Why have new lakes formed in china due to the earthquake?

Question

i just read it on the news..and i am wondering how the lakes formed?

Answer 1

Massive landslides resulting from the strong earthquake of 7.8 magnitude on May 12, 2008 in southwest China, have led to the formation of at least 21 lakes in various cities after land blocked the rivers flow. Water has been flowing over some of these blockages in Qingchuan county, but posed no danger.

Expert teams, comprising at least two water conservancy specialists and 10 People's Liberation Army personnel, have been deployed at each of these newly formed lakes to monitor the situation and evacuate the residents in case of any danger.

The landslide blockages have been reported in Beichuan and Anxian counties in the city of Mianyang, Qingchuan county of Guangyuan, Mianzhu and Shifang cities of Deyang, and Pengzhou city near the provincial capital Chengdu.

The three lakes had more than 10 million cu m of water, and more than 20 million cu m of rocks slid into rivers after the quake and formed the lakes said an official with the headquarters for quake relief in Qingchuan.

Seven more landslide blockages were found in Beichuan county, about 160 km from the epicenter, Wenchuan.

Answer 2

The earthquake happened in a mountainous region, and it caused massive landslides which blocked several river valleys like a dam wall, so that lakes (or dams) formed behind the slides.  Once the level of the water rises to the top of the slipped material, it will quickly erode through it possibly causing severe flooding.