WITHDRAWN Delineating Shallow Sedimentary Structure of Matanuska and Eagle River Areas, Alaska, by Inversion of Horizontal-Vertical Spectral Ratio From Local Earthquakes.
Description:
WITHDRAWN In the aftermath of the 2018 M7.1 earthquake, the Matanuska-Susitna (Mat-Su) Valley and Eagle River areas north of Anchorage suffered extensive damage. There were widespread ground failures, soil liquefaction throughout the region, and damage to schools and residential buildings. However, no strong-motion stations were operational in these areas during this earthquake. As part of a collaboration with the Alaska Earthquake Center, seven strong-motion sensors (Etna2 of Kinemetrics Inc.), including three in the Mat-Su Valley and four in Eagle River, were installed to capture strong-motion data during future earthquakes and examine spatial variations in ground response and its relationship between subsurface geological formations. The network has recorded several local earthquakes of magnitude 4.5 to 6.1 since February 2021. All analyzed recordings were detrended, baseline corrected, and bandpass filtered between 0.1 and 25 Hz to remove dominated noise. The amplitude spectrum of each component was computed using a fast Fourier transform (FFT) and was smoothed by the Konno and Ohmachi window. The Fourier spectra were calculated in a time window of 15 sec starting at the onset of the S waves after tapering with a 5% cosine function. The horizontal-to-vertical spectral ratio (HVSR) for the individual earthquake was calculated by dividing the root-mean-square average spectrum of the north-south and east-west component spectra and that from the vertical. The inversion of computed HVSR was performed using a global optimization technique via simulated annealing (SA) to obtain a 1-D layered earth model with P- and S-wave velocity, density, thickness, and frequency-independent attenuations of P- and S-wave as the model parameters for each layer. The results will show the variation in shallow structures at each station site. A detailed interpretation of ground motion characteristics in terms of layered-earth structure and their relation with the local geology will be presented.
Session: Site-specific Modeling of Seismic Ground Response: Are We Quantitative Enough to Predict? [Poster]
Type: Poster
Date: 4/19/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Utpal Dutta
Student Presenter: No
Invited Presentation:
Authors
Utpal Dutta Presenting Author Corresponding Author udutta2@alaska.edu University of Alaska Anchorage |
Yue Zhao yzhao8@alaska.edu University of Alaska Anchorage |
Zhaohui (Joey) Yang zyang2@alaska.edu University of Alaska Anchorage |
Jillian Holland jgholland@alaska.edu University of Alaska Anchorage |
|
|
|
|
|
WITHDRAWN Delineating Shallow Sedimentary Structure of Matanuska and Eagle River Areas, Alaska, by Inversion of Horizontal-Vertical Spectral Ratio From Local Earthquakes.
Category
Site-specific Modeling of Seismic Ground Response: Are We Quantitative Enough to Predict?