekece断层。伊兹尼克-梅克切断层以走滑为主，由一条简单、连续的链组成;其西部存在相当大的倾滑分量。相反，晚第四纪变形在lzmit-Sapanca断裂带是相当矛盾的。我们对卫星图像的解释和有限的实地观察表明，该断裂带的第四纪地表变形是挤压性的，尽管微震的断层面解（Evans等人，1985年）表明，transtensional运动目前占主导地位。我们推测，在孕震深度（>6公里）的断层的几何形状是不同的，在表面。

The westernmost portion of the North Anatolian fault zone (NAFZ) has been believed to be of transitional nature from the dominantly-transcurrent tectonic regime in the east to the extensional tectonic regime in western Turkey and the Aegean Sea. We analyzed late Quaternary surface deformation in and around this : portion of NAFZ, using SPOT and COSMOS imagery ; limited field observations were employed as ground truth. The following results were obtained :1. Fault offsets on Pleistocene geomorphic surfaces are visible on satellite imagery, whereas those developed on Holocene surfaces are not. Active fault traces detected on the satellite imagery coincide almost exactly with the surface breaks associated with the 1944, 1957 and 1967 earthquakes.2. NAFZ west of the Mudurnu Valley branches into two active fault zones : the lzmit-Sapanca Fault Zone on the north, and the lznik-Mekece fault on the south. The Iznik-Mekece fault is dominantly strike-slip and consists of a simple, continuous strand ; a considerable dipslip component exists on its western portion. In contrast, late Quaternary deformation in the lzmit-Sapanca Fault Zone is quite paradoxical. Our interpretation of satellite imagery and limited field observations indicate that Quaternary surface deformation in this fault zone is compressional, although fault plane solutions of microearthquakes (Evans et al., 1985) suggest that transtensional movements are presently dominant. We speculate that the geometry of faults at seismogenic depths (>6 km) is different from those at the surface.