Integrating Geologic, Geodetic, and Coastal Tide Gauge Observations with 100-year Vertical Deformation Models of California Earthquake History

该项目综合了沿海验潮仪、大地测量和太平洋-北美板块边界的地质数据，研究了地震引起的垂直形变。虽然该区域不断增长的空间大地测量数据档案提供了高空间覆盖率的精确形变测量，但这些数据只提供了15年的地壳运动记录，因此对地壳运动随时间变化的限制很弱。地质数据提供了1000年的平均变形记录，然而这些数据通常位置稀疏，可能具有很大的不确定性。或者，在过去的50-100年里，加州海岸线上的几个验潮站连续记录了海平面的变化。这些站提供了海平面变化的时间记录，通常被归因于冰川后的反弹和海洋气候现象。然而，地质过程，包括大地震的位移，也被证明会产生海平面变化，因为垂直的震间应变积累可以贡献1-3毫米/年的抬升和下沉速率。利用沿海验潮仪时间序列数据，该项目正在探索海平面变化与由三维地震周期变形模型产生的垂直位移之间的相关性，该模型受地质滑移率、大地速度和圣安德烈亚斯断裂系统沿线的历史地震数据的约束。由地质和大地测量约束模型得到的一阶垂直形变估计与海平面的长期趋势高度一致，但需要进一步的分析来彻底探索模型参数空间，并调查失配和未建模的现象的来源。该项目将整合100年的沿海验潮仪数据(平均海平面永久服务)、过去15年的大地测量数据(地球示波器板块边界观测站连续GPS和InSAR)以及一个新的地质数据库(南加州地震中心地质垂直运动图)。这项研究调查了构造变形对过去100年加州海岸线记录的海平面变化的长期作用。通过这样做，这些研究活动通过进一步促进我们对断层系统地壳动力学、地震灾害和数据合成的理解，为美国国家科学基金会S地球范围倡议的目标做出了贡献。这项调查产生的数据和模型产品将为教育和提高公众对加州过去和现在的地震危险的认识提供更好的基础设施。此外，由于加州大地震有可能造成巨大的经济和人员损失，定量的地震危险性评估依赖于对加州构造运动的准确描述，对地震科学的进步至关重要。

This project investigates earthquake-induced vertical deformation using a synthesis of coastal tide gauge, geodetic, and geologic data of the Pacific-North American plate boundary. While the growing archive of space geodetic data in this region provides precise deformation measurements with a high degree of spatial coverage, these data supply only a 15-year record of crustal motions and therefore only weakly constrain time-dependence of crustal motions. Geologic data provide a 1000-year averaged record of deformation, however these data are often sparsely located and can have large uncertainties. Alternatively, sea level change has been continuously recorded along the California coastline at several tide gauge stations for over the past 50-100 years. These stations provide a temporal record of sea level change, generally attributed to post-glacial rebound and ocean climate phenomena. However, geologic processes, including displacements from large earthquakes, have also been shown to produce sea level variations, as vertical interseismic strain accumulation can contribute uplift and subsidence rates of 1-3 mm/yr. Using coastal tide gauge time series data, this project is exploring the correlation between sea level variations and estimates of vertical displacements produced by a three-dimensional earthquake cycle deformation model that is constrained by geologic slip rates, geodetic velocities, and historical seismic data along the San Andreas fault system. First order vertical deformation estimates derived from geologically and geodetically constrained models are highly compatible with long-term sea level trends, however further analysis is needed to thoroughly explore model parameter space and investigate sources of misfit and unmodeled phonomena. The project will integrate 100-year coastal tide gauge data (Permanent Service for Mean Sea Level), geodetic data (EarthScope Plate Boundary Observatory continuous GPS and InSAR) spanning the last 15 years, and a new geologic database (Southern California Earthquake Center Geologic Vertical Motion Map).This study investigates the long-term role of tectonic deformation on sea level change recorded over the past 100 years along the California coastline. In doing so, these research activities contribute to the objectives of NSF?s EarthScope Initiative by further advancing our understanding of fault system crustal dynamics, earthquake hazards, and data synthesis. The data and model products generated by this investigation will provide an enhanced infrastructure for education and public awareness of both past and present earthquake hazards in California. Furthermore, because a major California earthquake has the potential for massive economic and human loss, quantitative seismic hazard estimates, which rely on an accurate characterization of tectonic motions in California, are critical to the advancement of earthquake science.