I think one of the main causes of landslides is removing part of a mountain to build houses.
ーI think one of the main causes of landslides is removing part of a mountain to build houses.
「地滑りの要因の一つは、山の一部を取り除いて住宅地を建てたことです」
main causes で「要因・主な原因」
landslide で「地滑り」
to remove で「取り除く」
to build houses で「家々を建てる」
ご参考まで!