RAPID: GPS Observations of Co- and Post-seismic Deformation in the Argentine Puna from the 1 Apr 2014, Mw 8.2, Pisagua, Chile, Earthquake Sequence

RAPID：2014 年 4 月 1 日起阿根廷普纳地震同震和震后变形的 GPS 观测，Mw 8.2，智利比萨瓜地震序列

• 批准号: 1444233
• 负责人: Robert Smalley
• 金额: $ 3.39万
• 依托单位: University of Memphis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1444233&HistoricalAwards=false
• 关键词: RAPID; GPS; Observations; Co; Post

An unusual sequence of earthquakes began in the northern Chile subduction zone on March 16, 2014 with a 10-day long swarm of earthquakes that migrated to the north - a pattern similar to the swarm of earthquakes that presaged the 2011 magnitude 9.0 Tohoku Japan earthquake, which provoked concern in Chile because this megathrust zone last failed in a magnitude 8.8 earthquake in 1877 and is thought capable of producing a magnitude 9 earthquake again. So far, the largest event in the sequence is the April 1, 2014 magnitude 8.2 Pisagua, Chile earthquake. The ground deformation caused by this large earthquake will persist long after the earthquake and decay over a period of years. Measurements of the surface deformation during and after the event can provide important information about the properties of the Earth in the region, improve understanding of deformation processes, and aid in determining regions with a high likelihood of producing large aftershocks. Large dense GPS networks installed by U.S., German, French, Peruvian, and Chilean groups in Chile will record this deformation close to the earthquake epicenter but significant deformation is expected farther away in northwest Argentina. This rapid response project will install new GPS networks and collect data from existing GPS stations in the Argentine Puna Plateau to fully capture the ground motion associated with this event. These data will contribute to understanding the physics and hazard potential of large megathrust earthquakes in Chile and elsewhere, such as Cascadia, Alaska, and Japan.The April 1, 2014 Mw 8.2 Pisagua, Chile earthquake was the largest event in an unusual sequence of earthquakes, which began in the northern Chile subduction zone on March 16, 2014. Based on the USGS preliminary teleseismic and surface wave inversion, slip occurred along a 250 km along-strike and about 150 km down-dip section of the Chile megathrust that last failed in an M 8.8 earthquake in 1877. U.S., Chilean, Peruvian, German, and the French groups have built relatively dense continuously operating GPS (CGPS) and survey mode GPS (SGPS) station networks in this region, thus the near-field inter-, co- and post-seismic transient signals will be well observed in northern Chile. However, there will be significant co-seismic and post-seismic transient motion up to 700 km from the main event, incorporating nearly all of the Altiplano and at least much of eastern Cordillera in Bolivia, and the Puna of northwestern Argentina. Measuring the mid- and far-field co- and post-seismic signals in the Altiplano and beyond will be critical to any geodynamic modeling effort. In rapid response to the April 1, 2014 Mw 8.2 Pisagua, Chile earthquake, this project will install 4 new CGPS stations and retrieve data from 10 CGPS stations in the Argentine Puna Plateau. Data will be made immediately available to the international earth science community through the UNAVCO Facility Archive. These geodetic data could be important in determining regions with a high likelihood of producing large aftershocks and for hazard mitigation efforts because the largest aftershock (M 7.7 on April 3) was larger than expected, potentially indicating continued unusual activity with the neighboring segments thought to retain a large slip deficit.

2014 年 3 月 16 日，智利北部俯冲带开始发生一系列不寻常的地震，持续 10 天的地震群向北部迁移，这种模式类似于预示 2011 年日本东北地区 9.0 级地震的地震群。这引起了智利的关注，因为这个巨型逆冲断层带上次在 1877 年发生的 8.8 级地震中失败，并且被认为能够产生震级9级地震又来了迄今为止，该序列中最大的事件是 2014 年 4 月 1 日智利皮萨瓜发生的里氏 8.2 级地震。这次大地震造成的地面变形将在震后持续很长时间，并在几年内衰减。事件期间和之后的地表变形测量可以提供有关该地区地球特性的重要信息，增进对变形过程的了解，并有助于确定极有可能产生大型余震的区域。美国、德国、法国、秘鲁和智利团体在智利安装的大型密集GPS网络将记录震中附近的这种变形，但预计在阿根廷西北部更远的地方也会出现显着变形。该快速响应项目将安装新的 GPS 网络，并从阿根廷普纳高原现有的 GPS 站收集数据，以充分捕捉与该事件相关的地面运动。这些数据将有助于了解智利和卡斯卡迪亚、阿拉斯加和日本等其他地方发生的大型逆冲地震的物理性质和潜在危险。2014 年 4 月 1 日智利皮萨瓜发生的 8.2 级地震是一系列不寻常地震中最大的一次地震2014年3月16日开始于智利北部俯冲带。根据USGS初步远震和面波反演，沿250公里发生了滑动智利巨型逆冲断层的沿走向和约 150 公里下倾部分，最后一次在 1877 年的 8.8 级地震中失败。美国、智利、秘鲁、德国和法国团体已经建立了相对密集的连续运行 GPS (CGPS) 和勘测模式GPS（SGPS）站网在该地区，因此在智利北部可以很好地观测到近场震间、同震和震后瞬变信号。然而，距主事件700公里范围内将发生显着的同震和震后瞬态运动，包括几乎整个高原和玻利维亚东部科迪勒拉山脉的大部分地区以及阿根廷西北部的普纳。测量高原及其他地区的中远场同震和震后信号对于任何地球动力学建模工作都至关重要。为了快速应对2014年4月1日智利皮萨瓜Mw 8.2地震，该项目将安装4个新的CGPS站，并从阿根廷普纳高原的10个CGPS站检索数据。数据将通过 UNAVCO 设施档案立即提供给国际地球科学界。这些大地测量数据对于确定极有可能发生大型余震的区域和减灾工作非常重要，因为最大的余震（4 月 3 日的 7.7 级余震）比预期的要大，这可能表明邻近地区仍存在异常活动较大的滑差赤字。