Architecture of the Subduction to Strike-Slip Transition in New Zealand

新西兰俯冲到走滑过渡的结构

• 批准号: 1756075
• 负责人: Clifford Thurber
• 金额: $ 27.51万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-03-15 至 2024-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1756075&HistoricalAwards=false
• 关键词: Architecture; Subduction; Strike; Slip; Transition

In recent years, seismologists have come to recognize that many large earthquakes that occur involve slip on multiple faults. This phenomenon means that estimates of earthquake hazard based on the assumption that faults fail individually can underestimate the size of the largest possible earthquake in a region, and in turn the level of seismic hazard. The November 14, 2016 magnitude 7.8 Kaikoura earthquake in the northern South Island, New Zealand, stands out as one of the most complex earthquakes known, with rupture of the ground surface observed on more than 20 faults. The earthquake was followed by tens of thousands of aftershocks, and it also triggered a number of what are called "slow slip events" - fault slip occurring over days to months instead of seconds to minutes like most earthquakes. The Kaikoura earthquake is the latest in a series of damaging earthquakes in the northern part of the South Island in New Zealand that have struck in this decade. This project will examine several key questions related to the complicated geologic evolution of this region. This project will take advantage of data and results from a broad range of studies that have been carried out over the past two decades. It will also utilize seismic data from temporary arrays that were deployed to record aftershock and were operated, in part, with support of RAPID funding from NSF. The tasks of this project are to image the three-dimensional seismic velocity and attenuation structure, to relocate earthquakes that occurred in the region with high-precision, and to determine the fault slip geometry using the aftershock locations. This work will contribute to our understanding of how multiple-fault failure occurs in large earthquakes, thereby contributing to improving seismic hazard estimation. The work will be carried out in close collaboration with New Zealand scientists from GNS Science and Victoria University of Wellington. In addition, as part of the broader impacts, this project will mentor a female postdoctoral scholar.The November 14, 2016 Mw 7.8 Kaikoura earthquake in the northern South Island, New Zealand, stands out as one of the most complex seismic events known. Surface rupture has been mapped on at least 21 faults. Post-seismic slow slip events were triggered over a broad area, including substantial slip on the South Island megathrust underlying the activated crustal faults. The Kaikoura earthquake is the latest in a series of damaging earthquakes in the Canterbury and Marlborough regions of the South Island that have struck in this decade, starting with the Darfield and Christchurch earthquakes of 2010 and 2011, continuing with the Seddon and Lake Grassmere earthquakes of 2013, and culminating in the 2016 Kaikoura earthquake. We note that the Mw 7.1 Darfield earthquake was also a complex, multi-fault rupture.This project will examine several hypotheses related to the complex tectonics of this region of transition from subduction to strike-slip. The proposed study will take advantage of data and results from a broad range of studies that have been carried out in this region over the past two decades, and utilize data from temporary aftershock arrays supported in part by NSF through RAPID awards. The main analysis tools are seismic velocity and attenuation tomography that incorporate recent and planned methodological developments, high-precision earthquake relocation, and focal mechanism analysis. The work will be carried out in close collaboration with New Zealand scientists from GNS Science and Victoria University of Wellington and will engage a female postdoctoral scholar in the data analysis and interpretation.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.

近年来，地震学家逐渐认识到，发生的许多大地震都涉及多条断层上的滑动。这种现象意味着，基于断层单独失效的假设对地震危险性的估计可能低估了一个地区可能发生的最大地震的规模，进而低估了地震危险性的水平。2016年11月14日，新西兰南岛北部发生7.8级凯库拉地震，这是已知的最复杂的地震之一，在20多个断层上观察到地表破裂。地震之后发生了数以万计的余震，并引发了许多所谓的“慢滑事件”--断层滑动发生在几天到几个月的时间里，而不是像大多数地震那样发生在几秒到几分钟的时间里。凯库拉地震是新西兰南岛北部十年来发生的一系列破坏性地震中最新的一次。该项目将研究与该地区复杂的地质演化有关的几个关键问题。该项目将利用过去二十年来进行的广泛研究的数据和结果。它还将利用来自临时阵列的地震数据，这些阵列被部署来记录余震，并在一定程度上得到了国家科学基金会的快速资金支持。该项目的任务是对三维地震速度和衰减结构进行成像，高精度地重新定位发生在该地区的地震，并利用余震位置确定断层滑动几何形状。这项工作将有助于我们理解大地震中多断层破坏是如何发生的，从而有助于改进地震危险性估计。这项工作将与来自GNS Science和惠灵顿维多利亚大学的新西兰科学家密切合作进行。此外，作为更广泛影响的一部分，该项目将指导一名女性博士后学者。2016年11月14日，新西兰南岛北部7.8级凯库拉地震是已知的最复杂的地震事件之一。地表破裂已在至少21条断层上被绘制出来。地震后的慢滑事件是在大范围内触发的，包括在激活的地壳断裂下方的南岛巨型逆冲上的大幅滑动。凯库拉地震是南岛坎特伯雷和马尔伯勒地区十年来发生的一系列破坏性地震中最新的一次，从2010年和2011年的达菲尔德和克赖斯特彻奇地震开始，延续到2013年的塞登和格拉斯米尔湖地震，并在2016年的凯库拉地震中达到高潮。我们注意到，7.1兆瓦的达菲尔德地震也是一次复杂的、多断层的破裂。本项目将检验与该地区从俯冲到走滑过渡的复杂构造相关的几个假说。这项拟议的研究将利用过去20年来在该地区进行的广泛研究的数据和结果，并利用国家科学基金会通过快速奖励部分支持的临时余震阵列的数据。主要的分析工具是地震速度和衰减层析成像，其中包括最近和计划中的方法发展、高精度地震定位和震源机制分析。这项工作将与来自GNS Science和惠灵顿维多利亚大学的新西兰科学家密切合作，并将聘请一名女性博士后学者参与数据分析和解释。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Fracturing and pore-fluid distribution in the Marlborough region, New Zealand from body-wave tomography: Implications for regional understanding of the Kaikōura area

体波断层扫描新西兰马尔堡地区的压裂和孔隙流体分布：对凯库拉地区区域了解的启示

• DOI: 10.1016/j.epsl.2022.117666
• 发表时间: 2022
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Heath, Benjamin A.;Eberhart-Phillips, Donna;Lanza, Federica;Thurber, Clifford;Savage, Martha K.;Okada, Tomomi;Matsumoto, Satoshi;Iio, Yoshihisa;Bannister, Stephen
• 通讯作者: Bannister, Stephen

Spatial and temporal stress field changes in the focal area of the 2016 Kaikōura earthquake, New Zealand: A multi-fault process interpretation

2016年新西兰凯库拉地震震源区的时空应力场变化：多断层过程解释

• DOI: 10.1016/j.tecto.2022.229390
• 发表时间: 2022
• 期刊: Tectonophysics
• 影响因子: 2.9
• 作者: Matsuno, Miu;Tagami, Ayaka;Okada, Tomomi;Matsumoto, Satoshi;Kawamura, Yuta;Iio, Yoshihisa;Sato, Tadashi;Nakayama, Takashi;Hirahara, Satoshi;Bannister, Stephen
• 通讯作者: Bannister, Stephen