Distribution of Rayleigh Wave Microseisms Constrained by Multiple Seismic Arrays

Abstract

Microseisms are the most energetic signals of Earth's ambient noise field. Locating the sources of microseisms helps us to understand arrivals on noise cross‐correlation functions (NCFs) and the asymmetric amplitude of Rayleigh waves on the positive and negative parts of the NCFs. Using a dense broadband seismic array in eastern China, we investigated temporal and spatial characteristics of Rayleigh wave microseisms in the frequency range of 45–155 mHz by conducting beamforming and Rayleigh wave amplitude‐azimuth variation analyses. Seasonal variations of incident direction are clearly observable at the primary microseisms frequency band (45–95 mHz) but are less prominent at the secondary microseisms frequency band (95–155 mHz). The beamforming and amplitude‐azimuth variation analyses also indicated that microseisms arriving at the array are dominantly from five back azimuthal bands. To locate the source areas of the observed microseisms, we combined noise data from two additional arrays in southern California and employed a multi‐array beamforming technique to constrain plausible microseisms' source areas. We found that microseisms of the five azimuthal bands were excited at the Southern Ocean, western coast of Europe, coastal areas of the North Pacific Ocean, the Kerguelen Islands in the southern Indian Ocean, and the Polynesia islands in the South Pacific Ocean, respectively.

Achievements and Prospects of Global Broadband Seismographic Networks After 30 Years of Continuous Geophysical Observations

“…With continued developments in seismic instrumentation, additional arrays of 3‐component, broadband seismometers have been emplaced across the globe during the last 30 years and have driven advances in understanding fault rupture dynamics (e.g., Ishii et al., 2005), improved resolution in seismic mantle imaging (e.g., Schmandt & Lin, 2014), and helped reveal the global source regions of ambient noise (e.g., Friedrich et al., 1998; Z. Wang et al., 2021). However, seismic arrays have been, and are today, overwhelmingly located in the northern hemisphere and long periods of operation are often required to both calibrate them and to attain maximal resolution in seismic imaging (Schweitzer et al., 2012).…”

“…With continued developments in seismic instrumentation, additional arrays of 3-component, broadband seismometers have been emplaced across the globe during the last 30 years and have driven advances in understanding fault rupture dynamics (e.g., Ishii et al, 2005), improved resolution in seismic mantle imaging (e.g., Schmandt & Lin, 2014), and helped reveal the global source regions of ambient noise (e.g., Friedrich et al, 1998;Z. Wang et al, 2021).…”

Sharp Changes of Crustal Seismic Anisotropy Across the Central Tanlu Fault Zone in East China

“…In this study, we used waveform data of a temporary dense broadband array installed across the Weifang segment of the Tanlu Fault (hereinafter referred to as TLarray). The array was deployed between August of 2017 and July of 2018 and comprised 31 Nanometrics trillium 120 posthole sensors and centaur digitizers with a station spacing of ∼5–30 km (Wang et al., 2021). We also used data from another linear array with 51 broadband stations in the southern part of the study area.…”

Exploring the Deep Ocean Single‐Frequency Microseisms Southwest of Japan in Northern Philippine Sea

“…(2020) derived the sources of SFMs possibly dwell over wide areas of the Atlantic Ocean where the water depth may be up to 2,000 m based on NCFs of data recorded from the east coast of America; and Wang et al. (2021) identified a total of five SFMs sources including the deep ocean area in Southern ocean and northern Pacific ocean. In addition, direct observations on ocean bottom seismometers (OBSs) also clearly detected SFMs in deep ocean (e.g., Guo, Xue, et al., 2020; Stephen et al., 2003; Tian & Ritzwoller, 2015; Yang et al., 2012).…”

“…While shallow water are well accepted source regions for SFMs, a few studies located the sources of SFMs observed in deep ocean: for example, Stehly et al (2006) located the sources of SFMs in the northern Atlantic and northern Pacific during the winter and in the Indian Ocean and southern Pacific during the summer by analyzing data recorded in eastern United States, Europe and Tanzania; Retailleau et al (2017) located the sources of SFMs in both shallow and deep water in the northern Atlantic Ocean by utilizing spurious arrivals based on noise correlation functions (NCFs); derived the sources of SFMs possibly dwell over wide areas of the Atlantic Ocean where the water depth may be up to 2,000 m based on NCFs of data recorded from the east coast of America; and Wang et al (2021) identified a total of five SFMs sources including the deep ocean area in Southern ocean and northern Pacific ocean. In addition, direct observations on ocean bottom seismometers (OBSs) also clearly detected SFMs in deep ocean (e.g., Stephen et al, 2003;Tian & Ritzwoller, 2015;Yang et al, 2012).…”