Constraints on Quaternary processes in the Eastern Alps from a new detailed image of seismicity

本项目旨在通过对局部震源的多参数研究，估计东阿尔卑斯和南阿尔卑斯/迪纳里德斯过渡带阿尔卑斯地壳的变形。在历史和仪器记录的时间里，该地区发生了大多数最大的高山地震（震级≥6）。这张地震滑动方向和滑动速率的高分辨率地图将有助于更好地理解地壳对造山力的反应。我们假设有争议的阿尔卑斯造山运动的可能驱动因素，即构造，气候和侵蚀，对地震活动模式有不同的印记，他们的详细分析将使我们能够破译不同的贡献。结合大地测量学和古地震学的合作项目，它还将对阿尔卑斯地区古地震、历史地震和未来可能发生的大地震的位置及其复发间隔提供重要的限制。这次地震研究的变形分布将与GPS和InSar的观测结果相结合，这将有助于破译地震与地震变形的作用。将地震活动性和大地测量学与来自结构分析、古地震和侵蚀率的运动学研究相比较，将有助于确定变形是否持续了更长的时间尺度，或者运动模式是否随着时间而改变。该研究依赖于该优先计划（AlpArray, SWATH-D）第一阶段记录的新的丰富地震数据。在第一阶段，我们也将受益于我们自己之前的工作，在那里我们开发了一个有效的事件检测工作流程，适合应用于Alpine网络的大数据量，并实现了能够分析小震级事件的矩张量反演（到目前为止为Mw~3）。我们量化地壳变形的目的需要精确测量基于地震活动性的参数，这些参数可以分为两部分：一方面是精确的震源及其时空模式，另一方面是震源参数的集合（地震矩张量、标量地震矩、应力降和破裂指向性）。第一组将提供活动断层的位置、几何形状、方位和结构非均质性及其分割。第二组将提供滑移方向和滑移速率的补充信息。两者都意味着应用稳健的、成熟的方法，但也意味着采用新的方法来更好地表征观测到的地震活动性（通过图论采用的工具进行地震活动性聚类；力矩张量反演和破裂指向性的结合）。这两个包最终将合并成东阿尔卑斯山和南阿尔卑斯山/Dinarides的地震滑动分布图。

This project is aimed at estimating the deformation in the Alpine crust in the transition zone between the Eastern Alps and the Southern Alps/Dinarides from a multi-parameter study of local earthquake sources. This region hosted most of the largest Alpine earthquakes in historical and instrumental times (magnitude M≥6). The here intended high-resolution map of seismic slip direction and slip rate will help to better understand how the crust reacts to the mountain building forces. We assume that the controversely debated possible drivers of the Alpine orogeny, i.e. tectonics, climate and erosion, have different imprints on the seismicity patterns, and their detailed analysis will enable us to decipher the different contributions. In combination with cooperating projects from geodesy and paleo-seismology it will also provide important constraints on the locations of paleo-, historical, and possibly of future large earthquakes in the Alps and on their recurrence intervals.The distribution of deformation from this earthquake study will be combined with observations from GPS and InSar, which will allow to decipher the roles of seismic vs. aseismic deformation. Comparison of seismicity and geodesy with kinematic studies from structural analysis, paleo-earthquakes and erosion rates will help to determine if deformation has persisted for a longer time-scale or if motion patterns have changed over time. The study relies on the new rich seismological data recorded during the first phase of this Priority Programme (AlpArray, SWATH-D). We will also benefit from our own previous work within the first phase, where we have developed an efficient event detection work-flow suitable for application to the big data volume of the Alpine networks and an implementation of moment tensor inversion capable of analyzing small magnitude events (so far Mw~3).Our aim of quantifying the crustal deformation requires accurate measurements of seismicity- based parameters, which can be grouped in two parts: Precise hypocenters and their spatial and temporal patterns on the one hand and an assembly of source parameters (seismic moment tensors, scalar seismic moment, stress drop and rupture directivity) on the other hand. The first group will provide the locations, geometry, orientation and structural heterogeneity of active faults and their segmentation. The second group will contribute the complementary information of slip direction and slip rates. Both imply the application of robust, well-established methods, but also of novel approaches for a better characterization of the observed seismicity (seismicity clustering by tools adopted from Graph theory; combination of moment tensor inversion and rupture directivity). The two packages will be finally merged to compose a map of seismic slip distribution in the Eastern Alps and the Southern Alps/Dinarides.