Quantification of Unsteady Fault Slip and Fold Growth, Apennine Front, Italy

这个研究小组提出，盲逆冲断层的核心不断增长的背斜表现出可变的滑动在10,000至100,000年的时间尺度，这种滑动是植根于地壳规模的过程中的应力转移断层之间的气候驱动的过程在地球？s表面。对意大利亚平宁山脉北方山前沿着的研究将描绘两个相关但物理上不相连的断层的滑动历史，分辨率约为20，000年，时间跨度为500万年的上新世-近代。由于这一断层滑动记录与全球气候中众所周知的大幅度振荡相吻合，这种振荡有助于Po前陆的填充和变形，因此该团队进一步假设，10万年甚至4万年的气候周期将反映在观测到的滑动速率中，因为断层通过变化的地下水条件，海平面和结构出现而不同地润滑，以及通过表面沉积物的重新分布来进行差异负载。该项目将采用根据地球轨道运动精确模型校准的无滞后反射磁化循环地层学，这将构成一个高分辨率节拍器，其精度、准确性和连续性优于现代放射性同位素地质年代学、磁性地层学和生物地层学，并超越了分辨率和记录长度问题，而这些问题限制了全球定位系统和古地震方法。断层滑动不稳定性的周期性与已知的40，000 - 100，000年时间跨度的气候周期一致，这将证明这一假设。10，000 - 100，000年分辨率的断层上断层滑动速率变化的知识具有重要的地球动力学意义，特别是对于可能产生重大地震的盲逆冲断层，比如2008年的洛杉矶盆地地震。在北方亚平宁（意大利）山前地区，由盲冲断层引起的类似地震有很好的记录，那里有400万居民，变形率和地震危险仍然很难确定。在这里，地震活动的空间和时间间隔被认为是破坏性地震不会或不会发生的地方。这项研究表明，这种差距只是断层滑动不稳定的结果，旨在通过研究地质记录来确定不稳定的原因。

This research group proposes that blind thrust faults in the core of growing anticlines exhibit variable slip at 10,000 to 100,000 year time scales and that this slip is rooted in crustal-scale processes of stress transfer among faults responding to climatically-driven processes at the Earth?s surface. Studies along the mountain front of the northern Apennines, Italy will delineate the slip history of two related, but physically disconnected faults at a approximately 20,000 year resolution over a five million year Pliocene - Recent time span. Because this record of fault slip coincides with the well-known large amplitude oscillations in global climate that contribute to the filling and deformation of the Po foreland, the team further hypothesizes that the 100,000 year, and potentially 40,000 year climatic cycles will be reflected in observed slip rates as faults are differentially lubricated by changing ground water conditions, sea-level and structural emergence, and differentially loading by the redistribution of sediment at the surface. The project will employ cyclostraigraphy of anhysteretic remanent magnetization calibrated to accurate models of Earth's orbital motions, which constitutes a high-resolution metronome with a precision, accuracy and continuity that outperforms modern radioisotope geochronology, magnetostratigraphy, and biostratigraphy and transcends the problems of resolution and length of record that have limited GPS and paleoseismic approaches. Fault slip unsteadiness with a periodicity in line with known climatic cycles at 40,000-100,000 year time spans will prove the hypothesis.Knowledge of fault slip rate variation on a fault with 10,000-100,000 year resolution has important geodynamic, and seismic hazard implications particularly for the case of blind thrust faults that can generate significant earthquakes, such as the 2008 Los Angeles basin earthquakes. Similar kinds of earthquakes resulting from blind thrust faults are well documented for the northern Apennine (Italy) mountain front, home to 4 million residents where deformation rates and seismic hazards remain poorly defined. Here spatial and temporal gaps in earthquake activity are considered as places where damaging earthquakes do not or will not occur. This research suggests that such gaps are simply the result of fault slip unsteadiness and aims to determine a cause for the unsteadiness by studying the geologic record.