Geodetic observations at the early stage of subduction zone seismic cycle: towards complete seismic cycle coverage

俯冲带地震周期早期大地测量观测：走向完整的地震周期覆盖

• 批准号: 1345100
• 负责人: Timothy Dixon
• 金额: $ 26万
• 依托单位: University of South Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1345100&HistoricalAwards=false
• 关键词: Geodetic; observations; early; stage; subduction

Subduction zones such as those along the Pacific ?Ring of Fire? produce Earth?s largest and most destructive earthquakes, and most tsunamis. The giant earthquakes and tsunamis of 2004 (Sumatra) and 2011 (Japan) were wake up calls that our ability to estimate future earthquake magnitude remains weak. Measurement of strain accumulation in the vicinity of subduction zones, as is now possible with high precision GPS units, has the potential to forecast the location and size of future earthquakes. The coastal Nicoya Peninsula of Costa Rica lies close to the trench (70 km), allowing observations directly over the seismogenic zone. Here I propose to upgrade and operate a continuous high precision GPS network in the Nicoya Peninsula, and use the resulting data to investigate a number of questions related to seismic and tsunami processes in the subduction zone environment. In principle these kind of measurements could provide predictive capability in terms of location and size of future earthquakes and perhaps tsunamis (timing would still presumably be unknown). Northern Costa Rica is characterized by fast (~8 cm/yr) subduction and a short (50?60 year) earthquake cycle, producing frequent large (M7.5) earthquakes including events in 1853, 1900, 1950 (M 7.7) and most recently September 5, 2012 (M 7.6). Previous NSF-funded studies in this region have defined the regional tectonics and quantified a number of key seismogenic parameters at the late stage of the seismic cycle, including the pattern of interseismic strain accumulation and microseismicity, and the nature and timing of slow slip events (SSE). The 2012 earthquake gives us a chance to investigate these processes at the beginning of a seismic cycle, providing the scientific community an incredible opportunity to characterize a complete seismic cycle. All data generated by the Nicoya C-GPS network are made publicly available through UNAVCO, and analyzed products (e.g, coseismic and slow slip offsets) are available on my website (http://labs.cas.usf.edu/geodesy/) to assist researchers who are unfamiliar with the details of GPS processing use the data for earthquake research.

比如太平洋沿岸的俯冲带？火山带？地球产生?美国最大和最具破坏性的地震，以及大多数海啸。2004年（苏门答腊）和2011年（日本）的大地震和海啸提醒我们，我们估计未来地震震级的能力仍然很弱。对俯冲带附近的应变积累的测量，如现在高精度GPS装置所可能的那样，有可能预测未来地震的位置和大小。哥斯达黎加沿海的尼科亚半岛靠近海沟（70公里），可以直接在发震区进行观测。在这里，我建议在尼科亚半岛升级和运行一个连续的高精度GPS网络，并利用得到的数据来研究俯冲带环境中地震和海啸过程的一些相关问题。原则上，这些测量可以提供预测未来地震和海啸的位置和大小的能力（时间可能仍然未知）。哥斯达黎加北部的特点是俯冲速度快（~ 8cm /年），俯冲时间短(50？60年)的地震周期，频繁发生大地震（7.5级），包括1853年、1900年、1950年（7.7级）和最近的2012年9月5日（7.6级）。在此之前，nsf资助的研究已经确定了该地区的区域构造，并量化了地震周期后期的一些关键孕震参数，包括震间应变积累和微震活动模式，以及慢滑事件（SSE）的性质和时间。2012年的地震让我们有机会在地震周期开始时研究这些过程，为科学界提供了一个难以置信的机会来描述一个完整的地震周期。Nicoya C-GPS网络生成的所有数据都通过联合国维和行动处公开提供，并在我的网站（http://labs.cas.usf.edu/geodesy/）上提供分析过的产品（例如同震和慢滑偏移），以帮助不熟悉GPS处理细节的研究人员使用这些数据进行地震研究。