Site Response Characteristics from Ambient Noise Data Recorded on Degrading Warm Permafrost in Bethel, Alaska.
Description:
Permafrost is experiencing accelerated warming due to anthropogenic activities and climate change. The intricate relationship between permafrost degradation and seismic attributes is significant to regions where both phenomena are prevalent, as it can exacerbate seismic hazards. There is a notable knowledge gap about this relationship. The current study aims to address the gap by analyzing twelve months of recorded ambient noise time series data from two accelerometers located on warm permafrost in Southwest Alaska. Both accelerometers were three-component EpiSensors connected with a 24-bit Delta-Sigma converter with a dynamic range of approximately 136 dB per channel (Etna-2 of Kinemetrics). Data from each sensor was sampled at 250 samples per second. An open-source, web-based application called HVSRweb was employed for horizontal-to-vertical spectral ratio (HVSR) processing; a processing window length of 60 seconds was used to create 60-time window lengths of 60 seconds each. The microtremor HVSR method provided insights into how the site response differs between winter and summer seasons. Comprehensive analysis of the time series data collected from the two seismic sensors during winter and summer revealed an obvious correlation between the frozen or unfrozen active layer conditions and ground motion amplification. Ground motion amplification was notably higher during summer with an unfrozen active layer. The peak fundamental frequency (f0) of the HVSR has also been shifted towards the higher frequency side during the winter months due to frozen ground. These findings demonstrate the relationship between permafrost degradation and ground motion amplification, emphasizing the importance of permafrost degradation on seismic attributes. These observations are crucial for understanding and predicting the potential impact of permafrost degradation on the built infrastructure in future seismic events.
Session: How Well Can We Predict Broadband Site-Specific Ground Motion and Its Spatial Variability So Far? - I
Type: Oral
Date: 5/1/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Annika
Student Presenter: Yes
Invited Presentation:
Authors
Annika Goozen Presenting Author Corresponding Author annikagoozen@yahoo.com University of Alaska Anchorage |
Yue Zhao yzhao8@alaska.edu University of Alaska Fairbanks |
Utpal Dutta udutta2@alaska.edu University of Alaska Anchorage |
Zhaohui (Joey) Yang zyang2@alaska.edu University of Alaska Anchorage |
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Site Response Characteristics from Ambient Noise Data Recorded on Degrading Warm Permafrost in Bethel, Alaska.
Category
How Well Can We Predict Broadband Site-Specific Ground Motion and Its Spatial Variability So Far?