Seasonal changes in shallow earth structure in the permafrost region of Alaska
We analyzed data from the EarthScope Transportable Array in Alaska in order to understand the nature of near-surface melting in the permafrost region. Data consisted of (1) temperature, (2) vertical seismic data, (3) horizontal seismic data, and (4) wind data. Observations at some stations indicate...
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ftgfzpotsdam:oai:gfzpublic.gfz-potsdam.de:item_5016121 2023-06-11T04:12:33+02:00 Seasonal changes in shallow earth structure in the permafrost region of Alaska Tanimoto, T. Anderson, A. 2023 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016121 eng eng info:eu-repo/semantics/altIdentifier/doi/10.57757/IUGG23-0351 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016121 XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG) info:eu-repo/semantics/conferenceObject 2023 ftgfzpotsdam https://doi.org/10.57757/IUGG23-0351 2023-04-23T23:38:34Z We analyzed data from the EarthScope Transportable Array in Alaska in order to understand the nature of near-surface melting in the permafrost region. Data consisted of (1) temperature, (2) vertical seismic data, (3) horizontal seismic data, and (4) wind data. Observations at some stations indicate a rapid melting phenomena in the summer that causes a thousandfold increase in horizontal power spectral density. This rapid rise in horizontal seismic noise typically occurs in July, lasting about 30 days. The initiation of this major melting period does not happen immediately after the surface temperature exceeds 0 o C; instead, there is a delay of about a month. After the peak horizontal amplitude is reached, it gradually returns to the pre-melting level. Many stations show that this return occurs by December. However, some stations require until March or April in the following year to arrive back to their pre-melting level. For all stations, this return occurs well after the surface temperature becomes negative in September or October. This suggests that the melt layer remains at depth as surface temperatures drop below freezing, perhaps sandwiched between the developing ice from the surface and the underlying permafrost ice. However, we noted some caution is required at a few stations because a transient surge in horizontal amplitudes occurs in February and November that appears to be correlated with winds. We summarize the temporal characteristics of individual stations, their seasonal geographic patterns throughout Alaska and a potential mechanism to explain a sudden increase of horizontal noise. Conference Object Ice permafrost Alaska GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) |
institution |
Open Polar |
collection |
GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) |
op_collection_id |
ftgfzpotsdam |
language |
English |
description |
We analyzed data from the EarthScope Transportable Array in Alaska in order to understand the nature of near-surface melting in the permafrost region. Data consisted of (1) temperature, (2) vertical seismic data, (3) horizontal seismic data, and (4) wind data. Observations at some stations indicate a rapid melting phenomena in the summer that causes a thousandfold increase in horizontal power spectral density. This rapid rise in horizontal seismic noise typically occurs in July, lasting about 30 days. The initiation of this major melting period does not happen immediately after the surface temperature exceeds 0 o C; instead, there is a delay of about a month. After the peak horizontal amplitude is reached, it gradually returns to the pre-melting level. Many stations show that this return occurs by December. However, some stations require until March or April in the following year to arrive back to their pre-melting level. For all stations, this return occurs well after the surface temperature becomes negative in September or October. This suggests that the melt layer remains at depth as surface temperatures drop below freezing, perhaps sandwiched between the developing ice from the surface and the underlying permafrost ice. However, we noted some caution is required at a few stations because a transient surge in horizontal amplitudes occurs in February and November that appears to be correlated with winds. We summarize the temporal characteristics of individual stations, their seasonal geographic patterns throughout Alaska and a potential mechanism to explain a sudden increase of horizontal noise. |
format |
Conference Object |
author |
Tanimoto, T. Anderson, A. |
spellingShingle |
Tanimoto, T. Anderson, A. Seasonal changes in shallow earth structure in the permafrost region of Alaska |
author_facet |
Tanimoto, T. Anderson, A. |
author_sort |
Tanimoto, T. |
title |
Seasonal changes in shallow earth structure in the permafrost region of Alaska |
title_short |
Seasonal changes in shallow earth structure in the permafrost region of Alaska |
title_full |
Seasonal changes in shallow earth structure in the permafrost region of Alaska |
title_fullStr |
Seasonal changes in shallow earth structure in the permafrost region of Alaska |
title_full_unstemmed |
Seasonal changes in shallow earth structure in the permafrost region of Alaska |
title_sort |
seasonal changes in shallow earth structure in the permafrost region of alaska |
publishDate |
2023 |
url |
https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016121 |
genre |
Ice permafrost Alaska |
genre_facet |
Ice permafrost Alaska |
op_source |
XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.57757/IUGG23-0351 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016121 |
op_doi |
https://doi.org/10.57757/IUGG23-0351 |
_version_ |
1768388501641887744 |