Analysis and Modeling of High-Frequency Emission and Deep Seismic Sources of Sunquakes

TL;DR

This study investigates the high-frequency and deep seismic sources of sunquakes, analyzing observational data and performing numerical simulations to understand their spectral characteristics and source amplitudes.

Contribution

It provides new insights into the spectral properties and depth dependence of sunquake sources through independent analysis and modeling.

Findings

A wavefront is detected at 8 mHz but not at 10 mHz.

Simulations show peak frequency decreases with increasing source depth.

The estimated source amplitude is too low to explain observed wavefronts.

Abstract

Recent work published by Lindsey et al find evidence for a deep and compact seismic source for the sunquake associated with the 2011 July 30 M9.3 flare, as well as seismic emission extending up to 10 mHz. We examine the sunquake independently, and a possible wavefront is found in the 8 mHz band, though no wavefront is easily discernible in the 10 mHz band. Additionally, we perform numerical simulations of seismic excitation modeled with the reported parameters and changes in the power spectra with increasing depth of the excitation source are examined. It is found that the peak frequency decreases for increasing depths, but a shallow minimum is indicated between z=0 and z=-840 km. Analysis of the suspected wavefront of the M9.3 sunquake finds that the power spectrum of the reported seismic emission is close to that of background oscillations, though with a peak frequency noticeably lower than the background peak. Additionally, it is found that the amplitude of the source estimated by Lindsey et al is too low to produce the observed wavefront.