Figure 3 - uploaded by Rosa Nappi
Content may be subject to copyright.
Examples of liquefaction produced by the 2012 Emilia sequence on the ground 636 and on manmade structures: a) detail of aligned multiple sand blows nearby 637 Fig. 3. Examples of surface phenomena produced by the 2012 Emilia sequence on the ground and on manmade structures: (a) detail of aligned multiple sand blows nearby Sant'Agostino; (b) ∼ 20 cm-wide open fracture with liquefaction near San Carlo. It is possible to observe several cm-wide, grey sand-filled cracks that represent the path to the surface of the liquefied material; (c) 30 mlong open fracture with massive ejection of dark grey sand in San Carlo (photo by L. Ghidoni); (d) fracture affecting the bridge over a channel filled with liquefied sand near Burana; (e) the warehouse of this pottery shop in San Carlo was covered by a ∼ 15 cm-thick layer of liquefied sands and silts; (f) liquefied sand filled this water well and poured out to cover a ∼ 500 m 2 circular area; (g) fracture affecting a paved road in San Carlo; (h) the ground/building limit often represented a preferential way of outflow for liquefaction, like in this case at San Felice sul Panaro.
Source publication
In this paper we present the geological effects induced by the 2012 Emilia seismic sequence in the Po Plain. Extensive liquefaction phenomena were observed over an area of �1200 km2 following the 20 May, ML 5.9 and 29 May, ML 5.8 mainshocks; both occurred on about E–W trending, S dipping blind thrust faults. We collected the coseismic geological ev...
Contexts in source publication
Context 1
... the basis of their morphologic and structural charac- teristics, the observed coseismic effects at the surface were grouped into three main categories (Fig. 3); (i) liquefac- tion: (ii) fracture/liquefaction; and (iii) fracture. Categories (i) and (ii) may be associated to relevant but localised sub- sidence or bulging related to sediments extrusion. Under the liquefaction category we classified single spots such as sand volcanoes, scattered vents and coalescent flat cones, sand infilled ...
Context 2
... 2012 Emilia seismic sequence hit a wide area of the southern Po Plain. Because of its high susceptibility to lique- faction of the alluvial plain, this seismic sequence produced the most prominent extensive liquefaction phenomena of the last century in Italy (Figs. 3, 4 and 5). The Emergeo Work- ing Group performed a systematic survey of the earthquake sequence area through field, aerial and interview approaches. A total of 1362 observation points were collected, stored in a geographical information system, and made partially avail- able at the address http://www.esriitalia.it/emergeo/. The ob- ...
Citations
... acoustic layer, which causes localized amplification and increases the severity of liquefaction within the valley. Although a more detailed subsurface study is required to understand the basin geometry and thickness of the quaternary deposits to include this effect in routine seismic hazard assessment, the basin effect was widely observed during several damaging earthquakes around the world, i.e., the 1985 Mexico city earthquake, 2008 Wenchuan earthquake, 2012 Emilia earthquake, 2015 Gorkha earthquake, 2016 Pohang earthquake (Pitarka et al., 1999;Pratt et al., 2003;Ergin et al., 2004;Alessio et al., 2013;Zeng et al., 2017;Naik et al., 2019, Porfido et al., 2020. Other factors might have added to the severity of liquefaction by trapping the seismic waves by the basin bounding faults surrounding the Assam valley (Fig. 7b). Figure 8 shows the distribution of the faults around the Assam valley that can trap the seismic waves within the block bounded by fault zones and significantly amplify the covering soft sediments within the basin. ...
On April 28 2021, an earthquake of MW 6.4 occurred near Sonitpur, Assam, India. The epicenter was 43 km away from
Tezpur, Assam with a focal depth of 34 km. The National Center for Seismology (NCS), Delhi reported the maximum intensity of
MMI–V whereas the United States Geological Survey (USGS) reported the maximum intensity of MMI–VII. Preliminary reports suggest a reverse slip component for the earthquake, which occurred close to the previously reported Kopili fault. This fault is the cause
of two damaging earthquakes in the past i.e., 1869 Cachar earthquake and the 1943 earthquake. The April 28 2021, Sonitpur earthquake
caused widespread liquefaction, building damage, and lateral spreading as far as 90 km from the epicenter. The present study reports
preliminary damages and ground effects observed soon after the earthquake along with a comparative analysis with previously
reported damages around the area during the historical earthquakes. The farthest reported liquefaction occurred during the earthquake
was plotted with other case studies which were well in agreement with the previous literature. The possible reason for the extensive
liquefaction and ground cracks is inferred to be due to site amplification within a sedimentary basin. Therefore, the occurrence of the
2021Sonitpur, Assam earthquake emphasizes the seismic hazard scenario for the Brahmaputra Basin and Bengal Basin, which further
requires more detailed study in terms of paleoseismology, liquefaction hazard zonation and seismic hazard assessment. In addition,
the damages to the buildings highlight the implementation of proper building codes considering the liquefaction hazard zonation map
for the study area.
... Several cases of soil failure and liquefaction manifestation have been reported in Southern Europe, for example, Montenegro, 1979 [2], and more recently, during the Emilia earthquake sequence in Italy in 2012 [3][4][5][6], the Kraljevo earthquake in Serbia in 2013 [7], the Durres earthquake in Albania [8][9][10], and the latest 2020 Petrinje earthquake in Croatia [11,12]. ...
Within the presented research, model tests were performed in 1-g conditions to investigate the liquefaction potential of Skopje sand as a representative soil from the Vardar River’s terraces in N. Macedonia. A series of shaking table tests were performed on a fully saturated, homogeneous model of Skopje sand in the newly designed and constructed laminar container in the Institute of Earthquake Engineering and Engineering Seismology (IZIIS), Skopje, N. Macedonia. The liquefaction depth in each shaking test was estimated based on the measured acceleration and pore water pressure as well as the frame movements of the laminar container. The surface settlement measurements indicated that the relative density increased by ~12% after each test. The observations from the tests confirmed that liquefaction was initiated along the depth at approximately the same time. The number of cycles required for liquefaction increased as the relative density increased. As the pore water pressure rose and reached the value of the effective stresses, the acceleration decreased, thus the period of the soil started to elongate. The results showed that the investigated Skopje sand was highly sensitive to void parameters and, under specific stress conditions, the liquefaction that occurred could be associated with large deformations. The presented experimental setup and soil material represent a well-proven example of a facility for continuous and sustainable research in earthquake geotechnical engineering.
... Among them, however, few studies considered worldwide liquefaction data such as [2,22], and the most recent year in the databases is 2003. While since 2003, there have been many cases of seismic liquefaction around the world such as the Colima earthquake in Mexico [27], the 2003 Bachu earthquake in China [12], the 2005 Muzaffarabad earthquake in Pakistan [20], the 2008 Wenchuan earthquake in China [11], the 2010-2011 Canterbury earthquake sequence in New Zealand [12], the 2011 Tohoku earthquake in Japan [12], the 2012 Emilia earthquake in Italy [1], the 2018 Songyuan earthquake in China [16], the 2020 Samos island earthquake in Greece [4,18], etc. These new data can greatly expand the database of liquefaction case histories with magnitude and distance. ...
... Moreover, on the one hand, since the M-D relations are sensitive to the considered case study, any new highquality observations will improve the relationships; on the other hand, the parameter uncertainty in the regression analysis will also affect the performance of the regression models. Thus, this study aims to (1) revise and extend the database of liquefaction case histories with different magnitudes and distances, (2) update the bounding equations using the Bayesian method based on the updated database for considering parameter uncertainty in regression models, (3) consider the effect of filed condition on the equations, and (4) compare the proposed equations with existing bounding equations to verify their effectivity. ...
Liquefaction-induced damage usually occurs in the epicentral area of earthquakes. To detect the maximum distance such as maximum epicentral distance (Remax), maximum fault distance (Rfmax), or maximum hypocentral distance (Rhmax) to cause damage given the magnitude of an earthquake, this study constructs multiple empirical models approximating the limiting distances (Remax, Rfmax, or Rhmax) as a function of different magnitudes (Mw, or Ms) using Bayesian regression method to consider model parameter uncertainty based on an updated global liquefaction database. The updated database with 290 cases is compiled from different historical earthquakes from 1117 to 2020, and these data cover the moment magnitude (Mw) from 4.6 to 9.5 and the maximum Remax from approximately 1 km to 480 km, which greatly expands the existing databases. The proposed magnitude-distance empirical relations in this study that can be useful in evaluating the minimum energy of an earthquake-induced liquefaction disaster or the maximum distance of the liquefied site given an earthquake in the rapid disaster mapping are more robust than other existing models. In these proposed models, the bounding equation in terms of Rhmax and Mw performs the best. In addition, the deposited condition of the site is also tried to be considered in the Mw–Rhmax model, which improved the performance of the model to a certain extent.
... Several ground-improvement solutions are available to mitigate the liquefaction hazard posed by clean sands, namely increasing the soil resistance by densification or reducing the earthquakeinduced excess pore pressures through drainage or reducing the shear strains through reinforcement. Vibratory compaction methods are a common and effective form of densification for cohesionless soils (Castro 1969), as proven by extensive research (e.g., D'Appolonia 1954;Mitchell 1981;Baez 1995;Adalier and Elgamal 2004;Wissmann et al. 2015;Vautherin et al. 2017;Amoroso et al. 2018). However, their effectiveness decreases as the fines content and plasticity increase (Mitchell 1981). ...
Following the 2012 Emilia-Romagna seismic sequence, widespread liquefaction of silty sands was observed, providing the opportunity to enhance our knowledge of the influence of fines content on seismic hazard and mitigation works. This paper presents the results of a thorough geotechnical investigation performed in connection with full-scale controlled blast tests in Bondeno, Italy, a small village that suffered liquefaction in 2012. Piezocone (CPTU) and seismic dilatometer (SDMT) tests were performed in natural and improved soils after rammed aggregate pier (RAP) treatment to a depth of 9.5 m to provide accurate soil characterization, evaluate liquefaction, and verify the effectiveness of the ground improvement. The combined use of piezocone (CPTU) and flat dilatometer (DMT) data provided reliable estimates of the overconsolidation ratio and at-rest earth pressure coefficient and highlighted the soil improvement in silty sands between 4 and 9 m in depth. Shear-wave velocity measurements showed a low sensitivity to RAP installation. The treatment effectiveness was also confirmed by the use of the simplified procedures for liquefaction assessment, underlining the important influence of the adopted fines profile and by the blast-induced liquefaction. CPTU and DMT parameters remained approximately unchanged between the piers after the detonation.
... Geotechnical, geological, geomorphological, and geophysical data were used to assess the quality of susceptible soil profiles to coseismic deformations, such as phenomenalinduced liquefaction including lateral spreading, sinkholes, sand boils, and ground subsidence [2,8,[59][60][61][62]. The thicknesses of the lithological units of the soil and the seismic shear wave profiles (assessed using the Nakamura method [63]) were analyzed using 23 available boreholes of up to 30 m deep; the number of SPT blows, granulometry, and water content were assessed in the soil, and variation in soil saturation degree, liquid limit (LL), and plas-Land 2022, 11, 463 4 of 20 ticity limit of soil strata samples were analyzed. ...
... Geotechnical, geological, geomorphological, and geophysical data were used to assess the quality of susceptible soil profiles to coseismic deformations, such as phenomenal-induced liquefaction including lateral spreading, sinkholes, sand boils, and ground subsidence [2,8,[59][60][61][62]. The thicknesses of the lithological units of the soil and the seismic shear wave profiles (assessed using the Nakamura method [63]) were analyzed using 23 available boreholes of up to 30 m deep; the number of SPT blows, granulometry, and water content were assessed in the soil, and variation in soil saturation degree, liquid limit (LL), and plasticity limit of soil strata samples were analyzed. ...
... (C n ) was calculated according to the equation proposed by Liao and Whitman (1986), i.e., C n = (Pa/σ' v )0.5 in function with (Pa) (atmospheric pressure) and the σ' v (effective vertical stress). Thereafter, a "fine content" correction was applied to the calculated N 1 (60) value in order to obtain an equivalent clean sand value (N 1 ) 60cs given by the equations proposed by Youd et al. (2001). ...
The city of Portoviejo in coastal Ecuador was severely affected during the April 16, 2016, Pedernales earthquake (Mw 7.8). Various co-seismic liquefaction phenomena occurred, inducing lateral spreading, sand boils, ground subsidence, and sinkholes in soils with poor geotechnical quality in the alluvial and alluvial–colluvial sedimentary environment. Therefore, the main aim of this study was to collect data from standard penetration tests (SPT) and shear velocity and exploratory trenches and to calculate the liquefaction potential index (LPI) by considering a corre-sponding seismic hazard scenario with an amax = 0,5 g. From these data, a liquefaction hazard map was constructed for the city of Portoviejo, wherein an Fs of 1,169 was obtained. It was de-termined that strata at a depth of between 8 and 12 m are potentially liquefiable. Our quantitative results demonstrate that the city of Portoviejo’s urban area has a high probability of liquefaction, whereas the area to the southeast of the city is less sensitive to liquefaction phenomena due to the presence of older sediments. Our results are in accordance with the environmental effects reported in the aftermath of the 2016 earthquake.
... However, fragility curves are constructed for areas affected by ground shaking and the ones affected mainly by ground failure. This is achieved by the use of alternative sources of information to determine the geographical extent of ground failure in each municipality (Alessio et al. 2012) and the proportion of buildings within these areas (i.e. using the 'Carta Tecnica Regionale', CTR, database). Having assessed the fragility of the buildings inventory, the fragility curves for the areas affected by ground shaking are compared with existing fragility curves which has been constructed either analytically (Verderame 2014; Kallioras et al. 2012) for similar buildings in Emilia-Romagna or empirically (Ioannou et al. 2020) for other Italian earthquakes and the results are discussed. ...
... Emilia-Romagna is located in the Po Plain between the Southern Alps and the northern Apennines. The alluvial origin of the soils in this area, and the presence of aquifers in the first 10 to 30 m depth, make the area susceptible to ground failure and in particular liquefaction (Alessio et al. 2012). A recent systematic study performed by the Emergeo Working Group (Alessio et al. 2012) identified the location of 1319 points of ground failure among the Emilia-Romagna municipalities (see Fig. 1). ...
... The alluvial origin of the soils in this area, and the presence of aquifers in the first 10 to 30 m depth, make the area susceptible to ground failure and in particular liquefaction (Alessio et al. 2012). A recent systematic study performed by the Emergeo Working Group (Alessio et al. 2012) identified the location of 1319 points of ground failure among the Emilia-Romagna municipalities (see Fig. 1). The data were collected through direct field survey and aerial photography, and showed liquefaction and fracture sites clustered in several areas. ...
In 2012, the Emilia-Romagna region in Italy was affected by ground shaking as well as widespread ground failure (mostly liquefaction) caused by a sequence of earthquakes. The fragility of the residential building inventory is empirically assessed here based on information from 39,087 buildings in 64 municipalities surveyed in order to assess their post-disaster usability. Key (and common) challenge with this type of large post-disaster databases is how best to treat the notable missing data error and address the non-representative sample. Fragility curves for buildings based on their construction material or age are constructed for areas affected by ground shaking and for areas ones affected by ground failure. As expected, old masonry buildings are the most vulnerable and reinforced concrete buildings are seen to be the least vulnerable. Both peak ground acceleration and peak ground velocity have been used to express the intensity measure type. Although, the former was found to fit the data best, it poorly predicted the probability of exceedance of extreme damage to ground failure for building classes associated with small sample sizes (e.g. RC buildings), highlighting the limitations of using non-representative samples in fragility assessment for extreme cases. The fragility curves for masonry buildings compare well with their counterparts based on existing empirical studies
... Liquefaction of subsurface sediment produces intrusive features such as sand dikes, sills, and blisters (defined as injected sediment partially vented at the surface by Villamor et al. (2014)) that disrupt the original soil stratigraphy, and extrusive features such as sand blows that form on the ground surface (Tuttle et al., 2018). Severe liquefaction can cause lateral spreading and subsidence, leading to significant changes to the landscape (Michetti et al., 2005;Audemard and Michetti, 2011;Hughes et al., 2015;Sassa and Takagawa, 2019) and disastrous effects on infrastructure, including critical facilities, pipelines, and road networks, as well as urban dwellings Bhattacharya et al., 2011;Emergeo, 2013;Huang and Yu, 2013;Cubrinovski et al., 2017a;Stringer et al., 2017). ...
... Between May and June 2012, an earthquake sequence struck the Emilia region in northern Italy, causing 26 fatalities as well as severe damage to historical centers and industrial areas, resulting in an economic loss of nearly 2 million Euros ($2.2 million US dollars). Main shocks of M w 6.1 and M w 5.9 took place on May 20 and 29, respectively (Caputo et al., 2016), and were followed by a number of aftershocks of local or Richter magnitude (M L ) greater than 5.1 (Emergeo, 2013). The 2012 Emilia earthquakes were caused by the reactivation of two segments of the Ferrara Arc thrust system, which represents the frontal portion of the buried Northern Apennines fold and thrust belt (Caputo et al., 2015). ...
... Following the 2012 ERES, three types of liquefaction features were documented on the Po Plain : individual and coalesced sand blows; elongated and aligned sand blows along open fractures; and fissures, without sand vented on the surface, often associated with a differential settlement or lateral spreading. Several groups of researchers described associations of liquefaction features with subtle geomorphic elements of the alluvial environment (Bertolini and Fioroni, 2012;Di Manna et al., 2012;Ninfo et al., 2012;Papathanassiou et al., 2012;Emergeo, 2013;De Martini et al., 2015). Civico et al. (2015) and De observed that 53% of all the features analyzed coincide with mapped fluvial landforms (Fig. 10), which represents only 15% of the entire study area. ...
Earthquake-induced liquefaction affects recent geologic deposits in undrained conditions resulting in ground failures that cause significant damage to the built environment. Early case studies of earthquakes that caused catastrophic liquefaction-related failures, including the 1897 India, 1811–12 New Madrid in the United States, 1964 Alaska in the United States, 1964 Niigata in Japan, and 1967 Caracas in Venezuela, drew attention to the phenomenon of liquefaction. Subsequently, geological and geotechnical studies contributed to the understand of the site conditions contributing to liquefaction, ground motions that initiate liquefaction, and the process of liquefaction. However, traditional ways of investigating liquefaction have often simplified subsurface geology and the depositional setting affected by liquefaction as a whole. Over the past several decades, studies of recent earthquakes that induced liquefaction, further progress has been made, including the development of (1) methodologies that provide a more accurate geological investigation of the affected region and (2) modelling tools that better integrate the methodologies. Future liquefaction susceptibility maps and hazard maps that utilize these methodologies and tools will reduce false predictions and contribute to more effective communication in liquefaction hazards. Lastly, paleoliquefaction investigations and paleoseismic findings are useful information for tectonic, especially neotectonics, studies in seismically active landscapes.
... It is induced by pore water pressure build-up, due to ground shaking, and can cause a significant reduction in the soil shear strength and stiffness as well as potential damage to existing structures. In turn, it may lead to economic and social losses, as with recent earthquakes (e.g., Christchurch, New Zealand, 2010Emilia, Italy, 2012) (Alessio et al., 2013;Stevenson et al., 2011, Bray et al. 2014). For such reasons, increasing attention has recently been given to the development of mitigation techniques against soil liquefaction. ...
Drainage is one of the most popular protecting measures to mitigate ground liquefaction. Deploying the drains horizontally may be convenient where conventional vertical ones cannot be used, like beneath existing structures. The spacing among drains must be designed to limit the pore pressure build-up during shaking. The usual assumptions of radial consolidation around vertical drains, stemming from the assumption of an infinite number of drains, may not be appropriate for horizontal ones, since the latter are generally arranged in few rows at a shallow depth, especially if drainage at the ground level is possible as well. Hence, existing solutions for vertical “earthquake” drains have been modified in this work to take into account such different geometrical features. The resulting solution has been validated against numerical and experimental sets of data. Charts covering a wide range of geometrical layouts, soil properties, and seismic actions are finally proposed. They can be used to design the drain spacing that is needed so as not to exceed the target value of excess pore pressure in the ground.
... During the 2012 Emilia earthquake (M w 5.9) in Italy, clustering of liquefaction features was observed with in the Po-Plain. This indicates that even if the affected area appears to be homogeneous from a geological point of view there are other local geological factors that controls the liquefaction susceptibility of the area within a basin or an alluvial plain [68][69][70]. Furthermore, previous studies [70,71] observed the mechanism involved in severe liquefaction within basins and suggested that the wedge shaped basement-to-sediment basin interface, which acted as acoustic lens, caused localized seismic wave amplification and extensive damage within the basin [7,[71][72][73][74][75]. ...
... It was suggested that large faults within the sedimentary basin with fault gouges, fractured rocks and fluids can trap the seismic waves within the block bounded by fault zones [5], which amplifies the upper bound in soft sediments of the basin. This amplification could be stronger within the basin surrounded by fault zones covered by unconsolidated Holocene alluvial deposits (Figures 11 and 12) [7,68,[80][81][82][83][84]. A similar observation was reported during the 2008 Wenchuan earthquake, where most of the liquefaction features were confined to the recent alluvial deposits close to the range front blind fault, and damaged buildings were clustered near or top of the Qingchuan blind fault in Sichuan province in China [7]. ...
On 15th November 2017, the Pohang earthquake (M w 5.4) had strong ground shaking that caused severe liquefaction and lateral spreading across the Heunghae Basin, around Pohang city, South Korea. Such liquefaction is a rare phenomenon during small or moderate earthquakes (M W < 5.5). There are only a few examples around the globe, but more so in the Korean Peninsula. In this paper, we present the results of a systematic survey of the secondary ground effects-i.e., soil liquefaction and ground cracks-developed during the earthquake. Most of the liquefaction sites are clustered near the epicenter and close to the Heunghae fault. Based on the geology, tectonic setting, distribution, and clustering of the sand boils along the southern part of the Heunghae Basin, we propose a geological model, suggesting that the Heunghae fault may have acted as a barrier to the propagation of seismic waves. Other factors like the mountain basin effect and/or amplification of seismic waves by a blind thrust fault could play an important role. Liquefaction phenomenon associated with the 2017 Pohang earthquake emphasizes that there is an urgent need of liquefaction potential mapping for the Pohang city and other areas with a similar geological setting. In areas underlain by extensive unconsolidated basin fill sediments-where the records of past earthquakes are exiguous or indistinct and there is poor implementation of building codes-future earthquakes of similar or larger magnitude as the Pohang earthquake are likely to occur again. Therefore, this represents a hazard that may cause significant societal and economic threats in the future.
... Liquefaction associated with recent seismic events has been highlighted in New Zealand (Ward et al. 2011), demonstrating the susceptibility of our environment to this potentially destructive process. Recent seismic events in Canterbury , Italy (Alessio et al. 2013) and Japan (Yasuda et al. 2012) have provided case studies, stimulating research into liquefaction susceptibility (Green et al. 2011(Green et al. , 2014 and its relationship to environments of deposition (Giona Bucci et al. 2017, 2018. ...
The Waitapu Shell Conglomerate is an important marker horizon in the eastern Whanganui Basin, occurring within a Pleistocene volcaniclastic record that contains early eruption products from the Taupo Volcanic Zone. The unit comprises a cross-bedded pebbly-shell conglomerate containing the first influx of Kaukatea Pumice (c. 0.9 Ma) within the Rangitikei succession. We document soft sediment deformation structures that occur in close stratigraphic proximity to the Waitapu Shell Conglomerate and other laterally equivalent units within the basins Castlecliffian outcrop belt. Soft sediment deformation structures formed through a combination of liquefaction and fluidisation, triggered by a range of mechanisms, including evidence of high sedimentation rates, loading, slope instability and potential for wave and earthquake-induced seismicity. Lateral changes in depositional style toward the basins eastern margin relate to relative position on the paleo-shelf, reduction of accommodation space, intermittent preservation of low stand deposits and proximity to the uplifting paleo-axial range.
