Collaborative Research: Postseismic deformation for the Izmit-Duzce, Turkey earthquakes: Implications for the mechanics of the earthquake cycle and rheology of the continent

合作研究：土耳其伊兹米特-迪兹杰地震的震后变形：对地震周期力学和大陆流变学的影响

• 批准号: 1045487
• 负责人: Robert Reilinger
• 金额: $ 6.5万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1045487&HistoricalAwards=false
• 关键词: Collaborative; Research; Postseismic; deformation; Izmit

The 1999 Izmit, Turkey earthquake sequence (M=7.5, August, Gulcuk and M=7.1, November, Duzce earthquakes) occurred within a pre-existing GPS network making it one of the most geodetically well observed seismic events on a major continental strike slip fault. Well-defined pre-earthquake strain accumulation, coseismic motions (reaching ~2 m), short-term (days - months) postseismic afterslip, and longer-term (years - 10 years) postseismic relaxation are all well imaged by geodetic observations. In addition, the earthquake appears to have altered the character of interseismic motions in unexpected ways (i.e., not easily ascribed to standard postseismic processes) as far as 200 - 300 km from the coseismic fault. As such, this event is providing fundamental constraints on the earthquake deformation cycle (inter-, pre-, co-, and postseismic) with direct implications for forecasting future earthquakes on this fault system, and by analogy for understanding the dynamics of similar strike slip faults, including the San Andreas Fault in California.The 1999 sequence occurred along the eastern segment of a seismic gap that extends south of Istanbul across the Sea of Marmara, raising serious concerns about a future earthquake on the western Marmara segment that could have devastating effects on this vulnerable mega-city ( 20 million people). Uncertainty persists about the possible magnitude of future earthquakes in the Marmara Sea, as well as how strain is transferred from the Izmit segment to the Main Marmara Fault (MMF) within the Sea (i.e., the geometry, degree of locking, slip rate on the connecting fault). The Princes Islands are located within the Marmara south of Istanbul and approach within less than 5 km of the Izmit-Marmara connecting fault segment. Two islands (Sivriada and Büyükada) located very near the connecting segment have been selected for ICDP borehole sites (GFZ, Germany are leading this ICDP initiative). In cooperation with this work, we are focusing our initial efforts on installing GPS stations at both borehole sites. Data from these stations will be downloaded by our Turkish partners at the Marmara Research Center and by UNAVCO. Over three years, these GPS observations will provide improved constraints on the dip, locking depth, and present-day rate of strain accumulation on this fault segment. These anticipated results together with analyses of postseismic deformation throughout the Marmara region, promise to provide improved understanding of the earthquake deformation cycle, and accordingly, estimates of the timing and magnitude of future earthquakes in the Sea of Marmara.This project is funded by the Geophysics and Tectonics Programs of NSF.

1999年土耳其伊兹米特地震序列（古尔丘克8月M=7.5，杜兹采11月M=7.1）发生在一个预先存在的GPS网络内，使其成为在一个主要大陆走滑断层上测地观测最好的地震事件之一。 定义明确的震前应变积累，同震运动（达到~2米），短期（天-月）震后余震，和长期（年- 10年）震后松弛都很好地成像大地测量观测。 此外，地震似乎以意想不到的方式改变了震间运动的特征（即，不容易归因于标准震后过程），距离同震断层200 - 300 km。 因此，这一事件对地震变形周期提供了根本性的限制（震间、震前、同震和震后），对预测该断层系统未来的地震有直接影响，并通过类比了解类似走滑断层的动力学，包括加州的圣安德烈亚斯断层。1999年的地震序列发生在沿着地震空区的东段，该空区延伸到伊斯坦布尔以南，2010年，在马尔马拉海附近发生了一次地震，令人严重关切的是，马尔马拉海西段未来可能发生地震，对这一脆弱的特大城市（2 000万人口）造成毁灭性影响。 关于马尔马拉海未来地震的可能震级，以及应变如何从伊兹米特段转移到海中的主马尔马拉断层（MMF）（即，几何形状、锁定程度、连接断层上的滑动速率）。王子群岛位于伊斯坦布尔南部的马尔马拉内，距离伊兹米特-马尔马拉连接断层段不到5公里。 已选定非常靠近连接段的两个岛屿（Sivriada和Büyükada）作为综合社区发展项目的钻孔地点（德国的GFZ正在领导这一综合社区发展项目倡议）。 在这项工作的合作中，我们正在集中精力在两个钻孔地点安装全球定位系统站。 我们在马尔马拉研究中心的土耳其合作伙伴和联合国志愿人员组织将下载这些台站的数据。在三年多的时间里，这些GPS观测将提供更好的限制倾角，锁定深度，和现今的应变积累率在这个断层段。 这些预期的结果与整个马尔马拉地区的震后变形分析一起，有望提供对地震变形周期的更好理解，并因此估计马尔马拉海未来地震的时间和震级。