Active quake zone

Ludian county in Zhaotong, Yunnan province, is located in an active earthquake zone, and it has suffered three earthquakes stronger than magnitude-5 since 2003.

The first of those, on Nov 15, 2003, caused five deaths and injured 29, while the most recent before Sunday's, a magnitude-5.6 quake on Aug 10, 2004, resulted in four deaths and 594 injuries.

Mountainous terrain accounts for 87.9 percent of the county, which is in the northeast part of the province. The county is 447 km from the provincial capital of Kunming, which is in the southwest.

Weather worries

Worsening weather conditions in the quake zone are expected to hamper disaster relief efforts.

The weather forecast predicts heavy rain from Monday night through Tuesday, with light to medium rain on the following days. Because of this, aftershocks could trigger further geological disasters such as landslides.

The minimum temperature in Ludian county at night can be 17 to 18 C and, as a result, tents and quilts are gravely needed for refugees in the quake zone.

Telecommunication repairs

The first few hours of media reports about the quake warned of the poor condition of telecommunications in the affected area.

The county's telecommunications have not been cut completely, and emergency response technicians have been dispatched to make repairs, according to a news release on the website of the Ministry of Industry and Information Technology.

Forty-one base stations - 11.2 percent of all the stations in the county - were out of service, and the number of calls from the region after the earthquake "increased" from the norm, the ministry said.

Shallow quake

Serious damage may be confirmed later because of the shallow nature of the quake, sources from the Seismological Bureau of Yunnan province said.

The focus of the quake was only 12 km below the surface of the Earth, which signifies a very shallow quake that could have a huge impact on the people and buildings above.

The density of the population in Ludian county also might magnify the expected damage. File statistics show the county has 170 people for every square kilometer, and the density of the population in the quake zone is reportedly around 265 people per sq km.