July 9, 2009, M6.0 Earthquake

Available Information



Junwu Dai of the Institute of Engineering Mechanics in the China Earthquake Administration provided the following information:

An Ms6.0 earthquake struck Guantun of Yaoan County in the Yunnan Province of China at 19:19 p.m. July 9, 2009.The epicenter was located at latitude N25°36’, longitude E101°06’, with maximum damage intensity VIII. One person was killed and 31 severely wounded. The earthquake caused about 2.15 billion Chinese yuan in direct economic losses, including damage to local buildings and lifeline systems as well as other structures in seven counties (Yaoan, Dayao, Nanhua, Mouding, Yongren, Xiangyun and Binchuan). The total damaged area is about 6,958 square km, with 230 square km of inten- sity VIII, 883 square km of intensity VII, and 5,845 square km of intensity VI.


The details of the strongest ground motion recorded by The Yunnan Digital Strong Motion Net in the earthquake are listed below.

Event Station Distance


Ms 6.0 Hedian,Xiangyun 31.3
28.5 80.8 70.8


 Details of the strongest ground motion recorded in Yaoan EQ


Based on the field investigation to 150 residential communities, the intensity contour is determined in fig.1.  The total damaged area is about 6958 square Km with 230 square Km of intensity Ⅷ area, 883 square Km of intensity VII area and 5845 square Km of intensity VI area

Damage Characteristics

    1. Damage to buildings:


    1. In the damage intensity VIII area, adobe/wood structures are the principal building type. Severe damage or collapse occurred to 42% of them, 48% were lightly damaged, and 10% undamaged. A small quantity of brick buildings collapsed; most were lightly damaged or undamaged. In the intensity VII area, few adobe/wood and brick/wood buildings collapsed or were seriously damaged. In the intensity VI area, most buildings remained intact except for a few seriously damaged very old adobe or brick houses.


    1. Damage to infrastructure:


  1. Impacts to transportation systems included roadbed collapse, road subsidence, road surface cracks, slope collapse, culvert cracks, and bridge damage. Impacts to the power supply system included transmission pole collapse, lines broken, and damage to transformers and meters. Damage occurred to network and telecommunication facilities and broadcasting facilities. The water supply and wastewater systems sustained cracked pipelines, and reaction tank walls and joint leakage. Impacts to the hydraulic system included individual dam deformation, dam shoulder and foot leakage, anchor gate deformation, culvert leakage, irrigation canal cracks, and operation panel damage.