Collaborative Research: Geodetic imaging of the interplay between creep, locking, earthquakes and land subsidence along the Chaman plate boundary

合作研究：查曼板块边界蠕变、锁定、地震和地面沉降之间相互作用的大地测量成像

• 批准号: 2028557
• 负责人: Roger Bilham
• 金额: $ 18.43万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-15 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2028557&HistoricalAwards=false
• 关键词: Collaborative; Research; Geodetic; imaging; interplay

For the past 50 million years, processes deep within the Earth have forced the Indian subcontinent to collide with the Asian continent. In the north the high mountains and earthquakes of the Himalaya are evidence of this continued collision. Less well studied, the 700-mile-long western edge of the subcontinent between Karachi and Kabul is marked by several large faults similarly plagued by damaging earthquakes. Although none have occurred recently, several key areas where future earthquakes are anticipated. Thanks to satellite imagery and the dry terrain, the researchers can quantify the evolution of stresses in the region responsible for these future earthquakes in remarkable detail. They will use satellite radar observations to develop a detailed model of where the plate boundary fault is currently locked and where it is slowly creeping, suggesting reduced earthquake hazard. However, complicating these studies, a tenfold increase in local populations in the past two decades has increased the demand for water. This demand has been met by pumping water from a half dozen subsurface aquifers, but with catastrophic consequences. Lowered underground pressures have caused surface subsidence and open fissures in cities, leading in some cases to the demolition of schools and hospitals. These changes in subsurface pressure also have the potential to alter stresses on faults where earthquakes are anticipated. This project quantifies both the changing tectonic forces responsible for earthquakes, and the modification of these forces by unprecedented groundwater withdrawal in the region. In this project, satellite geodesy techniques, including satellite radar interferometry and Global Navigation Satellite System data, and creepmeters will be used to study the spatial and temporal distributions of ground deformation along the entire Chaman fault system during the time period from 2014 to 2023. The focus is on the following scientific targets: 1) quantify the surface deformation rates along the Chaman fault arising from interseismic coupling, fault creep, earthquakes, and ground subsidence due to groundwater extraction; 2) invert for the fault slip rates and locking depths of major faults in the Chaman fault system and identify the associated spatial distribution and temporal variation of interseismic strain accumulation and fault creep along both the Chaman and Ghazaband faults; 3) investigate the fundamental relationships between tectonic loading, time-variable fault creep rates, and earthquakes; 4) assess the hazards of regional earthquakes and hydrological changes based on estimates of fault slip rates and stressing influences from hydrological storage changes due to rapid depletion of regional aquifers. The researchers’ deformation quantification and modeling will provide new constraints on the potential for future earthquakes based on past earthquake occurrences and current hydrologic unloading.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在过去的五千万年里，地球深处的过程迫使印度次大陆与亚洲大陆发生碰撞。在北部，喜马拉雅山的高山和地震是这种持续碰撞的证据。卡拉奇和喀布尔之间 700 英里长的次大陆西部边缘有几条同样受到破坏性地震困扰的大断层，但研究较少。 尽管最近没有发生地震，但预计未来几个关键地区将发生地震。借助卫星图像和干燥地形，研究人员可以非常详细地量化导致未来地震的地区应力的演变。他们将利用卫星雷达观测来开发一个详细模型，显示板块边界断层目前锁定的位置以及缓慢蠕动的位置，这表明地震危险性降低。然而，使这些研究变得复杂的是，过去二十年当地人口增加了十倍，导致对水的需求增加。通过从六个地下含水层抽水来满足这一需求，但带来了灾难性的后果。地下压力降低导致城市地表沉降和开放性裂缝，在某些情况下导致学校和医院被拆除。地下压力的这些变化也有可能改变预计发生地震的断层上的应力。该项目量化了导致地震的不断变化的构造力，以及该地区前所未有的地下水抽取对这些力的改变。本项目将利用卫星大地测量技术，包括卫星雷达干涉测量和全球导航卫星系统数据以及蠕变仪，研究2014年至2023年期间整个查曼断层系地面变形的时空分布。重点实现以下科学目标：1）量化震间耦合、断层引起的沿查曼断层的地表变形速率。 由于抽取地下水而导致的蠕变、地震和地面沉降； 2）反演查曼断层系统中主要断层的断层滑移率和锁定深度，并识别沿查曼断层和加扎班德断层的震间应变积累和断层蠕变的相关空间分布和时间变化； 3）研究构造载荷、时变断层蠕变速率和地震之间的基本关系； 4）根据断层滑移率的估计和区域含水层快速枯竭导致的水文储量变化的应力影响，评估区域地震和水文变化的危害。研究人员的变形量化和建模将为基于过去地震发生和当前水文卸载的未来地震的可能性提供新的约束。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。