A KARST GEOLOGICAL HAZARD INCIDENT OF NOV.11,1997 IN ZHEMU VILLAGE, GUILIN

A new case of karst collapse ( or called as sinkhole in USA) happened 11:50, Nov.11,1997 in Zhemu village on the west bank of Lijiang River, and 10km southeast of downtown Guilin, the well-known scenic city in South China抯 Guangxi province.

The incident was considered to be related to engineering works carrying out on the Lijiang River, whcih was aimed at improving navigation channel for tourism boats. However, no problem had happened since the engineering work started on Nov.9 until the incident took place. It is said that 15 dynamite explosions had already been made before the collapse, but the amount of dynamite used for each explosion was limited under 2 kg.

On Nov.11,11:30, a stronger explosion was made with more dynamite (Fig.1).

Fig.1, The distribution of collapse pits around Zhemu village ,Guilin

Anyway, it was only 12.8 kg, but disastrous problems followed : on 11:50, namely, 20 minutes after the explosion, a NW oriented collapse 10m long,2-3 m deep took place 25 m away northwest from the explosion point( point 1 in Fig.1, and fig.2). It was dry at first, but inundated on 16:00pm. Soon after the No.1 collapse, a 揼eyser” with a mixture of sand, mud, and water bursted out in the living room of a farmer抯 house(Fig.1,point 2), and then the room was subsided. A new house under construction in the village was destroyed by another collapse(Point 3 in Fig.1, and fig.3). Until Nov.13, the far most collapse took place 500m away to the northwest of the explosion point. A spring with mudy water was found flowing out under Lijiang River near the explosion point(point 4 in Fig.1). No casualty was reported because the incident was taking place in daytime. Investigation and remedation measures are still under way.

Fig.2, A big karst collapse pit on the sand beach, with the engineering explosion point near the boat on the backgroung(No.1 point in Fig.1)

Fig.3, A new house under construction was destroyed (point 3 in Fig.1)

In a Sino-US Workshop on 揘atural Disaster Mitigation and Remedation” (Nov.19-21,1997, Diaoyutai Hotel,Beijing), Yuan Daoxian reported this incident and brought about hot discussions. It was believed that the engineering explosion had activated an underground stream, and a sort of resonance process happened in the underground karst course to make the incident lasting a longer time. According to previous similar experience in other region, the process may last as long as 5 months.

Back to home

Editors: Liu Zaihua / Li Bin / Cao Jianhua. Last revision: Dec.7,1997
Supervisor: YUAN Daoxian.
Any comments and suggestions to Prof. YUAN Daoxian or Dr. LIU Zaihua or webmaster
Copyright to IGCP-379 ,1995-1999.
Copyright to Network Center of Guangxi Normal University, 1995,1996,1997.