Collaborative Research: How Constant are Fault Slip Rates in Time and Space? An Analysis of the North and East Anatolian Faults, Turkey

研究小组正在研究断层加载和应变释放速率在时间和空间上恒定(或非恒定)的程度。他们在解决这一根本重要问题方面的工作侧重于在土耳其的北安纳托利亚断层和东安纳托利亚断层的不同时间尺度上产生断层滑移率。由于土耳其安纳托利亚-欧亚-阿拉伯板块边界的结构相对简单，这些断层是拟议研究的特别有吸引力的目标。具体地说，大地测量和地质数据表明，在土耳其中部和东部，几乎所有的板块边界应变都是由这两条断层上的滑动所调节的。调查人员正在将他们的努力集中在一个日益显得关键的观测时间尺度上--历史和古地震数据记录的时间不规则应变释放之间的时间范围，以及断层滑移率似乎相对恒定的较长时间尺度。通过使用偏置地貌特征的宇宙成因核素测年技术，得出地貌表面暴露于地球表面宇宙射线的持续时间，他们将确定这两个断层沿线八个或更多地点的滑动速率，时间尺度从大约1.500年到10 000多年不等。他们的结果与美国、土耳其和日本研究人员正在进行的对这些断层的古地震应力分析相结合，将能够确定安纳托利亚-欧亚-阿拉伯板块边界内应变释放在时间和空间上的变异性。这些数据反过来将为断层加载机制的现实地球动力学模型提供必要的基本约束。同样重要的是，来自土耳其相对简单的板块边界的数据将提供一个重要的比较点，与来自机械上更复杂的板块边界(例如，加利福尼亚州的太平洋-北美板块边界)的类似数据进行比较。

The research team is studying the degree to which fault loading and strain release rates are constant (or non-constant) in time and space. Their work in addressing this fundamentally important issue focuses on the generation of fault slip rates at a variety of time scales a long the North and East Anatolian faults in Turkey. These faults are particularly attractive targets for the proposed research because of the relative structural simplicity of the Anatolia-Eurasia-Arabia plate boundary in Turkey. Specifically, geodetic and geologic data suggest that in central and eastern Turkey almost all plate boundary strain is accommodated by slip on these two faults. The investigators are focusing their efforts on what increasingly appears to be a critical time scale of observation - the time range between the temporally irregular strain release documented by historical and paleoearthquake data, and longer time scales over which fault slip rates appear to be relatively constant. By using cosmogenic nuclide dating of offset geomorphic features, a technique that yields the duration of time that a geomorphic surface has been exposed to cosmic rays at the earth's surface, they will determine slip rates at eight or more sites along these two faults at a variety of time scales ranging from approximately 1.500 to greater than 10,000 years. Their results, in combination with ongoing paleoseismolgic analyses of these faults by U.S., Turkish, and Japanese researchers, will allow determination of the variability of strain release in time and space within the Anatolia-Eurasia-Arabia plate boundary. These data, in turn, will provide basic constraints necessary for realistic geodynamic models of fault loading mechanisms. Equally importantly, the data from the relatively simple plate boundary in Turkey will provide an important point of comparison with similar data from more mechanically complex plate boundaries (e. g., the Pacific-North America plate boundary in California).