Nature of the Ambient Noise, Site Response, and Orientation of Ocean‐Bottom Seismometers (OBSs): Scientific Results of a Passive Seismic Experiment in the Andaman Sea

Abstract

Research Article| November 28, 2017 Nature of the Ambient Noise, Site Response, and Orientation of Ocean‐Bottom Seismometers (OBSs): Scientific Results of a Passive Seismic Experiment in the Andaman Sea Pawan Dewangan; Pawan Dewangan aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Search for other works by this author on: GSW Google Scholar Ramakrushana Reddy; Ramakrushana Reddy aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Search for other works by this author on: GSW Google Scholar K. A. Kamesh Raju; K. A. Kamesh Raju aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Search for other works by this author on: GSW Google Scholar Pabitra Singha; Pabitra Singha aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Search for other works by this author on: GSW Google Scholar K. K. Aswini; K. K. Aswini aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Search for other works by this author on: GSW Google Scholar V. Yatheesh; V. Yatheesh aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Search for other works by this author on: GSW Google Scholar K. Samudrala; K. Samudrala aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Search for other works by this author on: GSW Google Scholar M. Shuhail M. Shuhail aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Search for other works by this author on: GSW Google Scholar Author and Article Information Pawan Dewangan aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Ramakrushana Reddy aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org K. A. Kamesh Raju aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Pabitra Singha aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org K. K. Aswini aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org V. Yatheesh aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org K. Samudrala aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org M. Shuhail aCSIR‐National Institute of Oceanography, Dona Paula, Goa 403004, India, pdewangan@nio.org, ramareddy@nio.org, kamesh@nio.org, psingha@nio.org, aswinik@nio.org, yatheesh@nio.org, samudrala@nio.org, mshuhail@nio.org Publisher: Seismological Society of America First Online: 28 Nov 2017 Online Issn: 1943-3573 Print Issn: 0037-1106 © Seismological Society of America Bulletin of the Seismological Society of America (2018) 108 (1): 248–259. https://doi.org/10.1785/0120170163 Article history First Online: 28 Nov 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Pawan Dewangan, Ramakrushana Reddy, K. A. Kamesh Raju, Pabitra Singha, K. K. Aswini, V. Yatheesh, K. Samudrala, M. Shuhail; Nature of the Ambient Noise, Site Response, and Orientation of Ocean‐Bottom Seismometers (OBSs): Scientific Results of a Passive Seismic Experiment in the Andaman Sea. Bulletin of the Seismological Society of America 2017;; 108 (1): 248–259. doi: https://doi.org/10.1785/0120170163 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract We analyze the nature of the ambient noise and site response for ocean‐bottom seismometers (OBSs) deployed in the Andaman region. The probabilistic power spectral densities of the OBSs show that the noise level in the Andaman region is within the range of Peterson's new low‐noise model and new high‐noise model (NHNM) when considering short periods (⁠<20 s⁠). When examining long periods (⁠>20 s⁠), the noise level is higher than what would be given by NHNM. The peak associated with secondary microseisms occurs between 3 and 6 s. The stations that are close to the Andaman and Nicobar Islands show a prominent secondary microseismic peak at 4 s, whereas the stations farther away show a small hump at 1 s. The noise level varies seasonally and shows a strong correlation with the significant wave height computed from WAVEWATCH III. The ambient noise is down to −140 dB for the band from 0.1 to 1 s, which provides the best signal‐to‐noise ratio level for local earthquakes. For very short periods (⁠<0.1 s⁠), the ambient noise level increases to −120 dB⁠; this is likely due to the efficient propagation of seismic energy through the low attenuation oceanic crust. The horizontal‐to‐vertical spectral ratio (HVSR) of the ambient noise curves shows an amplification factor greater than four. Furthermore, the HVSR curves show a broad or flat peak beneath the seamounts and the accretionary prism and a sharp or clear peak in the basinal area. We also estimate the orientation of the OBSs using Rayleigh‐wave polarization analysis. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

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