The Ms 8.0 Wenchuan earthquake of 12 May 2008 reconnaissance report

Abstract

On 12 May 2008 at 2.28 pm Beijing Time, an Ms 8.0 earthquake occurred in the Wenchuan County of Sichuan province, China. The associated fault ruptured over 240 km on the ground surface. The resulting damage was very severe and widespread, with casualties of almost 70,000, another 18,000 missing and 370,000 injured. The New Zealand Society for Earthquake Engineering reconnaissance team observed the effects and the recovery from this massive earthquake. The team studied the damages caused to the natural and the built environment due to fault rupture, seismic shaking, huge landslides and rockfalls. Maximum shaking intensity of MM XI significantly exceeded design intensity of MM VII for the area. Earthquake induced landslides had a major and catastrophic impact on development and infrastructure in this earthquake. Site selection was demonstrated to be critical. Brittle or non-ductile and irregular buildings performed very poorly especially in a seismic overload situation. Well engineered structures and dams performed well. Lifeline facilities were severely damaged, which resulted in interruptions to key transportation routes, inhibited rescue and recovery operations.

Integrated Wellington region land transport resilience study

“…A key observation from the 2010-2011 Canterbury earthquake sequence which reinforced overseas observations during reconnaissance after the Wenchuan earthquake in China in 2008 [20], was that access along inner-city transport routes were closed due to damage or collapse of buildings and safety hazards posed by buildings damaged by the earthquakes and aftershocks, even where the roads themselves were not damaged.…”

“…The areas of influence of buildings was assessed based on their heights using GIS. The likely closure of routes was based on these parameters and observations during the 2010-2011 Canterbury Earthquake Sequence and overseas observations [20].…”

“…Study considered multi-modal transport, and this was explicit in the way the importance was derived considering public transport routes. Since the same level of resilience assessment had not been carried out for the railway system, the resilience of railway system was considered more subjectively using the known hazards in the Wellington region, and the potential impact on the railway [17][18][19], and observations of performance in past earthquakes in New Zealand (the 2016 Kaikōura earthquake) [21] and overseas [20]. Where the railway route adjoining the road transport link was also likely to be closed in a future event for a long period, the criticality score was adjusted as follows:…”

Resilience of infrastructure networks

“…Subsequent earthquake reconnaissance visits to learn from earthquakes outside of New Zealand organised and led by the New Zealand Society for Earthquake Engineering and dissemination of the findings through lecture tours around New Zealand, such as after the 1994 Kobe earthquake in Japan [3], the 2008 Wenchuan earthquake [4] and the 2016 Kumamoto earthquake [5] provided additional information on the performance of lifeline infrastructure and impetus to lifelines studies and engineering. Lifelines groups were created around New Zealand following the examples set by Wellington and Canterbury, followed by the National Lifelines Council, which have co-ordinated the assessment and enhancement of lifeline infrastructure around New Zealand.…”

Seismic performance of non-structural elements (SPONSE) and Learning from earthquakes (LFE)

“…In addition to the special issues of the Bulletin published on recent New Zealand earthquakes (i.e. the 2010 Darfield earthquake, 2011 Christchurch earthquake and 2016 Kaikōura earthquake), it has also published reconnaissance reports on major overseas earthquakes including the 1985 Mexico earthquake [30], 2008 Wenchuan earthquake in China [31], 2009 Padang earthquake in Indonesia [32], 2015 Gorkha earthquake in Nepal [33], 2016 Kumamoto earthquake in Japan [34,35] and the 2016 Meinong earthquake in Taiwan [36]. Given the geological similarity between the soft lakebed in Mexico City and soft soil deposits in New Zealand cities, the ground motion characteristics and the building performance in this earthquake will be of significant interest to New Zealand earthquake engineers and seismologists.…”