Dominant seismic noise sources in the Southern Ocean and West Pacific, 2000–2012, recorded at the Warramunga Seismic Array, Australia

Abstract

Seismic noise is important in determining Earth structure and also provides an insight into ocean wave patterns and long-term trends in storm activity and global climate. We present a long-duration study of seismic noise focused on the Southern Ocean using recordings from the Warramunga Seismic Array, Northern Territory, Australia. Using high-resolution analysis, we determine the seismic slowness and back azimuth of observed seismic noise, microseisms, at hourly intervals through over a decade (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012). We identify three dominant sources of body wave (P) noise in the Southern Ocean which we interpret to originate from a South Atlantic source propagating as PP waves, and Kerguelen Island and Philippine Sea sources propagating as P waves. We also identify surface waves from around the Australian coast. All sources show distinct seasonality and a low, but discernable, interannual variability.

Ambient Seismic Source Inversion in a Heterogeneous Earth: Theory and Application to the Earth's Hum

“…Previously developed localization methods for ambient sources include spectral analysis (e.g., Anthony et al, ; Bromirski, ; Bromirski & Duennebier, ), polarization analysis (e.g., Chevrot et al, ; Schimmel et al, ; Schulte‐Pelkum et al, ), cross correlation‐based imaging (e.g., Ermert et al, ; Stehly et al, ; Tian & Ritzwoller, ; Yang & Ritzwoller, ), beamforming (e.g., Behr et al, ; Gal et al, ; Gerstoft & Tanimoto, ; Juretzek & Hadziioannou, ; Kurrle & Widmer‐Schnidrig, ; Landès et al, ; Reading et al, ; Rhie & Romanowicz, ), migration of cross‐correlation signals (Brzak et al, ; Dales et al, ; Retailleau et al, ), grid searches for fitting particular observables (Gaudot et al, ; Rhie & Romanowicz, ; Shapiro et al, ), and inversion based on simplified plane‐wave models of noise cross correlations (Harmon et al, ; Lehujeur et al, ; Sadeghisorkhani et al, ; Yao & van der Hilst, ). Nishida and Fukao () inverted for the seasonal source of the Earth's hum using a model of cross correlations based on normal modes and a spherically symmetric Earth model.…”

Matched Field Processing of Three‐Component Seismic Array Data Applied to Rayleigh and Love Microseisms

“…Microseism body waves have received a great deal of attention (e.g., Boue et al, ; Capon, ; Euler et al, ; Farra et al, ; Gal et al, ; Gerstoft et al, ; Gualtieri et al, ; Haubrich & McCamy, ; Koper et al, , ; Lacoss et al, ; Landès et al, ; Liu et al, ; Neale et al, ; Nishida & Takagi, ; Obrebski et al, ; Pyle et al, ; Reading et al, ; Toksöz & Lacoss, ; Traer et al, ; Zhang et al, , ) which can be attributed to the fact that back azimuth and velocity obtained from plane wave beamforming provide information on their spatial source region. On the other hand, the analysis of microseism surface waves (e.g., Behr et al, ; Bromirski & Duennebier, ; Bromirski et al, , ; Brooks et al, ; Cessaro, ; Chevrot et al, ; Friedrich et al, ; Gal et al, ; Juretzek & Hadziioannou, ; Kedar et al, ; Obrebski et al, ; Roux et al, ; Schulte‐Pelkum et al, ; Stehly et al, ) for constraining their source regions has experienced limited application.…”

Sources of secondary microseisms in the Indian Ocean

“…Koper & De Foy 2008;Sheen 2014) and the Southern oceans (e.g. Reading et al 2014). The motivation of this work is therefore to improve our knowledge of the noise sources in the Indian Ocean.…”