Guangdong province's emergency management department released an investigation and evaluation report on Wednesday, unveiling the causes of the landslide that occurred on an expressway, causing dozens of deaths and injuries. The report details geographic and weather conditions, as well as public officials who have been disciplined for dereliction of duty.

The landslide occurred at the Chayang section of the Meizhou-Dabu Expressway in the early morning of May 1, causing 23 vehicles to fall and resulting in 52 deaths and 30 injuries, according to the report.

The investigation and evaluation team conducted thorough on-site inspections and various studies to review the disaster and response process. It determined that the combination of prolonged heavy rainfall and various other factors caused this particularly serious landslide.

Guangdong experienced heavy, concentrated rainfall in April last year. Meilin station, approximately 700 meters from the disaster site, recorded a monthly rainfall of 740.5 millimeters, the highest since records began in January 2021, the report said.

As water levels rose, the water pressure, buoyant forces and ability of water to move underground increased. These changes led to a build-up of pressure that softened the ground over time, making it more prone to sliding.

When the lower and middle parts of the embankment and the retaining wall suddenly slid and deformed, it triggered the collapse of the fill soil on the upper part of the embankment, resulting in the landslide on the expressway, according to the report.

Discipline inspection and supervision authorities in Guangdong have taken strict disciplinary actions against 32 public officials from related departments for their dereliction of duty and responsibilities in disaster management.

Among them, Wang Xiaotian, former Party committee member and deputy director of the Guangdong Provincial Highway Administration Center, is currently under disciplinary review and investigation for suspected serious violations of discipline and laws.

Other relevant officials have received disciplinary actions or admonitions according to Party discipline and government regulations. The illegal actions of related enterprises and individuals have been subjected to administrative penalties by the relevant industry regulatory authorities.

The collapse occurred in the early morning, with sporadic light rain, poor visibility for drivers and a sudden increase in traffic flow. After the vehicles fell and caught fire, these adverse factors further exacerbated the impact, the report said.

However, all 30 injured individuals have been successfully treated, and the losses caused by the disaster have been reduced to the greatest extent possible, according to the report.

The eastern extension of the Meizhou-Dabu Expressway resumed traffic in September. Its operation is stable, with a traffic flow comparable to the levels before the incident.