RAPID: Liquefaction and its Effects on Buildings and Lifelines in the 2010-2011 Canterbury, New Zealand Earthquake Sequence

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

This Grant for Rapid Response Research (RAPID) award provides funding to investigate liquefaction and its effects on buildings and lifelines in the 2010-2011 Canterbury, New Zealand earthquake sequence with the goal of capturing perishable data that would lead to the development of enhanced analytical procedures for evaluating the hazard holistically. The 2010-2011 Canterbury, New Zealand earthquake sequence started with the Mw7.0, 4 September 2010 Darfield earthquake that occurred to the west of Christchurch and included 3 events having ML >=6.0 and 45 events having ML >=5.0. Because of its close proximity to Christchurch and shallow depth of fault rupture, the Mw6.2, 22 February 2011 Christchurch earthquake was the most devastating event in the sequence, resulting in nearly 200 deaths and thousands of injuries, with widespread liquefaction and damage to the built environment. This earthquake sequence provides a unique opportunity to evaluate in considerable depth the effects of earthquake shaking of different intensities on the response of various soil profiles, and the effects of liquefaction on building foundations and critical lifeline systems. This research has three main thrusts: (1) re-occurrence of liquefaction; (2) building performance in areas of liquefaction; and (3) lifeline performance in areas of liquefaction-induced ground failure. Significant accomplishments were made in each of these areas in a previous RAPID effort. However, as is often the case in research, in performing the previous investigations additional significant, time-critical opportunities to advance the knowledge of geotechnical and lifeline earthquake engineering were identified. There is still much to learn from comparing the different levels of soil liquefaction caused by the earthquakes in this sequence and from evaluating the differing seismic performance of buildings, lifelines, and engineered systems during these events. It is extremely rare to have the opportunity to learn how the same ground and infrastructure responded to multiple earthquakes having different levels of shaking intensities. Furthermore, the magnitude and distances of the Darfield and Christchurch earthquakes are two of the scenarios often considered in US cities. Capturing details of lateral spreads and the impacts of liquefaction on well-built structures, such as office buildings and their interconnecting buried utilities, are critically important. Field reconnaissance will be focused on capturing perishable data and characterizing the soil profiles at select sites. This study will be coordinated through the GEER Association and performed in collaboration with the University of Canterbury (i.e., Professors Misko Cubrinovski, Brendon Bradley, and Mark Quigley) and the New Zealand government. This proposal requests the funding necessary for carefully documenting the perishable data in as much detail as possible. The broader impacts of this stem from documenting and learning from observations after design level earthquakes, which are invaluable to advancing the state-of-practice in earthquake engineering. Surveying the re-occurrence of liquefaction, documenting cases of liquefaction-induced ground movements, and evaluating the effects of liquefaction on buildings and lifelines advances fundamental understanding of earthquake effects and develops benchmarks for future analysis and design. The Darfield and Christchurch earthquakes, in particular, represent important earthquake scenarios for the U.S. Thus, there is a real need to document their geotechnical effects. Moreover, these earthquakes involve multi-hazard effects. The combined settlement caused by liquefaction during both earthquakes has exposed many Christchurch neighborhoods to increased threats from river and ocean flooding, including tsunami. Collection of data on liquefaction-induced ground movement will form the basis for flood risk assessment as well as earthquake vulnerability. The proposed study combines the efforts of several leading researchers to examine the effects of liquefaction holistically. The team also includes graduate students; this research will help develop their capabilities in earthquake engineering and allow them to establish research contacts in New Zealand. This award is co-funded by the Office of International Science and Engineering, East Asia and Pacific Program.