EAPSI:Aquifer System Storage Response to Canterbury Earthquake Sequence using Satellite Radar and Observation Well Time Series Data

2010-2011年新西兰坎特伯雷地震序列引发了由于地面震动引起的地下水位变化形式的重大水文响应。 鉴于当地居民依赖地下水供应饮用水，必须了解含水层的蓄水能力受到影响的程度。该奖项资助研究，以调查由于地震活动而导致的含水层蓄水率变化的空间范围和幅度。该研究将与GNS Science首席科学家、著名结构和水文地质学专家Simon考克斯博士合作进行。通过分析地面隆起和井口水位的季节性模式，该研究员将估计和比较地震序列之前、期间和之后的弹性含水层存储性。该项目将利用该区域丰富的卫星雷达和油井数据，这些数据是研究含水层与地震相互作用的天然实验室。研究结果将影响其他地震多发地区，包括南加州和田纳西州，以加强重大地震事件后的水管理计划。了解含水层系统与地震断层之间相互作用的时空程度，是减轻与液化有关的灾害和加强水管理计划的一个关键因素。为此，以足够的精度、时空分辨率和空间精度对表面变形进行成像是这一努力的组成部分。 该研究员将使用来自两颗合成孔径雷达卫星（环境卫星和TerraSAR-X）的干涉合成孔径雷达（干涉合成孔径雷达）数据集，包括上行和下行采集几何。重叠区域允许计算垂直和水平位移时间序列，在两个维度上捕获震前、同震和震后变形，包括构造和水文信号。此外，在坎特伯雷和基督城地区有大量的观测威尔斯，具有密集的时间测量。通过比较垂直位移的孤立季节分量和观测井时间序列来估计弹性储存系数。为了分离出信号中的季节性成分，应用小波功率谱分析，识别、分离和重构所需的季节性时间序列。为了确定在地震序列期间存储率是否发生任何增加或减少，在95%置信区间内选择与输入相关的最佳拟合线性值。这项研究将以基督城和坎特伯雷平原为案例研究，最终将帮助其他依赖地下水资源的易受地震危害的地区。 该奖项在东亚和太平洋夏季研究所计划下支持美国研究生的夏季研究，由NSF和新西兰皇家学会共同资助。

The 2010-2011 Canterbury, New Zealand earthquake sequence prompted a significant hydrologic response in the form of groundwater level variations due to ground shaking. It is important to understand the extent to which the storage capacity of aquifers is affected, given the reliance of local populations on groundwater for drinking water supply. This award funds research to investigate the spatial extent and amplitude of the change in aquifer storativity due to the seismic activity. The research will be conducted in collaboration with Dr. Simon Cox, Principal Scientist at GNS Science and renowned expert in structural and hydrogeology. By analyzing seasonal patterns in ground uplift and well head levels, the fellow will estimate and compare elastic aquifer storativity before, during, and after the seismic sequence. This project will use the abundant satellite radar and well data available for the region, which acts as a natural laboratory to study aquifer-earthquake interactions. The findings will impact other earthquake prone regions with active groundwater usage, including Southern California and Tennessee, to enhance water management plans following major seismic events. Understanding the spatiotemporal extent of the interaction between aquifer systems and seismic faults is a key factor for mitigating hazards associated with liquefaction and enhancing water management plans. To this end imaging surface deformation with sufficient precision, spatiotemporal resolution, and spatial accuracy is integral to this effort. The fellow will use Interferometric Synthetic Aperture Radar (InSAR) datasets from two SAR satellites, ENVISAT and TerraSAR-X, in both ascending and descending acquisition geometries. The overlapping areas allow for calculating the vertical and horizontal displacement time series, capturing pre-, co-, and post-seismic deformation in two dimensions including both tectonic and hydrological signals. In addition, observation wells with dense temporal measurements are abundant in the Canterbury and Christchurch region. The elastic storage coefficient is estimated by comparing the isolated seasonal component of the vertical displacement and the observation well time series. To isolate these seasonal components in the signals, wavelet power spectra analysis is applied, and the desired seasonal time series is identified, isolated and reconstructed. To determine if any increase or decrease in storativity occurred during the earthquake sequence, a best-fit linear value relating the inputs is chosen within a 95% confidence interval. This study will use Christchurch and the Canterbury Plains as a case study that will ultimately help other regions prone to seismic hazards that rely on groundwater resources. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Royal Society of New Zealand.