Analysis on the Characteristics and Spatial Distribution Patterns of Highway Damage caused by the M_S6.8 Luding Earthquake

On September 5, 2022, an M_S6.8 earthquake struck Luding County, Kardze Prefecture, Sichuan Province—an area that is particularly vulnerable to geological changes. The earthquake caused considerable damage along the highway, leading to road disruptions and blockages, further isolating earthquake-stricken areas. Accordingly, a rapid survey of the main highways in this area was conducted, and 507 damage points were identified. Roadbed damage accounted for more than 70% of the total damages. Co-seismic disasters were primarily distributed along the highways on both sides of the Dadu River in the reservoir area of the Dagangshan Hydropower Station, Caoke Township, and Detuo Township. Further, six factors under three categories of the spatial distribution of highway damage in the earthquake-stricken areas were analyzed. The rate of highway damage was positively correlated with the seismic intensity but negatively correlated with the fault and river distances. The earthquake intensity had the most significant impact: 37.5% of road disruptions were found in areas with an intensity of IX; this percentage was 1.6 and 5.8 times greater than those found in areas with intensities of VIII and VII, respectively. The roads with the most significant damage were in regions with intensities above VIII, faults within 5 km, slopes within 30°–70°, rivers within 100 m, and the presence of granite. This indicated that these factors aggravated highway disruption, resulting in more than 90% of damaged highways in strongly shaken regions. Our findings may provide guidance for efficient highway recovery following earthquakes.