What is the fine-grained topic of the following text: Heavy rainfall caused a massive landslide along a 70m-long stretch of land along the Tien River in Vinh Lac hamlet of Vinh Hoa commune in Tan Chau town on September 21.The local government moved swiftly and evacuated three households to a safe place. Only return the topic.
Landslide along the Tien River due to heavy rainfall