Geotechnical Engineering Online Library

The Canterbury Earthquake Sequence (2010 – 2011) caused significant damage and loss of life in Christchurch, New Zealand. The Earthquake Commission (EQC) is New Zealand’s public insurer for natural disaster damage. EQC determined that a new, claimable form of land damage had resulted due to the Increased Flooding Vulnerability (IFV) caused by the subsidence of the land changing the flood risk to residential properties. Tonkin & Taylor Ltd (T+T) on behalf of EQC had by early 2016 completed engineering assessments of over 11,000 residential properties in Canterbury. The purpose of the assessments was to understand and quantify the effects on residential properties of IFV caused by the Canterbury Earthquake Sequence. The completion of these assessments has involved over 75,000 man-hours and is the culmination of 5 years of data collection, policy and methodology development, legal and peer review. This paper examines some of the engineering challenges and how they were dealt with. It also considers what lessons could be learned if the process was to be repeated.

Safety of motorway users in case of a strong seismic event is directly related to the performance of infrastructure elements, especially motorway bridges. Preventive closure until post–seismic inspection may seem as the safest option, but will unavoidably lead to severe deterioration of serviceability, and will also obstruct the operations of rescue teams. On the other hand, allowing traffic on earthquake–damaged bridges without inspection may jeopardize the safety of users and rescue teams. Seismic retrofit is the obvious solution, but the associated costs can be quite substantial. An alternative strategy is to mitigate the indirect consequences of an earthquake, through timely development and implementation of a RApid REsponse (RARE) system. The scope of such a RARE system is to ensure the safety of motorway users, minimizing motorway network closure, and optimizing post-seismic recovery at the same time. The development of such a RARE system requires an effective means to estimate seismic damage in real time. This paper presents an overview of the RARE system and some first steps that were made regarding its pilot application in the Attiki Odos Motorway in Athens, Greece.

On the 16th of April 2016, the Kumamoto earthquake (Mw 7.0) hit the Central Kyushu Region, Japan, following a Mw 6.2 shock on the 14th of April. The earthquake sequences caused severe damage in Kumamoto Prefecture. This paper presents quick reconnaissance results focusing on geotechnical damage features, which were observed during field investigations immediately after, one, and two weeks after the main shock. The damage surveys were carried out in southern Kumamoto City, Mashiki Town, Aso Caldera area and their suburbs. In southern Kumamoto City, evidence of liquefaction was found at many locations, and some buildings and river levees suffered from significant settlement and deformation; damage to an embankment of Kyushu Highway also seemed to be the result of liquefaction. The majority of the damaged residential houses were found in Mashiki Town and its suburbs, which may be linked to intense earthquake motions associated with the seismic fault location. In Aso Caldera area, a number of moderate to large scale landslides and their significant impact to structures were observed. The greater part of landslide masses in Aso Caldera area was a mixture of volcanic ash, andsol, a highly porous dark-colored material comprising of volcanic ash mixed with organic matter, and pumice. These porous materials might have experienced significant strength reduction during the earthquake.

The L’Aquila earthquake occurred on April 6 2009 at 03:32:39 local time. The earthquake (Mw=6.3) was located in the central Italy region of Abruzzo. Much of the damage occurred in the capital city of L’Aquila, a city of approximate population 73000, although many small villages in the surrounding region of the middle Aterno river valley were also significantly damaged. In the weeks following the earthquake, the Geo-Engineering Extreme Events Reconnaissance (GEER) international team, comprised of members from different European countries and the U.S., was assembled to provide post-earthquake field reconnaissance. The GEER team focused on the geological, seismological, and geotechnical engineering aspects of the event. We describe the principal seismological findings related to this earthquake including moment tensors of the main shock and two triggered events, the aftershock pattern and its variation with time, tectonic deformations associated with the main shock, surface fault rupture, and the inferred fault rupture plane. We describe damage patterns on a village-to-village scale and on a more local scale within the city of L’Aquila. In many cases the damage patterns imply site effects, as neighbouring villages on rock and soil had significantly different damage intensities (damage more pronounced on softer sediments). The April 6 mainshock was the best-recorded event to date in Italy. We present metadata related to the recording sites and then present preliminary comparisons of the data to GMPEs. Those comparisons support the notion of faster distance attenuation in Italy relative to the average for active regions as reflected in NGA GMPEs. Several incidents of ground failure are then discussed, including a number of rockfalls and minor landslides. Perhaps the most significant incidents of ground failure occurred at Lake Sinizzo, for which we describe a number of slumps and spreads around the lake perimeter. This is documented using field observations as well as LIDAR and bathymetric data.

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.