Magmatic system structure and seismicity of the Three Sisters volcanic complex

三姐妹火山杂岩岩浆系统结构与地震活动

• 批准号: 2342525
• 负责人: Brandon Schmandt
• 金额: $ 39.97万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-06-01 至 2027-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2342525&HistoricalAwards=false
• 关键词: Magmatic; system; structure; seismicity; Three

This project investigates the Three Sisters volcanic complex in central Oregon. It will use seismic observations and methods to advance understanding of volcanic hazards and the fundamental processes that create different types of volcanoes and magma types. This volcanic system is active, and the presence of nearby population centers means the Three Sisters is classified as a Very High Threat volcanic system for the U.S. The Three Sisters volcanic complex includes a wide variety of volcanic structures and geologically young lavas (about 2,000 years old). Additionally, about two decades of satellite data show that areas near the volcanoes are deforming due to inflation under the surface. Existing data are scarce partly because the immediate vicinity of the volcanoes is a difficult to access and federally protected Wilderness. This project will add observations in these areas by using small temporary seismic instruments, that can be transported on foot and do not require digging, to address both the accessibility challenges and the need for minimal impact. Combining the new temporary seismic data with modern imaging and earthquake detection methods, the researchers will gain a systematic view of subsurface structures. This will assist in more rigorously understanding the record of prior eruptions and ongoing monitoring of deformation. The seismic data collection and analysis will engage students from multiple institutions and personnel from regional hazard monitoring agencies to promote professional training and communication to stakeholders.The Three Sisters volcanic complex is classified by a U.S. Geologic Survey report as a Very High Threat system, with geodetic evidence for ongoing surface deformation, lava flows as young as about 1,600 years, and Holocene eruptions of compositions ranging from basaltic andesite to rhyolite. Yet, there is little knowledge of the 3-D distribution of middle to upper crustal magma storage and microseismicity beneath this multi-vent volcanic complex located within the High Cascades graben. Observational seismology has been limited by the need for minimal impact in a large federal Wilderness. The project will deploy an array of low-impact nodal seismometers to provide the first local imaging of the Three Sisters magmatic system. Analysis of the data will advance understanding of how magma reservoir structure in multi-vent systems is linked to spatial variations in edifice construction and erupted compositions, with dominantly basaltic andesite in the northern part of the volcanic complex transitioning to more prevalent rhyolite eruptions at the southern end. Seismic imaging with the new temporary network data will begin with relatively conventional ambient noise surface wave tomography and then push the boundaries of temporary nodal array imaging by applying anisotropic adjoint tomography. The influences of edifice topography and radial anisotropy on magma reservoir imaging will be tested with numerical 3-D wave propagation and inversion methods. The new data will also be used to scrutinize microseismic activity and conduct receiver function imaging of localized interfaces, which could better define interactions between tectonic and magmatic deformation structures.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.

该项目调查了俄勒冈州中部的三姐妹火山综合体。它将使用地震观测和方法来提高对火山危害的了解以及创造不同类型的火山和岩浆类型的基本过程。该火山系统是活跃的，附近人口中心的存在意味着这三个姐妹被归类为美国三姐妹的火山系统非常高的威胁火山系统，其中包括各种各样的火山结构和地质年轻的熔岩（约200，000年历史） ）。此外，大约二十年的卫星数据表明，由于表面下方的通货膨胀，火山附近的区域正在变形。现有数据之所以稀缺，是因为火山的直接附近很难进入和受联邦保护的荒野。该项目将通过使用小型临时地震仪器在这些区域中增加观察结果，这些仪器可以步行运输并且不需要挖掘，以应对可及性挑战和对最小影响的需求。研究人员将新的临时地震数据与现代成像和地震检测方法相结合，将获得地下结构的系统观点。这将有助于更严格地理解先前喷发的记录和对变形的持续监测。地震数据收集和分析将吸引来自地区危害监测机构的多个机构和人员的学生，以促进与利益相关者的专业培训和沟通。三姐妹火山综合体由美国地质调查报告归类为非常高的威胁系统，将持续的表面变形的证据，熔岩的流量大约1,600年，以及从玄武岩安山岩到流纹岩的全新世发射。然而，几乎不了解在高层cascades graben内的这个多源火山综合体下方的中层岩浆储存和微震震的3-D分布。观察性地震学受到对大型联邦荒野的影响最小的影响的限制。该项目将部署一系列低影响的节点地震仪，以提供三姐妹岩浆系统的第一个本地成像。数据的分析将进一步了解多通风系统中的岩浆储层结构如何与建筑物的空间变化和爆发的组合物有关，火山络合物北部的玄武岩和质量占据了更为普遍的节奏性的玄武岩和岩石的影响。结尾。使用新的临时网络数据的地震成像将从相对常规的环境噪声表面波层析成像开始，然后通过应用各向异性的伴随层析成像来推动临时淋巴结阵列成像的边界。大厦地形和径向各向异性对岩浆储层成像的影响将通过数值3-D波传播和反转方法测试。新数据还将用于仔细检查微观震动活动并进行局部界面的接收器功能成像，这可以更好地定义构造和岩浆变形结构之间的相互作用。该奖项反映了NSF的法定任务，并被认为是通过使用基金会的评估来获得的支持，智力优点和更广泛的影响审查标准。