Where does the extremely destructive sand surge come from?

recently

Affected by the 6.2-magnitude earthquake in Jishishan County, Gansu

Bordering Jishishan County

Jintian Village and Caotan Village in Minhe County, Haidong City, Qinghai Province

A secondary disaster occurred: sand surge

A large amount of silt poured into two villages

Some houses were destroyed

Where on earth does this mud come from?

Why does it keep gushing out from the ground?

Sand surge diagram picture from the Internet

After the earthquake

Due to the vibration of the earth's crust

Water-bearing sand deep underground

A strong liquefaction phenomenon will be formed

The soil, which was originally solid, becomes liquid.

or thick liquid

Under repeated shocks from external forces

Liquefied sand is compressed

Causes water pressure in the gap to increase

Follow a certain passage directly to the surface

Soil liquefaction pictures from the Internet

generally

Ground near water

Water will seep out if you step on it

And the more you step on it, the softer it gets.

Even finally become like mortar or mud

When this liquefaction occurs deep in the earth

The liquefied soil will burst out from the cracks.

The pictures of the sand surge scene come from The Paper

The river ditch sediment picture comes from the Internet

It is reported that

At the fork in the road not far from Jintian Village

There is a river

The river doesn't have much water on weekdays.

Except for the rainy season, the ditch is basically dry.

After the earthquake

Due to the high groundwater level

The mud from the bottom was stirred up

This ditch is wide upstream and narrow downstream.

The width has been reduced from more than 20 meters to 3~4 meters

As the river narrows

The mud is impassable.

Then overflowed into the river

Jintian Village pictures are from the Internet

According to experts

Sand surge and water content of underground aquifer

Related to the degree of extrusion deformation

Not related to aftershocks

The China Water Science Popularization China, CCTV News, Digital Beijing Science Center, etc. Some pictures are from the Internet. If there is any infringement, please contact us to delete them.

Copywriter | Deng Wanying

Review | Chen Rui

Producer | Fan Yizi

Editor | Wang Ziyue

Proofreading | Meng Jing