Polygenetic sand volcanoes: On the features of liquefaction processes generated by a single event (2012 Emilia Romagna 5.9 Mw earthquake, Italy)

Sedimentology and composition of sands injected during the seismic crisis of May 2012 (Emilia, Italy): clues for source layer identification and liquefaction regime

“…The pulse mechanism of sand blows is also supported by the well stratified structure of the sand volcanoes that formed on the top of the fractures in many of the liquefaction sites around San Carlo ( and elsewhere, a feature described also by Rodríguez-Pascua et al (2015). These volcanoes are up to a few tens of centimeters high and show alternate cm-mm scale graded laminae consisting of sand and mud (Fig.…”

Liquefaction features at an archaeological site: Investigations of past earthquake events at the Early Christian Basilica, Ancient Lechaion Harbour, Corinth, Greece

“…Liquefaction is the transformation of cohesionless, saturated, loosely packed sediments from a solid to a liquid state as a result of increased pore pressure and reduced shear stress, leading to ground failures due to hydraulic fracturing (Obermeier & Pond, 1999, Obermeier, 2009, Rodríguez-Pascua et al, 2015. During earthquake shaking, liquefaction occurs in sediments such as silt, sand and gravel, originating at a depth ranging from a few meters to about 10 m below the ground surface (Obermeier, 1996).…”

“…The planar morphology and lateral distribution of the conduits suggest violent and episodic vertical displacements of the substratum, related to sudden and violent increase of the pore water pressure in the liquefied horizon through cyclic shear waves, leading to hydraulic fracturing of the overlying stratum (Obermeier, 2009, Rodríguez-Pascua et al, 2015. This hydraulic fracturing develops along lateral spreading zones, expressed through the surface depressions and buckling structures.…”

“…These Lateral spreading as indicated by the ERT profiles, was triggered along a shear zone located at approximately 4 to 5 m depth. This shear zone represents the liquefied horizon that through cyclic shear stress, induced hydraulic fracturing on the overlying strata and rapid upward drainage of the saturated deposits through extensional fissures, creating blocks that were transported downslope (Youd 1984a, Andrus 1986, Bartlett & Youd 1992, Obermeier et al, 2005, Rodríguez-Pascua et al, 2015.…”

Seismic palaeogeography of coastal zones in the Iberian Peninsula: Understanding ancient and historic earthquakes in Spain.

“…The localities of Almoradí and Benejúzar, placed in the eastern Muslin delta-lobe, were totally destroyed and rebuilt. A similar seismic scenario occurred during the recent EmiliaRomagna earthquake (Mw 6.2) in the Pianura Padanna (Southern Po Plain, Italy), where localities located on old river palaeochannels underwent strong seismic damage induced by liquefaction, widespread ejection of sand and water, repeated ground waving and sloshing (Emergeo, 2013, Rodríguez-Pascua et al, 2015. Figure 5 (3) illustrates the ESI-07 intensity zones corresponding to the AD 1829 Earthquake according to the documented building and environmental damage, compiled for the production of the Catalogue of Earthquake Geological effects in Spain (Silva and Rodríguez-Pascua, 2014).…”