Analysis of acceleration dominant azimuth distribution characteristics of Hualien MS7.3 earthquake

Abstract

On April 3, 2024, an M_S7.3 earthquake occurred in Hualien County, Taiwan. Some strong ground motion acceleration records were captured by the relevant stations of the Central Meteorological Bureau of Taiwan and the Palert earthquake early warning system. Based on these acceleration records, this paper proposes a method for calculating and analyzing the dominant azimuth of strong ground motion. The distribution characteristics of the dominant azimuth of strong ground motion in each region are quantitatively analyzed from the perspective of epicentral distance and geological division and the characteristics of ground motion in sea area are also analyzed. The research results show that the dominant azimuth of strong ground motion is randomly distributed throughout the entire area affected by this earthquake, with no significant dominant azimuth interval. The dominant azimuth of strong ground motion in the near-field region and the eastern coastal area is clearly distributed, with most of the acceleration dominant azimuth distributed in the range 150°-210°. The dominant azimuth of strong ground motion is uniformly distributed in the western impact plain area of Taiwan without significant dominant azimuth interval, while the dominant azimuth of strong ground motion in the eastern mountainous area and the central hilly area is clearly distributed. In addition, the acceleration time history in the sea area shows the characteristic of low frequency and long period.