A team of four civil engineers sponsored by ASCE’s Technical Council on Lifeline Earthquake Engineering traveled to Sichuan Province, China, May 27–28 to investigate and report on a U.S. Geological Survey-estimated 6.6 magnitude earthquake that struck there on April 20.
This latest earthquake ruptured a segment of the fault system that in 2008 had produced the Wenchuan 7.9-magnitude earthquake—which according to Chinese state officials left almost 70,000 people dead, more than 18,000 missing, and nearly 375,000 injured. The more than 100 dams damaged by the Wenchuan earthquake had, like most of the structures in the area, been constructed before 1976, thus were not built to an adequate design code and so could not withstand the earthquake.
Last April’s Sichuan earthquake resulted in significantly less loss of life and damage—more than 200 people were reported killed and at least 12,000 injured. However, power systems were devastated, telecommunications disrupted, highways damaged by landslides, and many if not all local roadways destroyed.
In planning its work, the ASCE/TCLEE team set out to answer these consequential engineering questions:
- Were there any seismic upgrades to existing buildings between 2008 and 2013?
- Were emergency response activities in 2013 particularly useful in limiting casualties or improving restoration of service?
- Were the lessons learned from the 2008 earthquake actually implemented?
- Have any updates to the building code been adopted and implemented?
- Have the power and utility companies upgraded their lifeline systems in the 5 years between the 2 earthquakes? If so, how, and were the changes effective?
- What standards or practices are used in lifeline construction and when were these systems constructed?
“The answers to these questions will provide ASCE members and U.S. disaster management officials with insights into building codes and standards application in design and construction,” explained Alex K. Tang, P.E., F.ASCE, one of the four members of the ASCE/TCLEE team that traveled to Sichuan. “This event gave our ASCE team the opportunity to critically evaluate and apply lessons learned or possibly lessons ignored since the 2008 earthquake event.”
Other members of the team included team leader John Eidinger, P.E., M.ASCE; Craig Davis, P.E., M.ASCE; and Tao Lai, Ph.D.
“Basically what our team did was look at the performance of the lifelines, which we defined as telecommunication, wastewater, electric power, gas and liquid fuel, and transportation such as bridges, roadways, and railways,” says Tang, who is also a member of the ASCE/TCLEE Earthquake Investigation Technical Committee. “We also looked at facility damage, like buildings that house the equipment: for example, communication offices or water purification processing plants.”
Lessons Learned, Lessons Ignored
Tang notes that with each recent major earthquake—Turkey (1999), New Zealand (2010), and Japan (2011) —there was increased loading on adjacent fault segments, resulting in a second major earthquake occurring within the next six months to five years.
“This important observation seems to be consistently ignored by building officials, emergency planners, and structural engineers,” says Tang, who was leader of the ASCE/TCLEE reconnaissance team to Christchurch, New Zealand, in April 2011. That magnitude 6.3 earthquake occurred six months after a 7.1-magnitude earthquake struck 6.2 miles to the east of Christchurch.
Specifically, the China team visited three rural communities hit hardest by the earthquake: Lushan, Ya’na, and Foci Rock. The team spent two days examining the communities’ seismic code, geotechnical and geologic hazards, water and wastewater systems, electrical power systems, bridges, buildings, hospitals, and schools.
“We did see improvement in some areas,” suggests Tang. “For example, [Lushan Yan] Hospital comprises four buildings and the [one] most recently constructed after the 2008 earthquake was isolated [from the others]. That means that the strong shaking [from the earthquake] did not affect the building at all and it survived. That is the good news.
“The other three buildings did not survive and they had to clear everybody out and move everybody into the one surviving building. Because there was no flexibility to allow building movement [during the earthquake], many of the lifelines were broken, like water pipes and sewers and things like that. So hopefully with the rebuilding [of the other three hospital buildings] they are putting in some flexibility in order to avoid any future damage.”
Tang says the information gathered by this reconnaissance team is useful for policymakers in smaller communities in the U.S. at risk of earthquakes.
“This compares favorably to what would happen if an earthquake struck a U.S. community that is within an earthquake zone, such as the coastal cities of Oregon,” says Tang.
Second Major Mission Goal
A second major focus of the team was to document the occurrence of geotechnical landslides and other related phenomena in China. This information could be very important for dealing with earthquakes that might occur in the Sierra Nevada mountains of California, the coastal ranges of Oregon and Washington states, and other mountainous areas and their effects on rivers and hydroelectric dams in the area.
“We found there were extensive landslides, rock falls, and things like that, which damaged bridges and roads, making travel very, very difficult,” says Tang. “I think it is very important for transportation engineers to think about building a redundant network, because in China when there is only one major roadway going through a community, it makes rescue and repair very hard.
“In fact, the Chinese had to use military helicopters to fly in to do the repair. Now, maybe we can learn from that.”
Currently, TCLEE is updating Monograph 11 (Guide to Post-Earthquake Investigation of Lifelines). TCLEE Monograph 11 contains information such as anchoring requirements for various equipment, equipment installation, practices observed, and material of pipelines that can be compared with previous earthquake investigation. Tang says that what the team learned in the field in China could be a good reference for the best practices in design and installation to reduce earthquake damages.
All of TCLEE’s post-earthquake investigation monographs have the peak ground accelerations and failure modes of various lifelines, which can be an excellent starting point for a pre-standard document.
“Right now, our team is also putting together an addendum that is going to be incorporated into the Wenchuan Monograph,” says Tang. “We are planning to present a session, workshop, or webinar, at one of ASCE’s upcoming conferences on why communities do not mitigate for the next big disaster, and what regulators can do to issue cost-effective building codes soon after a big disaster.
“We were very encouraged about the fact that there is some progress made in regard to lifelines and improving the earthquake protection in China,” Tang says. “It may be slow because it is a rural community and may not be getting the necessary resources, but it is happening.”