On the origin of multiple tsunami inundation of the archaeological site of Ognina (Sicily): Numerical models and field geological data

Author(s):  
Giovanni Scardino ◽  
Angela Rizzo ◽  
Vincenzo De Santis ◽  
Despo Kyriakoudi ◽  
Alessio Rovere ◽  
...  

<p>South-eastern Sicily is among the most seismically active areas of the central Mediterranean. As such, it is marked by a high level of crustal seismicity producing major earthquakes (up to Mw ∼7), and consequent several earthquake-generated tsunami, which have affected the Ionian coast of South-eastern Sicily in historical times. These tsunami events left geomorphic imprints such as large boulders or high-energy deposits along the Sicily coasts. In Ognina, a small town located 20 km south of Siracusa, high-energy deposits were correlated with three tsunami events that struck this coast on 21 July 365 Common Era (CE), 4 February 1169 CE, and 11 January 1693 CE. The deposits are detected in the inner part of a narrow channel, that is thought to have funnelled the tsunami flow energy. In this work, numerical models have been performed to simulate the tsunami impacts, considering the most probable tsunamogenic sources described in literature and integrating them with the past sea-level positions. To this end, we used Delft Dashboard, Delft 3d-FLOW and XBeach. A reconstruction of the past topography of Ognina coast was performed through geological and historical information, in order to model the tsunami wave propagation in the ancient landscape. Geological evidence with model results, under different scenarios, allow us to benchmark fault location and displacement scenarios. Modelling results indicate that the 1693 tsunami event was stronger than others impacting the Ognina area, determining significant inland flooding in the narrow channel. Moreover, simulations show that the most probable tsunamogenic sources of 1693 and 1169 tsunami events could be attributed to Western Fault dislocations occurred off-shore of Ognina area, rather than the other tsunamogenic sources described in literature, located off-shore of Catania and Siracusa. Modelling of 365 AD event shows a long period for the tsunami wave that determined the sedimentation on the lower units in the outcrop. For each of the three tsunami events, models of high-energy deposition match with position and thickness of high-energy layers detected in the field. The results of this study show how a combined approach between geological evidence and tsunami modelling could be a suitable tool for the attribution of tsunami deposits connected to specific tsunamogenic sources.</p><p> </p><p>Keyword: tsunami; earthquake; faults; flooding; sea-level</p>

2018 ◽  
Vol 18 (7) ◽  
pp. 1985-1998 ◽  
Author(s):  
Francesc Xavier Roig-Munar ◽  
Joan Manuel Vilaplana ◽  
Antoni Rodríguez-Perea ◽  
José Ángel Martín-Prieto ◽  
Bernadí Gelabert

Abstract. Large boulders have been found on marine cliffs of 24 study areas on Minorca, in the Balearic archipelago. These large imbricated boulders of up to 229 t are located on platforms that comprise the rocky coastline of Minorca, several tens of meters from the edge of the cliff, up to 15 m above the sea level and kilometers away from any inland escarpment. They are mostly located on the south-eastern coast of the island, and numerical models have identified this coastline as a zone with a high probability of tsunami impact. The age of the boulders of the studied localities range between 1574 AD and recent times, although most of them are concentrated around the year 1790 AD. Although some storm waves might play a role in their dislodging, the distribution of the boulder sites along the Balearic Islands, the degree and direction of imbrication and the run-up necessary for their placement suggest transport from northern African tsunami waves that hit the coastline of Minorca.


2019 ◽  
Author(s):  
Yu Sun ◽  
Riccardo E. M. Riva

Abstract. The effect of Glacial Isostatic Adjustment (GIA) on the shape and gravity of the Earth is usually described by numerical models that simultaneously solve for glacial evolution and Earth's rheology, being mainly constrained by the geological evidence of local ice extent and global sea level, as well as by geodetic observations of Earth's rotation. In recent years, GPS and GRACE observations have often been used to improve those models, especially in the context of regional studies. However, consistency issues between different regional models limit their ability to answer questions from global scale geodesy. Examples are the closure of the sea level budget, the explanation of observed changes in Earth's rotation, and the determination of the origin of the Earth's reference frame. Here, we present a global empirical model of present-day GIA, solely based on GRACE data and on geoid fingerprints of mass redistribution. We will show how the use of observations from a single space-borne platform, together with GIA fingerprints based on different viscosity profiles, allows us to tackle the questions from global scale geodesy mentioned above. We find that, in the GRACE era (2003–2016), freshwater exchange between land and oceans has caused global mean sea level to rise by 1.5 ± 0.3 mm/yr, the geocentre to move by 0.5 mm/yr, and the Earth's dynamic oblateness (J2) to increase by 6.7 × 10−11/yr.


2020 ◽  
Vol 11 (1) ◽  
pp. 129-137
Author(s):  
Yu Sun ◽  
Riccardo E. M. Riva

Abstract. The effect of glacial isostatic adjustment (GIA) on the shape and gravity of the Earth is usually described by numerical models that solve for both glacial evolution and Earth's rheology, being mainly constrained by the geological evidence of local ice extent and globally distributed sea level data, as well as by geodetic observations of Earth's rotation. In recent years, GPS and GRACE observations have often been used to improve those models, especially in the context of regional studies. However, consistency issues between different regional models limit their ability to answer questions from global-scale geodesy. Examples are the closure of the sea level budget, the explanation of observed changes in Earth's rotation, and the determination of the origin of the Earth's reference frame. Here, we present a global empirical model of present-day GIA, solely based on GRACE data and on geoid fingerprints of mass redistribution. We will show how the use of observations from a single space-borne platform, together with GIA fingerprints based on different viscosity profiles, allows us to tackle the questions from global-scale geodesy mentioned above. We find that, in the GRACE era (2003–2016), freshwater exchange between land and oceans has caused global mean sea level to rise by 1.2±0.2 mm yr−1, the geocentre to move by 0.4±0.1 mm yr−1, and the Earth's dynamic oblateness (J2) to increase by 6.0±0.4×10-11 yr−1.


2012 ◽  
Vol 12 (4) ◽  
pp. 1185-1200 ◽  
Author(s):  
F. Gerardi ◽  
A. Smedile ◽  
C. Pirrotta ◽  
M. S. Barbano ◽  
P. M. De Martini ◽  
...  

Abstract. Analysis of tsunami deposits from the Pantano Morghella area provided geological evidence for two inundations occurred along the south-eastern Ionian coast of Sicily. Pantano Morghella is a large pond characterised by a fine-grained sedimentation indicating a low-energy depositional environment. Two anomalous yellow sandy layers found at different depths indicate the occurrence of high-energy marine inundations. We studied sedimentological and paleontological features of the anomalous deposits as well as their spatial distribution observing the following properties: different facies with respect to the local stratigraphic sequence; erosive bases, rip-up clasts and broken elements testifying violent deposition mechanisms; macro and micro fauna of marine environment; relatively constant thickness throughout most of the depositional zone with thinning at the distal end; large sand sheets that extend inland. These observations, jointly with their infrequency in the sedimentary record and the age indicating a fast deposition, provided strong evidence for tsunami inundations. Correlations between anomalous layers and historical tsunamis are supported by radiocarbon and OSL dating results. The younger deposit is likely due to the 1908 near-source tsunami, whereas the flooding of the oldest event is most likely associated with a far and large source, the Crete 365 AD earthquake.


2011 ◽  
Vol 1 (32) ◽  
pp. 25
Author(s):  
Maja Fickert

Among all consequences of climate change the expected global sea-level rise will have the greatest impact on seaborne navigation and maintaining the seaports. Also for coastal protection planning the knowledge of current sea-level rise is essential. A hind cast of the global numerical models for the climate scenarios especially for the sea level data is hardly to perform precisely because time series of uneffected sea level data are too short and include no regional aspects. With the knowledge of the sea-level rise in the past and a detection of an accelerated rise the results and predictions of numerical models can be underlined.


Author(s):  
Zening Lin ◽  
Tao Jiang ◽  
Jianzhong Shang

Abstract In the past few decades, robotics research has witnessed an increasingly high interest in miniaturized, intelligent, and integrated robots. The imperative component of a robot is the actuator that determines its performance. Although traditional rigid drives such as motors and gas engines have shown great prevalence in most macroscale circumstances, the reduction of these drives to the millimeter or even lower scale results in a significant increase in manufacturing difficulty accompanied by a remarkable performance decline. Biohybrid robots driven by living cells can be a potential solution to overcome these drawbacks by benefiting from the intrinsic microscale self-assembly of living tissues and high energy efficiency, which, among other unprecedented properties, also feature flexibility, self-repair, and even multiple degrees of freedom. This paper systematically reviews the development of biohybrid robots. First, the development of biological flexible drivers is introduced while emphasizing on their advantages over traditional drivers. Second, up-to-date works regarding biohybrid robots are reviewed in detail from three aspects: biological driving sources, actuator materials, and structures with associated control methodologies. Finally, the potential future applications and major challenges of biohybrid robots are explored. Graphic abstract


2012 ◽  
Vol 84 (3) ◽  
pp. 411-423 ◽  
Author(s):  
Pietro Tundo

Since the Industrial Revolution, chlorine has featured as an iconic molecule in process chemistry even though its production by electrolysis of sodium chloride is very energy-intensive. Owing to its high energy and reactivity, chlorine allows the manufacture of chlorinated derivatives in a very easy way: AlCl3, SnCl4, TiCl4, SiCl4, ZnCl2, PCl3, PCl5, POCl3, COCl2, etc. in turn are pillar intermediates in the production of numerous everyday goods. This kind of chloride chemistry is widely used because the energy is transferred to these intermediates, making further syntheses easy. The environmental and health constraints (toxicity and eco-toxicity, ozone layer depletion) and the growing need for energy (energy efficiency, climate change) force us to take advantage from available knowledge to develop new chemical strategies. Substitution of chlorine in end products in compounds where “chlorine is used in the making” means that we avoid electrolysis as primary energetic source; this makes chemistry “without chlorine” considerably more difficult and illustrates why it has not found favor in the past. The rationale behind this Special Topic issue is to seek useful and industrially relevant examples for alternatives to chlorine in synthesis, so as to facilitate the development of industrially relevant and implementable breakthrough technologies.


2011 ◽  
Vol 62 (3) ◽  
pp. 223 ◽  
Author(s):  
Allison Aldous ◽  
James Fitzsimons ◽  
Brian Richter ◽  
Leslie Bach

Climate change is expected to have significant impacts on hydrologic regimes and freshwater ecosystems, and yet few basins have adequate numerical models to guide the development of freshwater climate adaptation strategies. Such strategies can build on existing freshwater conservation activities, and incorporate predicted climate change impacts. We illustrate this concept with three case studies. In the Upper Klamath Basin of the western USA, a shift in land management practices would buffer this landscape from a declining snowpack. In the Murray–Darling Basin of south-eastern Australia, identifying the requirements of flood-dependent natural values would better inform the delivery of environmental water in response to reduced runoff and less water. In the Savannah Basin of the south-eastern USA, dam managers are considering technological and engineering upgrades in response to more severe floods and droughts, which would also improve the implementation of recommended environmental flows. Even though the three case studies are in different landscapes, they all contain significant freshwater biodiversity values. These values are threatened by water allocation problems that will be exacerbated by climate change, and yet all provide opportunities for the development of effective climate adaptation strategies.


2021 ◽  
Author(s):  
A. Rita Carrasco ◽  
Katerina Kombiadou ◽  
Miguel Amado

<p>It is predictable that salt marshes in regions, where sediment loads are high, should be stable against a broader range of relative sea level scenarios than those in sediment-poor systems. Despite extensive theoretical and laboratory studies, additional syntheses of marsh ‘persistence’ indicators under human interventions and accelerated sea-level rise rates are still needed. This study investigates the recent lateral changes occurring in lagoon-type marshes of the Ria Formosa lagoon (south Portugal) in the presence of human interventions and sea-level rise, to identify the major drivers for past marsh evolution and to estimate potential future trends. The conducted analysis assessed the past geomorphological adjustment based on imagery analysis and assessed its potential future adjustment to sea-level rise (~100 years) based on modelled land cover changes (by employing the SLAMM model within two sea-level rise scenarios).</p><p>Salt marshes in the Ria Formosa showed slow lateral growth rates over the last 70 years (<1 mm∙yr<sup>-1</sup>), with localized erosion along the main navigable channels associated with dredging activities. Higher change rates were noted near the inlets, with stronger progradation near the natural inlets of the system, fed by sediment influx pulses. Any potential influence of sea-level increase to an intensification of marsh-edge erosion in the past, could not be distinguished from human-induced pressures in the area. No significant sediment was exchanged between the salt marshes and tidal flats, and no self-organization pattern between them was observed in past. The related analysis showed that landcover changes in the salt marsh areas are likely to be more prominent in the future. The obtained results showed evidence of non-linearity in marsh response to high sea-level rise rates, which could indicate to the presence of critical thresholds and potential negative feedbacks within the system, with significant implications to marsh resilience.</p>


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