Post-Katrina re-survey of key geodetic benchmarks in coastal Louisiana

卡特里娜飓风过后对路易斯安那州沿海主要大地测量基准的重新调查

• 批准号: 0609768
• 负责人: Roy Dokka
• 金额: $ 8.58万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-15 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0609768&HistoricalAwards=false
• 关键词: Post; Katrina; re; survey; key

0609768DokkaFunds from this Small Grant for Exploratory Research (SGER) support a collaborative effort by PIs Tim Dixon (Miami - RSMAS) and Roy Dokka (LSU) to conduct GPS resurveys of existing campaign benchmarks in the New Orleans area and to establish 10 additional continuously operated and permanently monumented GPS stations in the region. The recent tragic flooding of New Orleans, Louisiana, associated with Hurricane Katrina on August 29, 2005, emphasizes the hazardous setting of this urban area. Preliminary GPS and leveling data collected by the PIs suggest that New Orleans is subsiding rapidly because it is located in the hanging wall of an active listric normal fault system (the Michoud fault) that accommodates southward motion of the Mississippi delta into the Gulf of Mexico. Averaged over the last decade, southward motion of this upper crustal block relative to the stable interior of North America occurs at a rate of 2.3 plus or minus 1.7 mm/yr. Leveling data suggest that the rate of motion may have been higher in the recent past. The average subsidence rate for GPS sites located on the delta is 5.2 plus or minus 2.3 mm/yr relative to Earths's center of mass, or about 7 mm/yr relative to mean sea level. Movement of the delta block on the listric fault appear to be facilitated by underlying salt horizons that have been imaged by seismic reflection campaigns. These horizons accommodate deformation via ductile flow at low temperatures, hence there is little or no seismicity associated with faulting. The proposed additional GPS observations will help to confirm the proposed Michoud fault dynamics and to test the possibility that ground deformation accelerated following Katrina-related water mass loading. Data from this project will provide critical background tectonic framework to guide policy makers during the rebuilding of New Orleans.***

0609768 Dokka探索性研究小额赠款（SGER）中的资金支持PI Tim狄克逊（迈阿密- RSMAS）和Roy Dokka（路易斯安那州立大学）的合作努力，对新奥尔良地区现有的战役基准进行GPS重新调查，并在该地区建立10个额外的连续运行和永久纪念的GPS站。 2005年8月29日，路易斯安那州新奥尔良市发生了与卡特里娜飓风有关的悲惨洪水，突出了这一城市地区的危险环境。 初步GPS和由PI收集的水准测量数据表明，新奥尔良正在迅速下沉，因为它位于一个活跃的铲状正断层系统（Michoud断层）的上盘，该断层系统可容纳密西西比三角洲向南运动进入墨西哥湾。 在过去十年中，该上地壳块体相对于北美稳定内部的向南运动的平均速率为2.3 ± 1.7毫米/年。水准测量数据表明，最近的运动速率可能更高。位于三角洲上的GPS站点的平均沉降速率为5.2 ± 2.3毫米/年，相对于地球质心，或相对于平均海平面约7毫米/年。三角洲块的运动在铲状断层似乎是由下伏盐层，已被成像的地震反射运动促进。这些层位通过低温下的韧性流动适应变形，因此很少或没有与断层有关的地震活动。 拟议的额外GPS观测将有助于确认拟议的Michoud断层动力学，并测试卡特里娜相关水团加载后地面变形加速的可能性。 该项目的数据将提供关键的背景构造框架，以指导新奥尔良重建期间的政策制定者。