Home > Reconnaissance Activities > China > M 6.0 Yunnan, China 09.07.2009
July 9, 2009 USGS EARTHQUAKE LIST
RECONNAISSANCE ACTIVITIES Overview of Yaoan (Yunnan Province, China) Ms6.0 Earthquake Junwu Dai of the Institute of Engineering Mechanics in the China Earthquake Administration provided the following information: Download Report 1.3MB 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
(km) | | Ms 6.0
| Hedian,Xiangyun | 31.3 | | 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 - Damage to buildings:
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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. - Damage to infrastructure:
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.
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Last Updated on Tuesday, 05 January 2010 10:33 |
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Images courtesy of the EERI Reconnaissance Team
 Typical damage pattern of better quality URM buildings in downtown L’Aquila consisted of generalized cracking of the masonry walls, especially between openings and in corners, leading to loss of the superficial plaster.  Better construction quality and recently retrofitted buildings downtown L’Aquila suffered minor or no damage.  Several displayed cross-ties (catene in Italian).  The concrete shows an anomalous distribution of fine aggregates and cement, yielding a mix of larger aggregates without a dense cohesive matrix. [Photo: Guillermo Franco]  Pancake collapse of third story over the second story in a four story building downtown L’Aquila. [Photo: Guillermo Franco]  Classical example of pounding between two adjacent buildings downtown L’Aquila. [Photo: Guillermo Franco]  Via degli Angeli in Paganica, typical of many towns built with level streets parallel to the hillside and short steep streets connecting them.  Destroyed church and neighboring homes in San Gregorio, with earthquake victim searching for possessions.  In the San Salvatore Hospital, the main hospital in the L’Aquila province, damage occurred to a few concrete columns in three of its many buildings.  San Salvatore Hospital: Occasional interior damage & falling hazards at stairway due to poor seismic joint detailing. Thick heavy plaster over joint. Similar poor joint detailing widespread at exterior veneer.  San Salvatore Hospital: Occasional instances of fallen unsecured medical equipment, yet damage to this nonstructural content was limited and not likely a significant operational factor  Newly built one-story RC schoolbuilding in Onna with no evident damage; structures on the opposite side of the street suffered partial or complete collapse.  The damage observed to industrial facilities in the area around l’Aquila was mainly to non-structural elements (e.g., partitions and ceiling tiles) and to contents.  Failure of roof interior panels and insulation in an industrial facility.  At a manufacturing plant, three tall steel silos, storing polypropylene beads, that were full during the earthquake either collapsed or suffered extensive damage.  The silos also crumpled at their bases.  Collapsed bridge, over the river Aterno near Fossa, of reinforced concrete construction, with three continuous spans. The collapse was likely induced by failure of the columns.  Damaged bridge close to Onna, of same design as collapsed bridge near Fossa, showed evidence of damage in the column hinge.  Closed exit of Provincial Route 38, from L'Aquila to Avezzano.  Along the road to Fossa, minor slide at road embankment, though still retained by the wire protection.
Photos from EERI's Reconnaissance Team  Hotel Montana  Ministry of Agriculture  St. Francois de Sale Hospital, interior scene  Port  U.N. Annex building, interior  U.N. Annex building, exterior  St. Francois de Sale Hospital, exterior  Delmas Boys' School, exterior  Hillside Construction  Institut St. Paul Primary School  Delmas Boys' School, interior
Photos courtesy of Steve Baldridge  Within the inundation zone most all of the wood framed residences were leveled down to the foundation.  Many of the low lying villages have churches near and facing the ocean. The typical construction is a combination of concrete frames and CMU (concrete masonry unit) infill. There were several examples of the tsunami waters entering the churches through the front door and flowing out the windows along the sides of the church. While doors, windows and interior furniture were damaged the structures did not appear to have any distress from the hydrostatic loading. This picture shows the pews having been ripped from the slab as the tsunami waters rushed through the church.  In addition to the damage from the tsunami waters there were examples of large localized damage to buildings from floating debris, typically vehicles and empty shipping containers.  While most CMU (concrete masonry unit) buildings withstood the tsunami waters there were poorly constructed CMU buildings that did not fare well. The house in this picture was leveled to its foundation while other nearby masonry buildings survived. Many of the block cells in the walls of this CMU building were not grouted, including many of the cells that had reinforcing steel in them.  There did not appear to be much, if any, damage from the seismic event. This school, located out of the inundation zone, however exhibited some odd horizontal cracking along the top reinforcing steel in concrete frame members. This may be due to some pre-existing corrosion or construction issue that had been aggravated by the ground motion of the earthquake.  This CMU (concrete masonry unit) building withstood most of the force of the tsunami waters except for an area at the back of the residence. It appears that there was some scouring of the foundation that may have weakened the connection of the CMU walls at their base. The force of the water passing through the house and trying to exit through small window openings would have created large forces on this wall.
Photos courtesy of Junwu Dai  Collapsed adobe-wood building in epicenter area  Collapse of exterior adobe wall  Collapse of exterior adobe wall  Damage of adobe buildings  Damage of brick school building  Damage of brick school building
 Damaged building, Bailu, Wenchuan 2008 [photo: V. Cedillos, Project Manager, GeoHazards Intl]  Ground settlement in Bailu, Wenchuan 2008 [photo: V Cedillos, GeoHazards Intl]  Fault rupture at Bailu Middle School did little damage to new building (left), Wenchuan 2008 [photo: M Lew]  Temporary housing in Bailu, Wenchuan 2008 [photo: V Cedillos, GeoHazards Intl]  Timber lace construction, Bailu, Wenchuan 2008 [photo: V Cedillos, GeoHazards Intl]  Bridge, Wenchuan 2008 [photo: M Lew]  Collapsed spans of reinforced concrete arch bridge, Xiao Yu Dong [photo: Build Change]  GaoYuan Bridge [photo: Build Change]  Han Wang High School shear wall, external view [photo: Build Change]  Adjacent bldgs may have averted collapse of 5-story masonry bldg in Dujiangyan [photo: Build Change]  Ground floor column failure (see previous image) [photo: Build Change]  6-story unreinforced masonry bldg with precast concrete plank floors, Dujiangyan [photo: Build Change]  Precast concrete plank rubble, collapsed unreinforced masonry bldg, Dujiangyan [photo: Build Change]  Damaged multistory building, Dujiangyan, Wenchuan [photo: V Cedillos, GeoHazards Intl]  Damaged 6-story residential bldg, Dujiangyan, Wenchuan 2008 [photo: M Lew]  Temporary housing, Dujiangyan, Wenchuan 2008 [photo: V Cedillos, GeoHazards Intl]  Dujiangyan Shelter, Wenchuan 2008 [photo: M Lew]  Shelter in Dujiangyan, Wenchuan 2008 [photo: M Lew]  Reconnaissance team near Gaoyuan Village, Wenchuan 2008 [photo: M Lew]  Damaged buildings at Lidui Park, Wenchuan 2008 [photo: M Lew]  Residential building, Phoenix Lane, Wenchuan 2008 [photo: M Lew]  Shenxigou, Wenchuan 2008 [photo: M Lew]  Tonji Middle School, Wenchuan 2008 [photo: M Lew]  Xiaoyudong Bridge damaged by fault rupture thrusting abutment, Wenchuan 2008 [photo: M Lew]  Collapse of bldgs straddling fault running through town of Xiaoyudong, Wenchuan 2008 [photo: M Lew]  Damaged aluminum plant at Xuankou, Wenchuan 2008 [photo: M Lew]  Landslide in Yinchanggou, Wenchuan 2008 [photo: M Lew]  Damaged building in Yingxiu, Wenchuan 2008 [photo: M Lew]  Interview with local colleague in Yingxiu, Wenchuan 2008 [photo: M Lew]  Extensive damage in Yingxiu, Wenchuan 2008 [photo: M Lew]
Additional images avalable on CD-ROM  Church in town of Santa Cruz Analquito not damaged at all in January and seriously damaged in February  Seriously damaged church in Sonsonate  View of a destroyed adobe house in Candelaria  Damage to house in Cojutepeque  Significant lateral spreading on banks of Rio Lempa  Corroded pilings at the Port of Triunfo fell during the earthquake
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