Major earthquakes in mountainous areas usually exert negative impacts on vegetation cover and growth due the numerous coseismic landslides. However, understanding of the duration of these impacts and spatiotemporal dynamics of vegetation recovery dominated by environmental factors remains limited. The present study aimed to investigate the spatiotemporal dynamics of natural vegetation restoration and associated mechanisms in a mountainous basin in southwestern China after the 2008 Wenchuan Ms 8.0 earthquake. The results showed that the normalized difference vegetation index (NDVI) substantially decreased from 0.70 to 0.47 after the earthquake and then gradually increased at an average rate of 0.020 yr(- 1). By 2023, vegetation had been restored to its pre-earthquake levels in 84.9% of the total area. And 15.1% of the land remains unrecovered, with 11.7% covered by landslide slump mass. Approximately 4.16% of the entire basin is projected to recover in the future (theta(slope) > 0, H > 0.5) over a seven-year period. Elevation was the most crucial factor influencing both the damage and recovery of vegetation in the basin, followed by landslide slump mass and soil type. The overall vegetation recovery potential is limited, with an average vegetation restoration potential index (VRPI) of 0.21 in 2023. Notably, 11.2% of the basin exhibited a VRPI > 0.4, mainly situated in the northernmost part, characterized by high altitude (> 3000 m), carbonate-cinnamon soil, and dense distribution of landslide slump mass. The results indicate that natural vegetation has a robust capacity for recovery, albeit hindered by active landslides and fragile high-altitude habitats, where human intervention should be implemented. The results provide valuable information to guide future vegetation restoration planning and layout in Wenchuan earthquake-stricken areas.

The significant duration is a crucial intensity measure for earthquake-resistant design and seismic hazard assessment (SHA). The Sichuan-Yunnan region is characterized by a high level of seismic activity and possesses the most concentrated network of seismic stations in China. The ground motion prediction equation (GMPE) is the predominant approach to estimating significant durations. The existing prediction equations for the significant duration are not well-suited for the Sichuan-Yunnan region. This study used data from the National Strong Motion Observation Network System (NSMONS) of China in this region to develop prediction equations for significant durations of DS5-75 and DS5-95. The equations took into account variables including moment magnitude (M-w), fault distance (R-rup), average shear wave velocity of 30 m on the soil profile (V-S30), and depth to the top of the rupture (Z(tor)). Our database has a singular instance of the Wenchuan earthquake with M-w > 7. The restricted data complicates the calibration of our model for events with M-w > 7. Therefore, we suggest the equations be valid in the Sichuan-Yunnan region for M-w between 4.2 and 7.0, R-rup from 0 to 300 km, and V-S30 values ranging from 139 to 900 m/s.

Post-earthquake scientific investigation is considered as one of the pillars supporting earthquake engineering. On the 6th of February, 2023, two deadly strong earthquakes, which magnitudes were M(w)7.8 and M(w)7.5, respectively, shook Southern-Central Turkiye, caused significantly large casualties and tremendous economy loss. Through on-site field survey, liquefaction phenomena and liquefaction-induced damage to buildings were observed. The observations are: (1) the consequences of soil liquefaction included sandboils, lateral spreading, ground subsidence and ground failure caused by loss of bearing capacity; (2) in two liquefied areas, lateral spreading was investigated and the spreading displacement ranged from several centimeters to meters, resulting in damage or demolishing of buildings; (3) in Golbasi town, many 6 to 10-story buildings significantly subsided and tilted due to liquefaction-induced loss of ground bearing capacity. Buildings subsided by tens of centimeters to 2 similar to 3 m, and tilted by several degrees to tens of degrees; (4) ground subsidence of tens of centimeters with respect to adjacent buildings was detected. The liquefaction phenomena were compared with those triggered by the 2008 Wenchuan, China, earthquake which maintained similar in magnitude and focal depth. The findings and lessons learnt will enhance the understanding of liquefaction hazard, challenge the current liquefaction countermeasures, and eventually facilitate to improve liquefaction mitigation techniques.