Infrasonic and Gravity Wave Studies in the Central United States

美国中部的次声波和重力波研究可移动阵列（TA）的地震仪不仅直接测量由于地球固体内部的源引起的地面运动，它们还间接提供有关影响地面运动的其他现象的有价值的信息，例如大气次声波和重力波。 最近，电讯管理局的400个地点全部加装了气压计和次声传声器。 “地球镜”科学计划包括“冰冻圈、水圈和大气层”作为科学目标。具体而言，“次声场的研究允许对大气结构进行新的深海探测，并促进对火山、海洋和其他次声源的定量表征。“最近的研究表明，无论次声信号是由地震仪还是麦克风记录的，TA站点的密度都允许人们准确地定位次声源。 该项目是在2007年至2008年美国西部地震阵列记录的900多次次声压力扰动或“天震”的探测和定位方面的地震资助工作的基础上进行的。方法正在改进并应用于地震，美国中部的美国声学阵列。以前未被发现的天震正在被确定为是在TA传播的重力波的来源。 该项目的目标是确定从2009年1月到2012年3月这些源的发生、波形结构和传播统计数据。 这些事件与大气现象如龙卷风和阵风锋之间的相关性正在研究中。 这项工作产生了两个新的次声和重力波事件位置，到达特性和波形数据库。 该项目还从几个高质量的事件中详细说明了次声到达分支。

Infrasonic and Gravity Wave Studies in the Central United StatesSeismometers of the Transportable Array (TA) not only directly measure ground motion due to sources within the Earth's solid interior, they also indirectly provide valuable information about other phenomena that affect ground motion, such as atmospheric infrasound and gravity waves. Recently all 400 sites of the TA were retrofitted with barometers and infrasonic microphones. The Earthscope Science Plan includes as a scientific target the "cryosphere, hydrosphere, and atmosphere". Specifically, "studies of the infrasonic field allow for novel deep sounding of atmospheric structure and facilitate quantitative characterization of volcanic, oceanic, and other infrasonic sources." It has been recently shown that the density of TA sites permits one to accurately locate infrasonic sources, regardless if the infrasonic signals are registered by seismometers or microphones. This project is expanding upon previous Earthscope-funded work on the detection and location of more than 900 infrasonic pressure disturbances, or "skyquakes", that were registered by the seismic USArray during 2007-08 in the western U.S. Specifically, methods are being improved and applied to the seismo-acoustic USArray in the central U.S. Previously undetected skyquakes are being identified as are sources of gravity waves that propagate across the TA. The goals of this project are to identify the occurrence, waveform structure, and propagation statistics of these sources from 01/2009 through 03/2012. Correlations are being made between these events and atmospheric phenomena such as tornadoes and gust fronts. This work is resulting in two new databases of infrasonic and gravity wave event locations, arrival characteristics, and waveforms. The project is also illuminating infrasonic arrival branches in fine detail from several high-quality events.