Geotechnical Engineering Online Library

Macroseismic observations in the meizoseismal area of the Achaia-Ilia, Greece, Mw 6.4 earthquake of 8 June, 2008, have shown that soil liquefaction occurred at a number of sites up to distances of 25 km from the causative fault. In one of these sites (SITE-I at coastal zone of Kato Achaia) the occurrence of liquefaction was extensive and was followed by lateral spreading. In another nearby site (SITE-II) only marginal liquefaction (or nonliquefaction) was observed. Following the macroseismic observations, a geotechnical investigation was carried out at SITE-I and SITE-II which included exploratory boreholes with continuous sampling, SPT measurements, CPT soundings, surface wave measurements (SASW, MASW, ReMi) and laboratory testing. Based on the results of geotechnical investigation, the soil stratigraphy and pertinent soil properties were evaluated in the liquefaction/nonliquefaction locations. The assessment of peak ground acceleration at the area of SITE-I and SITE-II was based on attenuation relations and shaking table tests performed to simulate the observed behavior of an overturned (during the main shock), barrel-shaped, plastic, water filled container sitting on the ground surface at SITE-I. It is believed that the data presented in this paper can be used to 1) check the validity of current liquefaction susceptibility criteria/liquefaction triggering relationships, and 2) establish a well documented liquefaction case history that can be part of future liquefaction databases.

The collapse of the Showa Bridge during the 1964 Niigata earthquake features in many publications as an iconic example of the detrimental effects of liquefaction. It was generally believed that lateral spreading was the cause of failure of the bridge. This hypothesis is based on the reliable eye witness that the bridge failed 1 to 2 minutes after the earthquake started which clearly ruled out the possibility that inertia (during the initial strong shaking) was the contributor to the collapse. Bhattacharya (2003), Bhattacharya and Bolton (2004), Bhattacharya et al (2005) reanalyzed the bridge and showed that the lateral spreading hypothesis cannot explain the failure of the bridge. The aim of this short paper is to collate the research carried out on this subject and reach conclusions based on analytical studies and quantitative analysis. It is being recognised that precise quantitative analysis can be difficult due to lack of instrumented data. However, as engineers, we need to carry out order-of-magnitude calculations to discard various failure hypotheses.

Two strong earthquakes shook the Island of Hawaii, Hawaii on the morning of October 15, 2006. Peak Ground Accelerations reached 1.2g, and earthquake felt intensity of MMI VIII. Earthquake damage of public and private property totaled about $200 million, with no fatalities. Geological engineering reconnaissance of earthquake damage resulting from the earthquakes focused on the apparent relationships between the observed geology and the damage. Some roadway embankments failed causing temporary closure of Island highways. Landslides were common at steep coastal cliffs. Liquefaction and lateral spreading occurred in coralline fill at Kawaihae Harbor. There were extensive road cut failures, in which the performance of road cuts in soil slopes was generally better than that of rock slopes. Where a’a clinker underlay massive a’a basalt blocks in road cut slopes, the loose clinker dislodged thereby undermining the blocks, and causing failures that blocked important roads. There was serious damage to stacked rock edifices such as the Hawaiian ritual temples of Pu’ukoholā and Mailekini. There are some parallels between the geomechanical behavior of clinker rock masses and the behavior of stacked rock structures: slope angle, slope height, particle size and nature and proportion of inter-particle contacts govern the seismic performance for both.