Passive seismic investigations of subaquatic permafrost
Large quantities of organic carbon are known to be sequestered within subaquatic permafrost as gas hydrates. Therefore, knowledge of the extent and thaw rate is of critical importance to our understanding of global climate change. Investigations of sub-aquatic permafrost have focussed on its physica...
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ftawi:oai:epic.awi.de:54997 2024-09-15T18:17:35+00:00 Passive seismic investigations of subaquatic permafrost Rasmussen, Christian Overduin, Paul Boike, Julia Ryberg, Trond Haberland, Christian 2021-04-29 https://epic.awi.de/id/eprint/54997/ https://doi.org/10.5194/egusphere-egu21-12118 https://hdl.handle.net/10013/epic.faa581b1-adb1-4b6d-ab6d-6bf986d6d829 unknown Rasmussen, C. , Overduin, P. orcid:0000-0001-9849-4712 , Boike, J. orcid:0000-0002-5875-2112 , Ryberg, T. and Haberland, C. (2021) Passive seismic investigations of subaquatic permafrost , EGU General Assembly 2021, online, 19 April 2021 - 30 April 2021 . doi:10.5194/egusphere-egu21-12118 <https://doi.org/10.5194/egusphere-egu21-12118> , hdl:10013/epic.faa581b1-adb1-4b6d-ab6d-6bf986d6d829 EPIC3EGU General Assembly 2021, online, 2021-04-19-2021-04-30Passive seismic investigations of subaquatic permafrost Conference notRev 2021 ftawi https://doi.org/10.5194/egusphere-egu21-12118 2024-06-24T04:27:29Z Large quantities of organic carbon are known to be sequestered within subaquatic permafrost as gas hydrates. Therefore, knowledge of the extent and thaw rate is of critical importance to our understanding of global climate change. Investigations of sub-aquatic permafrost have focussed on its physical characteristics via drilling or probing, and through the limited application of geophysical methods. Active seismic methods have been most widely employed, especially for petroleum exploration, but recently passive methods have been used to investigate the seabed using ambient noise. The Horizontal-to-Vertical Spectral Ratio (HVSR) method has previously been shown to accurately determine permafrost thaw depth below the sea floor in marine and lacustrine environments, based on the collection of seismic data over a period of weeks. In this study, we test the use of short-term seabed HVSR seismic surveys and explore possibilities for optimizing the method in a wide variety of subaquatic environments. The method was successfully used in a thermokarst lake, a lagoon and river channels of the Lena Delta (Russia), as well as in marine shelf environments in the Laptev Sea (Russia) and Tuktoyaktuk Island (NW Canada). Study areas where validation data was available were preferred and selected when possible. A passive seismic measuring device, consisting of a watertight metal cannister containing three-component broad-band seismometers, was lowered down to the sea floor from a small boat and left to collect data for 3-4 minutes. The data was recorded at a sample rate of 100Hz. Post-processing and analysis were done with MATLAB. The three seismic signals were individually detrended, the offset was removed and the power spectral density was calculated. The smoothing function proposed by Konno and Ohmachi (1998) was applied to each signal with a smoothing coefficient of 40. Lastly the H/V (Horizontal / Vertical) amplitude was calculated. The H/V amplitude was plotted against signal frequencies from 0 to 50 Hz. The peak resonance ... Conference Object laptev Laptev Sea lena delta permafrost Thermokarst Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
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ftawi |
language |
unknown |
description |
Large quantities of organic carbon are known to be sequestered within subaquatic permafrost as gas hydrates. Therefore, knowledge of the extent and thaw rate is of critical importance to our understanding of global climate change. Investigations of sub-aquatic permafrost have focussed on its physical characteristics via drilling or probing, and through the limited application of geophysical methods. Active seismic methods have been most widely employed, especially for petroleum exploration, but recently passive methods have been used to investigate the seabed using ambient noise. The Horizontal-to-Vertical Spectral Ratio (HVSR) method has previously been shown to accurately determine permafrost thaw depth below the sea floor in marine and lacustrine environments, based on the collection of seismic data over a period of weeks. In this study, we test the use of short-term seabed HVSR seismic surveys and explore possibilities for optimizing the method in a wide variety of subaquatic environments. The method was successfully used in a thermokarst lake, a lagoon and river channels of the Lena Delta (Russia), as well as in marine shelf environments in the Laptev Sea (Russia) and Tuktoyaktuk Island (NW Canada). Study areas where validation data was available were preferred and selected when possible. A passive seismic measuring device, consisting of a watertight metal cannister containing three-component broad-band seismometers, was lowered down to the sea floor from a small boat and left to collect data for 3-4 minutes. The data was recorded at a sample rate of 100Hz. Post-processing and analysis were done with MATLAB. The three seismic signals were individually detrended, the offset was removed and the power spectral density was calculated. The smoothing function proposed by Konno and Ohmachi (1998) was applied to each signal with a smoothing coefficient of 40. Lastly the H/V (Horizontal / Vertical) amplitude was calculated. The H/V amplitude was plotted against signal frequencies from 0 to 50 Hz. The peak resonance ... |
format |
Conference Object |
author |
Rasmussen, Christian Overduin, Paul Boike, Julia Ryberg, Trond Haberland, Christian |
spellingShingle |
Rasmussen, Christian Overduin, Paul Boike, Julia Ryberg, Trond Haberland, Christian Passive seismic investigations of subaquatic permafrost |
author_facet |
Rasmussen, Christian Overduin, Paul Boike, Julia Ryberg, Trond Haberland, Christian |
author_sort |
Rasmussen, Christian |
title |
Passive seismic investigations of subaquatic permafrost |
title_short |
Passive seismic investigations of subaquatic permafrost |
title_full |
Passive seismic investigations of subaquatic permafrost |
title_fullStr |
Passive seismic investigations of subaquatic permafrost |
title_full_unstemmed |
Passive seismic investigations of subaquatic permafrost |
title_sort |
passive seismic investigations of subaquatic permafrost |
publishDate |
2021 |
url |
https://epic.awi.de/id/eprint/54997/ https://doi.org/10.5194/egusphere-egu21-12118 https://hdl.handle.net/10013/epic.faa581b1-adb1-4b6d-ab6d-6bf986d6d829 |
genre |
laptev Laptev Sea lena delta permafrost Thermokarst |
genre_facet |
laptev Laptev Sea lena delta permafrost Thermokarst |
op_source |
EPIC3EGU General Assembly 2021, online, 2021-04-19-2021-04-30Passive seismic investigations of subaquatic permafrost |
op_relation |
Rasmussen, C. , Overduin, P. orcid:0000-0001-9849-4712 , Boike, J. orcid:0000-0002-5875-2112 , Ryberg, T. and Haberland, C. (2021) Passive seismic investigations of subaquatic permafrost , EGU General Assembly 2021, online, 19 April 2021 - 30 April 2021 . doi:10.5194/egusphere-egu21-12118 <https://doi.org/10.5194/egusphere-egu21-12118> , hdl:10013/epic.faa581b1-adb1-4b6d-ab6d-6bf986d6d829 |
op_doi |
https://doi.org/10.5194/egusphere-egu21-12118 |
_version_ |
1810455645982294016 |