Ground Truth Events: Assessing the Capability of Infrasound Networks Using High Resolution Data Analyses

Abstract

The purpose of building and maintaining an infrasound network is to be able to detect, identify, and locate low-frequency atmospheric pressure disturbances. In order to assess the capability of such a network, and to recognise potential weaknesses, the system must be tested using signals from well understood sources. Events which generate such signals are referred to as ground truth and are defined as being events for which the source location, origin time and acoustic generation mechanism are known through independent means. In ideal circumstances, a measure of the source magnitude should also be ascertained, and parameters influencing the acoustic radiation pattern such as local terrain and ground cover should be identified. Similar to seismic ground truth parameters (e.g., Bondar et al. 2004a), the infrasound ground truth parameters are associated with only the source. Meteorological parameters which influence the propagation of the acoustic waves (e.g., temperature and wind) are not considered ground truth, and it is often the accuracy of these atmospheric parameters that we wish to test using signals from ground truth events.