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Separation of Intrinsic and Scattering Seismic Wave Attenuation in the Crust of Central and South-Central Alaska

Description: 

Conducting a thorough analysis of seismic hazards is essential for evaluating the potential impact of earthquakes on both structural damage and loss of life in a given area, especially in regions like Alaska, known for frequent seismic activity. The precision of seismic hazard evaluations relies heavily on the dependability of ground motion prediction equations, which forecast the anticipated ground shaking at specific locations. However, in areas with notable disparities in crustal attenuation, such as Alaska, the reliability of these equations may be compromised. The average Lg Q in Alaska significantly surpasses that in the western U.S. and Canada, influencing seismic hazard assessments by affecting the magnitude and duration of ground shaking. Failing to consider these regional variations in crustal attenuation can lead to inaccurate hazard assessments.

To gain a deeper understanding of the underlying factors contributing to this issue, this research proposes the application of Coda Q analysis to investigate the roles of scattering and intrinsic crustal attenuation in central and south-central Alaska. The investigation will specifically target earthquakes with magnitudes ranging from 2 to 6.5, occurring within an epicentral distance of 20km to 200km between December 2014 and December 2020, with focal depths of less than 30km. Utilizing the Multiple Lapse Time Window (MLTW) method with the center frequencies ranging from 0.75 to 12.0 Hz, the study aims to distinguish between intrinsic and scattering crustal attenuation by analyzing seismic energy in three-time windows: 0-15 s, 15-30 s, and 30-45 s, measured from the S arrival. By analyzing the regionalized values of intrinsic and scattering attenuation and their frequency dependencies, the study aims to interpret the causes for regional variations of crustal attenuation of central and south-central Alaska. This understanding can potentially enhance geological and tectonic interpretations, ultimately leading to the refinement of ground-motion prediction equations applicable in seismic hazard assessments.

Session: From Earthquake Recordings to Empirical Ground-Motion Modelling [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Anuradha

Student Presenter: Yes

Invited Presentation: 

Authors