POSTSEISMIC GPS SURVEY, MODELING, AND EDUCATION FOLLOWING THE M7.0 JANUARY 12, 2010 EARTHQUAKE IN HAITI

2010年1月12日，海地太子港地区发生里氏7级地震，造成约23万人死亡，150多万人无家可归，全国经济损失达120%。摧毁了这个拥有300万人口的地区的大部分政府、技术和教育基础设施。尽管地球科学界警告说，海地有发生地震的高风险，但这个国家发现自己毫无准备。历史上的地震活动表明，这次地震可能是一个新的大型事件周期的开始，因此必须了解未来几年地震危害最大的地方，并为海地人民做好应对这种可能性的准备。为此，我们将测量震后变形，以约束应力传递的数值模型，并开发一套针对海地的地震教育课程，供海地高中使用。具体而言，该项目将(1)利用现有的连续GPS站和我们在1月地震后立即安装和观测的调查站点的组合测量三维地震后变形；(2)利用这些约束条件对地震后变形有限元模型进行验证，推断余震、孔弹性回弹和粘弹性松弛三种主要震后机制的相对贡献和深度分布；(3)利用得到的有限元模型计算未来几年区域断层库仑应力的演化，以确定当前加载速度最快的分段。1月份的地震是自大地测量时代以来发生在北加勒比板块的第一次大地震，因此为利用震后观测来探索该地区下地壳和上地幔的流变特性提供了一个关键机会。这项工作对于了解该板块边界的逆压是如何在深度上进行调节的至关重要，更重要的是，了解地震后的过程如何改变该地区其他活动断层的应力场。因此，这项工作将有助于提高我们对1月12日海地地震相关危害的理解，并有助于确定该断层系统即将发生其他大地震的可能性。该项目启动了海地非常需要的地球科学能力建设工作，包括培训海地合作者使用现代空间大地测量技术和教育海地？年代年轻。在进行GPS工作的同时，我们将访问途经城镇的海地高中，讨论海地的构造和地震危险。此外，我们将与美国和海地的高中教师和学生合作，与无国界教师组织合作，为海地高中编写地震教育课程。课程将侧重于区域构造，地震危害，准备和规划工作具体到海地，以创造一个持久的遗产地震教育。

On January 12, 2010 a Mw7 earthquake struck the Port-au-Prince region of Haiti, killing an estimated 230,000 people, leaving more than 1.5 million homeless, costing 120% of the country?s GDP, and destroying most governmental, technical, and educational infrastructure throughout this region of 3 million people. Despite warnings from the geoscience community that Haiti was at high risk for an earthquake, the country found itself unprepared. With historical seismicity indicating that this earthquake may be the beginning of a new cycle of large events, it is imperative to understand where seismic hazards are greatest in the years to come, and to prepare the people of Haiti for this eventuality. To this end we will measure postseismic deformation to constrain numerical models of stress transfer and develop a Haiti-specific earthquake education curriculum for use in Haitian high schools. Specifically, this project will (1) measure 3-dimensional postseismic deformation using a combination of existing continuous GPS stations and survey sites that we installed and observed immediately following the January earthquake; (2) use these constraints to validate finite element models of postseismic deformation and infer the relative contributions and depth distributions of the three main postseismic mechanisms: afterslip, poroelastic rebound, and viscoelastic relaxation; and (3) use the resulting finite element models to calculate the evolution of Coulomb stress on regional faults in the years to come to determine which segments are currently being loaded at the fastest rates. The January earthquake is the first large event to occur in the northern Caribbean plate within the geodetic age, and thus provides a key opportunity to use postseismic observations to explore the rheological properties of the lower crust and upper mantle in this region. This work is critical to understanding how transpression at this plate boundary is accommodated at depth, and more imperatively, how postseismic processes are currently working to change the stress field on other active faults in the region. Thus, this work will help to improve improving our understanding of the hazards associated with earthquakes in Haiti following the January 12 event and help define the likelihood that other large earthquakes may be impending along that fault system. The project initiates a capacity building effort in geosciences that is so much needed in Haiti, including the training of Haitian collaborators in the use of modern space geodetic techniques and the education of Haiti?s young. While conducting our GPS work, we will visit Haitian high schools in the towns we pass through to discuss the tectonics and earthquake hazards of Haiti. In addition, we will work with US and Haitian high school teachers and students, in collaboration with Teachers Without Borders to develop an earthquake education curriculum for use in Haitian high schools. The curriculum will focus on regional tectonics, earthquake hazards, and preparedness and planning efforts specific to Haiti in order to create a lasting legacy of earthquake education.