Liquefaction Ejecta Case Histories for 2010-11 Canterbury Earthquakes

Abstract

Liquefaction ejecta damaged the land and light-weight residential houses during the 2010-2011 Canterbury earthquakes. A database of well-documented field case histories that can be used to develop a procedure to estimate the settlement due to ejecta does not currently exist. In this paper, 235 case histories that document the occurrence and quantity of ejecta and its effects on infrastructure at 61 sites for each of the four primary earthquakes of the Canterbury sequence are presented. The case histories were developed with access to the geotechnical database that includes thousands of CPTs and boreholes, airborne LiDAR surveys, aerial photographs, and detailed property inspection reports in Christchurch, New Zealand. Direct measurements of ejecta were not available; hence, the ejecta-induced settlement values were estimated using LiDAR- and photographic-based approaches. The information related to ground conditions and seismic demand leading to differing quantities of ejecta-induced settlement during the Canterbury earthquake sequence were also described. This database of detailed ejecta case histories can be used to investigate the occurrence and effects of ejecta and to develop procedures to estimate the quantity of ejecta produced due to liquefaction.