RAPID: Near-trench Deformation and Tsunami Runup from the Jan 3, 2010 Solomon Islands Earthquake

RAPID：2010 年 1 月 3 日所罗门群岛地震的近海沟变形和海啸上升

• 批准号: 1020239
• 负责人: Andrew Newman
• 金额: $ 2.44万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1020239&HistoricalAwards=false
• 关键词: RAPID; Near; trench; Deformation; Tsunami

On January 3, 2010 a moment magnitude, MW 7.1 earthquake occurred along a portion of the Solomon Islands, causing substantial strong shaking and triggering local landslides and a tsunami that impacted several of the islands, most notably Tetepare and Rendova. The event was likely triggered by, and occurred very near the southeastern terminus of the massive MW 8.1 earthquake of April 1, 2007, which itself caused a substantial local tsunami that devastated many coastal areas. This most recent event was unique in that it caused a notable tsunami that was identifiable on two ocean-bottom pressure sensors nearly 1000 km away, even though it was only a moderately large MW 7.1 event. Such disproportionate tsunami excitation is observed with moderately larger (MW 7.5-7.8) rare tsunami earthquakes, yet this exhibits only a modestly slow character.Two main possibilities are proposed to explain the tsunami excitation of the 2010 event: 1) The earthquake was a "partial tsunami earthquake" in that it ruptured both a fast and slow component, giving it a mostly normal energy-moment ratio (a now well established tsunami earthquake discriminant; or 2) Strong shaking from the event triggered a submarine landslide that generated the tsunami. It is likely that this event ruptured similarly to the 2007 event, with slip occurring primarily in discrete patches along the shallowest portion of the trench, much like slip observed in tsunami earthquakes. We will use the extreme proximity of coastal environments to the rupture area and trench to conduct a postseismic tsunami inundation and near-source geodetic deformation survey along the two most proximal islands to the event to identify the magnitude and distribution of both parameters. Geodetic measurements will include short-term static and kinematic GPS of uplifted and exposed coral communities and subsidence and submergence of anthropogenic structures. SAR scenes will also be evaluated for usable interferograms covering the affected islands. This information will be invaluable at assessing whether the coseismic slip alone was responsible for generating the observed tsunami, and will yield new insight into the potential for tsunami excitation from even low-magnitude 7 events occurring within the shallow trench. The tsunami run-up data will be modeled (in collaboration with researchers from NOAA) using the resultant coseismic interface slip model constrained from the combined geodetic techniques.This RAPID award was supported by the Geophysics, Marine Geology & Geophysics, and Geotechnical Engineering Programs.

2010 年 1 月 3 日，所罗门群岛部分地区发生里氏 7.1 级地震，造成强烈震动并引发当地山体滑坡和海啸，影响了几个岛屿，其中最引人注目的是特特帕雷和伦多瓦。该事件很可能是由 2007 年 4 月 1 日发生的 8.1 级大地震引发的，并且发生在该地震的东南端附近，该地震本身引发了一场严重的局部海啸，摧毁了许多沿海地区。最近的这次事件是独一无二的，因为它引发了一场值得注意的海啸，近 1000 公里外的两个海底压力传感器可以识别海啸，尽管这只是一个中等规模的 MW 7.1 事件。在中等较大（MW 7.5-7.8）的罕见海啸地震中观察到了这种不成比例的海啸激发，但这仅表现出适度缓慢的特征。提出了两种主要可能性来解释 2010 年事件的海啸激发：1）该地震是“部分海啸地震”，因为它同时破裂了快速和慢速部分，使其具有基本正常的能量力矩比（现在已确定的海啸地震）地震判别；或 2) 该事件引发的强烈震动引发了海底滑坡，从而引发了海啸。 这次事件的破裂很可能与 2007 年的事件类似，滑动主要发生在沿着海沟最浅部分的离散斑块中，很像在海啸地震中观察到的滑动。我们将利用沿海环境与破裂区和海沟的极端接近性，沿着距离事件最近的两个岛屿进行震后海啸淹没和近源大地变形调查，以确定这两个参数的震级和分布。大地测量将包括隆起和暴露的珊瑚群落以及人类结构的沉降和淹没的短期静态和运动 GPS。还将对 SAR 场景进行评估，以获得覆盖受影响岛屿的可用干涉图。这些信息对于评估同震滑动是否单独导致了所观测到的海啸的产生非常宝贵，并且将为浅海沟内发生的低震级 7 事件激发海啸的可能性提供新的见解。海啸助推数据将使用受组合大地测量技术限制的同震界面滑移模型（与 NOAA 的研究人员合作）进行建模。该 RAPID 奖项得到了地球物理学、海洋地质学和地球物理学以及岩土工程项目的支持。