High Liquefaction Susceptibility Research Articles

Settlement Analysis in Potentially Liquifiable Soil at Kretek 2 Bridge Area

The Kretek 2 Bridge is one of the important infrastructures built on the southern coast road of Java. Referring to the Map of Indonesia Liquefaction Vulnerability Zone in 2019, Kretek 2 Bridge was identified as a high liquefaction susceptibility zone. The result of liquefaction potential analysis on the slab-on-pile section indicates that the soil layer has potential to liquefy if an earthquake occurs. Based on the Liquefaction Severity Index, the slab-on-pile section of the Kretek 2 Bridge has a high severity index at BH-10, moderate severity index at BH-11, and low severity index at BH-01 and BH-12. One of liquefaction effects is a ground settlement. Settlement due to liquefaction is a vertical soil deformation in the soil layer caused by compaction due to the earthquake. This study was conducted by calculating the settlement of sand deposits in slab-on-pile section using an equation proposed by Zhang et al. in 2002 and Yoshimine in 2006. The results of settlement analysis using Zhang’s method to predict settlement in the study area, BH-10 having the most significant settlement at 29.803 cm. Using the settlement analysis method by Yoshimine, the highest settlement found in BH-10, which is 30.401 cm.

A Detailed Liquefaction Susceptibility Map of Nestos River Delta, Thrace, Greece Based on Surficial Geology and Geomorphology

The existence of high potential onshore and offshore active faults capable to trigger large earthquakes in the broader area of Thrace, Greece in correlation with the critical infrastructures constructed on the recent and Holocene sediments of Nestos river delta plain, was the motivation for this research. The goal of this study is twofold; compilation of a new geomorphological map of the study area and the assessment of the liquefaction susceptibility of the surficial geological units. Liquefaction susceptibility at regional scale is assessed by taking into account information dealing with the depositional environment and age of the surficial geological units. In our case, available geological mapping shows a deficient depiction of Pleistocene and Holocene deposits. Taking into consideration the heterogeneously behavior of active floodplains and deltas in terms of liquefaction, a detailed classification of geological units was mandatory. Using data provided by satellite and aerial imagery, and topographic maps, dated before the 1970’s when extensive modifications and land reclamation occurred in the area, we were able to trace fluvial and coastal geomorphological features like abandoned stream/meanders, estuaries, dunes, lagoons and ox-bow lakes. This geomorphological-oriented approach clearly classified the geological units according to their depositional environment and resulted in a more reliable liquefaction susceptibility map of 4 classes of susceptibility; Low, Moderate, High and Very High. The sediments classified as very high liquefaction susceptibility are related to fluvial landforms, the high to moderate liquefaction susceptibility ones in coastal and floodplain landforms, and low susceptibility in zones of marshes. The sediments classified in the highest group of liquefaction susceptibility cover 85.56 km2 of the study area (16.6%). Particular attention was drawn to critical infrastructure (Kavala International Airport “Alexander the Great”) constructed on the most prone to liquefaction areas.

Liquefaction hazard assessment and ground failure probability analysis in the Kathmandu Valley of Nepal

During the 2015 Gorkha Earthquake (Mw7.8), extensive soil liquefaction was observed across the Kathmandu Valley. As a densely populated urban settlement, the assessment of liquefaction potential of the valley is crucial especially for ensuring the safety of engineering structures. In this study, we use borehole data including SPT-N values of 410 locations in the valley to assess the susceptibility, hazard, and risk of liquefaction of the valley soil considering three likely-to-recur scenario earthquakes. Some of the existing and frequently used analysis and computation methods are employed for the assessments, and the obtained results are presented in the form of liquefaction hazard maps indicating factor of safety, liquefaction potential index, and probability of ground failure (PG). The assessment results reveal that most of the areas have medium to very high liquefaction susceptibility, and that the central and southern parts of the valley are more susceptible to liquefaction and are at greater risk of liquefaction damage than the northern parts. The assessment outcomes are validated with the field manifestations during the 2015 Gorkha Earthquake. The target SPT-N values (Nimproved) at potentially liquefiable areas are determined using back analysis to ascertain no liquefaction during the aforesaid three scenario earthquakes.

Seismic Liquefaction Risk Assessment of Critical Facilities in Kathmandu Valley, Nepal

Kathmandu Valley lies in an active tectonic zone, meaning that earthquakes are common in the region. The most recent was the Gorkha Nepal earthquake, measuring 7.8 Mw. Past earthquakes caused soil liquefaction in the valley with severe damages and destruction of existing critical infrastructures. As for such infrastructures, the road network, health facilities, schools and airports are considered. This paper presents a liquefaction susceptibility map. This map was obtained by computing the liquefaction potential index (LPI) for several boreholes with SPT measurements and clustering the areas with similar values of LPI. Moreover, the locations of existing critical infrastructures were reported on this risk map. Therefore, we noted that 42% of the road network and 16% of the airport area are in zones of very high liquefaction susceptibility, while 60%, 54%, and 64% of health facilities, schools and colleges are in very high liquefaction zones, respectively. This indicates that most of the critical facilities in the valley are at serious risk of liquefaction during a major earthquake and therefore should be retrofitted for their proper functioning during such disasters.

Critical State Lines of Portuguese liquefiable sands

The Critical State framework has been used to describe the behaviour of sands and study the liquefaction susceptibility of these soils when sheared in static and cyclic conditions. The ocean coast and some fluvial basins of Portugal are characterised by the presence of sandy deposits that, combined with a moderate to high seismic activity, creates the conditions for moderate to high liquefaction susceptibility. The aim of this work is to study and compare five Portuguese liquefiable alluvial sands, collected in the centre-south of the continental territory. The experimental programme included a complete physical identification of the five materials and a series of triaxial tests in drained conditions. The specimens were prepared at a high initial void ratio (loose), using the moist-tamping technique with an appropriate initial water content, reaching void ratios close or slightly higher than emax. The specimens were fully saturated, isotropically consolidated and statically sheared at constant strain rate until reaching the critical state. Shear wave velocities after consolidation were measured using bender elements. The critical state and small-strain stiffness parameters are discussed and compared, evidencing the differences between these soils. Relationships between some of these parameters and physical characteristics are obtained.

Liquefaction susceptibility assessment in fluvial plains using airborne lidar: the case of the 2012 Emilia earthquake sequence area (Italy)

Abstract. We report a case study from the Po River plain region (northern Italy), where significant liquefaction-related land and property damage occurred during the 2012 Emilia seismic sequence. We took advantage of a 1 m pixel lidar digital terrain model (DTM) and of the 2012 Emilia coseismic liquefaction data set to (a) perform a detailed geomorphological study of the Po River plain area and (b) quantitatively define the liquefaction susceptibility of the geomorphologic features that experienced different abundance of liquefaction. One main finding is that linear topographic highs of fluvial origin – together with crevasse splays, abandoned riverbeds and very young land reclamation areas – acted as a preferential location for the occurrence of liquefaction phenomena. Moreover, we quantitatively defined a hierarchy in terms of liquefaction susceptibility for an ideal fluvial environment. We observed that a very high liquefaction susceptibility is found in coincidence with fluvial landforms, a high-to-moderate liquefaction susceptibility within a buffer distance of 100 and 200 m from mapped fluvial landforms and a low liquefaction susceptibility outside fluvial landforms and relative buffer areas. Lidar data allowed a significant improvement in mapping with respect to conventionally available topographic data and/or aerial imagery. These results have significant implications for accurate hazard and risk assessment as well as for land-use planning. We propose a simple geomorphological approach for liquefaction susceptibility estimation. Our findings can be applied to areas beyond Emilia that are characterized by similar fluvial-dominated environments and prone to significant seismic hazard.

Liquefaction of soil in the Emilia-Romagna region after the 2012 Northern Italy earthquake sequence

At the end of May 2012, the Po plain region in northern Italy was shaken by a long sequence of seismic events. The 2012 Northern Italy earthquake sequence counted two mainshocks, about 1,600 aftershocks and lasted for several weeks. Although the mainshocks, which occurred on May 20 and May 29, 2012, registered a moment magnitude of 5.9 and 5.8, respectively, these two events caused widespread soil liquefaction and substantial damages to the built environment. This paper reports lessons learnt from a field investigation conducted in the areas affected by the earthquake sequence. Based on the field observations, it was concluded that despite the relatively low magnitudes of the shocks, most of the damages occurred as a consequence of liquefaction phenomena and/or absence of retrofitting of historical structures. The latter comprise churches, tower bells, towers, castles and fortresses. It was found that the occurrence of liquefaction was mainly associated with the presence of saturated alluvial soil deposits which were characterised by high liquefaction susceptibility. It was noted that these highly liquefiable soils were mainly located in proximity of ancient river courses that were artificially diverted in the eighteenth century to mitigate flooding and other hydrological risks.

Liquefaction severity map for Aksaray city center (Central Anatolia, Turkey)

Abstract. Turkey having a long history of large earthquakes have been subjected to progressive adjacent earthquakes. Starting in 1939, the North Anatolian Fault Zone (NAFZ) produced a sequence of major earthquakes, of which the Mw 7.4 earthquake that struck western Turkey on 17 August 1999. Following the Erzincan earthquake in 1992, the soil liquefaction has been crucial important in the agenda of Turkey. Soil liquefaction was also observed widely during the Marmara and the Düzce Earthquake in 1999 (Sönmez, 2003). Aksaray city center locates in the central part of Turkey and the Tuzgolu Fault Zone passes through near the city center. The fault zone has been generated to moderate magnitude earthquakes. The geology of the Aksaray province basin contains Quaternary alluvial deposits formed by gravel, sand, silt, and clay layers in different thickness. The Tuzgolu Fault Zone (TFZ) came into being after the sedimetation of alluvial deposits. Thus, the fault is younger from lithological units and it is active. In addition, the ground water level is very shallow, within approximately 3 m from the surface. In this study, the liquefaction potential of the Aksaray province is investigated by recent procedure suggested by Sonmez and Gokceoglu (2005). For this purpose, the liquefaction susceptibility map of the Aksaray city center for liquefaction is presented. In the analysis, the input parameters such as the depth of the upper and lower boundaries of soil layer, SPT-N values, fine content, clay content and the liquid limit were used for all layers within 20 m from the surface. As a result, the category of very high susceptibility liquefaction class was not observed for the earthquake scenario of Ms=5.2, 4.9% of the study area has high liquefaction susceptibility. The percentage of the moderately, low, and very low liquefied areas are 28.2%, 30.2%, and 36.3%, respectively. The rank of non-liquefied susceptibility area is less than 1%.

Evaluasi awal kerentanan pelulukan/likuefaksi daerah Kendal dan sekitarnya, Jawa Tengah

http://dx.doi.org/10.17014/ijog.vol2no3.20074The investigated area is a region prone to liquefaction hazards since it consists of loose, saturated Quaternary deposits. The Quaternary deposits were deposited in several sediment environments such as swamp, estuary, near shore, off shore, and fluvial (flood plain, flood basin and paleo channel). Among those Quaternary deposits, the paleo channel and estuary deposits which mainly consist of fine - to medium - sand have high susceptibility to liquefaction. An earthquake-source zone which is able to trigger earthquake and to cause liquefaction hazards is known to be thrust fault and subduction zones. Earthquakes produced by thrust fault activities are classified as shallow earthquakes while earthquakes produced by a subduction zone are deep earthquakes. The investigated area is divided into low liquefaction susceptibility, moderate susceptibility and high liquefaction susceptibility zones. This division has been made based on physical characteristic of the sand deposits, grain size, thickness of sand and its position to groundwater level as well as the physical character of overburden layer.

Evaluasi awal kerentanan pelulukan/likuefaksi daerah Kendal dan sekitarnya, Jawa Tengah

http://dx.doi.org/10.17014/ijog.vol2no3.20074The investigated area is a region prone to liquefaction hazards since it consists of loose, saturated Quaternary deposits. The Quaternary deposits were deposited in several sediment environments such as swamp, estuary, near shore, off shore, and fluvial (flood plain, flood basin and paleo channel). Among those Quaternary deposits, the paleo channel and estuary deposits which mainly consist of fine - to medium - sand have high susceptibility to liquefaction. An earthquake-source zone which is able to trigger earthquake and to cause liquefaction hazards is known to be thrust fault and subduction zones. Earthquakes produced by thrust fault activities are classified as shallow earthquakes while earthquakes produced by a subduction zone are deep earthquakes. The investigated area is divided into low liquefaction susceptibility, moderate susceptibility and high liquefaction susceptibility zones. This division has been made based on physical characteristic of the sand deposits, grain size, thickness of sand and its position to groundwater level as well as the physical character of overburden layer.

Comparing Loss Estimation with Observed Damage in a Zone of Ground Failure: A Study of the 1999 Kocaeli Earthquake in Turkey

The building losses in Adapazari following the 17 August 1999 Kocaeli earthquake are estimated for both ground-shaking and ground-failure induced damage and the predictions compared with field observations. The ground-shaking damage is estimated using the capacity spectrum approach and accommodating the results of a previously published calibration of this model. These results, which do not incorporate ground-failure damage, are compared to the observed damage patterns in Adapazari to illustrate the significance of not including the more complex ground failure component in a loss model for a region of high liquefaction susceptibility. A preliminary estimation of ground-failure-induced damage is then presented based upon the HAZUS (FEMA, 2003) default methodology. The benefits of these additional calculations to the overall loss model are assessed to provide some quantitative decision-making guidance for those producing loss estimation models. The findings suggest that the benefits of specifically incorporating ground failure into a loss model only start to be obtained if a detailed approach using in situ geotechnical data as well as adequate representation of building foundations is adopted. Otherwise, the additional input data required is not commensurate with the small potential refinement in the estimated losses, particularly considering the compounded uncertainties associated with the simplified approach.

Historical Constraints on Previous Seismic Activity and Morphologic Changes near the Source Zone of the 1819 Rann of Kachchh Earthquake: Further Light on the Penultimate Event

The Kachchh (also spelled Kutch and Cutch) province in the northwestern part of India continues to be remarkably active seismically, the 2001 Bhuj ( Mw 7.7) earthquake being the most recent example of the region's seismogenic potential (Figure 1). Among past events, the 1819 earthquake ( M > 7.5) is well known and is quoted in the early geologic literature for the dramatic coseismic topographic changes associated with it, including the formation of the elevated tract of land called the Allah Bund (Lyell, 1857). Occurrence of two large earthquakes during a short span of 180 years gives an exceptional status to this seismic zone, considered to be part of the stable peninsular shield of India (Johnston, 1989). In addition to these, several moderate events are reported to have occurred in this region. These earthquakes are suggestive of the existence of multiple seismogenic faults in this region, but very little is known about their past histories, adding more uncertainty to the regional hazard assessment. Our search in the epicentral area of the 1819 earthquake led to the identification of another event between 800 and 1,000 years B.P. (Rajendran and Rajendran, 2001a). Based on the relative size and frequency of older sandblows, we interpreted that the earlier earthquake may have also originated from the same source. However, we recognize that isolating earthquake sources using paleoliquefaction features is not an easy task, particularly where large areas of high liquefaction susceptibility are affected by each event. The problem is more complex in regions where multiple sources exist. For example, until the occurrence of the 2001 earthquake, the Allah Bund region was the only known source of large earthquakes in the Kachchh region (Figure 2). Rajendran et al. , (2001) reported large sandblow craters formed by the Bhuj earthquake close to the 1819 source. If distant …

Three-dimensional interpolation and lithofacies analysis of granular composition data for earthquake-engineering characterization of shallow soil

In Japan, many major cities are located on tectonic basins which are surrounded by faults and underlain by soft alluvial materials. Because these areas are subject to earthquake damages, it is important to determine their seismic engineering characteristics. Geotechnical databases which contain many borehole logs are useful information sources for this type of analysis. Each datum stored in the database has a value or an attribute, and its location is irregular in both horizontal and vertical directions. A new interpolation method based on the optimization principle is proposed here to deal with such three-dimensionally distributed data. Susceptibility of unconsolidated ground to liquefaction is known to be related to the content of loose and saturated sand. The mixture ratio of several soil types in a deposit, i.e., granular composition, is strongly influenced by the sedimentary environment. There are two numerical methods: the optimization principle method (OPM) used to determine three-dimensional distribution of granular composition and the model used to evaluate liquefaction. The application of the proposed methods to two locations in Japan indicated that the zones with high susceptibility to liquefaction were indeed those that had suffered from liquefaction during past earthquakes.

Intensity of Earthquake Ground Motion at Liquefied Sites

The critical intensity of earthquake ground motion which separates liquefiable to non-liquefiable conditions is investigated. The peak ground acceleration and velocity are calculated at about 130 liquefied and non-liquefied sites during 19 Japanese earthquakes. These sites are on natural levee, river channel, reclaimed land or drained land, and have high liquefaction susceptibility. In the calculation, the effects of fault rupture and local site condition are considered, to obtain more accurate results than those in previous studies. The results of the calculation indicate that (1) the occurrence of soil liquefaction is better correlated with the peak ground velocity than with the peak ground acceleration, (2) soil liquefaction is likely to occur for the ground with high liquefaction susceptibility, when the peak ground velocity exceeds 15 kines (cm/s), and (3) the degree of soil liquefaction shows no clear correlation with peak ground velocity or acceleration.