Messina Strait Research Articles

Geodetic surveys across the Messina Straits (southern Italy) seismogenetic area

The Messina Straits, southern Italy, unfortunately became famous after the occurrence of the great earthquake of December 28, 1908, Ms = 7.5, that caused thousands of deaths and severe destruction over a wide area along the Sicilian and Calabrian coasts. After that time many geophysical and geological studies were performed to evaluate the seismic characteristics of the 1908 earthquake, the seismic risk and the geological evolution of this region in the framework of Mediterranean geodynamics. In 1970, a geodetic network was set up across the Straits and was repeatedly measured with terrestrial techniques until 1980, showing a northward displacement of the Sicilian sites with respect to the Calabrian ones, between 1970 and 1971. In 1987, the old terrestrial network was surveyed again for the first time by the GPS technique, improving the accuracy of the coordinate determinations. Finally, in 1994, a wider network was established and surveyed again to collect additional GPS observations from a larger area across the Straits. In this paper, an analysis of the results obtained from the two GPS surveys with respect to those achieved by the terrestrial surveys (from 1970 to 1980) is given. This analysis shows there has not been significant crustal horizontal deformation across the Straits in the last 15 years. Although this crustal tectonic ‘quiescence’ corresponds to a low seismic activity level in the Straits area, terrestrial and GPS geodetic results would agree with Straits geophysical models excluding any aseismic deformations acting perpendicular to the Straits axis.

Crustal stress regime in Italy

In order to obtain a reliable map of the present-day stress field in Italy, needed to better understand the active tectonic processes and to contribute to the assessment of seismic hazard, in 1992 we started to collect and analyze new data from borehole breakouts in deep oil and geothermal wells and focal mechanisms of earthquakes (2.5 < M <5) occurred in Italy between 1988 and 1995. From about 200 deep wells and 300 focal mechanisms analyzed to date, we infer that: the internal (SW) sector of the Northern Apenninic arc is extending with minimum compressional stress (Shmin) oriented ? ENE, while the external front is thrusting over the Adriatic foreland (Shmin ? NW-SE). The entire Southern Apennine is extending in NE direction (from the Tyrrhenian margin to the Apulian foreland) and compression (in the foredeep) is no longer active at the outer (NE) thrust front. Between these two arcs, an abrupt change in the tectonic regime is detected with directions of horizontal stress changing by as much as 90º in the external front, around latitude 430N. Along the Ionian side of the Calabrian arc the stress directions inferred from breakouts and focal mechanisms are scattered with a hint of rotation from N-S Shmin close to the Southern Apennines, to ~ E-W directions in the Messina Strait. In Sicily, a NW-SE direction of SHmax is evident in the Hyblean foreland, parallel to the direction of plate motion between Africa and Europe. A more complex pattern of stress directions is observed in the thrust belt zone, with rotations from the regional trend (NW í directed SHmax) to NE oriented SHmax. A predominant NW direction of SHmax is also detected in mainland Sicily from earthquake focal mechanisms, but no well data are available in this region. In the northern part of Sicily (Aeolian Islands) a ~N-S direction of SHmax is observed.

The impact of mega‐infrastructure projects on urban development—Boston and the Messina Straits

The hypothesis of our research project in comparative urban development is that while large infrastructure projects impact the local economy, labour markets and the environment, the interactive response and linkages of the players may cancel benefits when project development and implementation are done without a proper planning framework. Empirically we consider the impact of the implementation of the artery‐tunnel project in Boston, Massachusetts, USA and the proposed fixed link over the Straits of Messina, Italy (the metropolitan area of Messina and Reggio Calabria). While the two areas vary in population, income and existing infrastructure, the impacts are similar in kind and are proportional in the same direction. The distortions derived from the lack of overall urban economic and physical planning are evident from the review of abundant partial studies, some rich in analytical content, but disconnected with the events in impacted space. Growing environmental issues, as well as economic change, call for regional, comprehensive, consistent, long‐sighted public planning.

Earthquakes in medieval Sicily. A historical revision (7th-13th century)

The need to understand the activity of the main seismogenetic structures, to calculate the recurrence periods of major earthquakes and to identify their main epicentral areas, requires wide-ranging research in the field of historical seismology. The present research was conducted in the framework of the projects of the Istituto Nazionale di Geofisica (1991-1995). The presence of different populations and ruling elites, and hence of languages and cultures, has in many cases confused the historical context of the medieval Sicilian sources. However, by going beyond the local sources, and analysing the events in a wider European and Mediterranean context, taking due account of the Byzantine, Latin and Arab sources, it has been possible to identify five seismic events that do not exist in the Italian catalogues or whose dates are very difficult to establish. Six spurious events have been deleted thanks to the revision (659, 785, 796, 963, 1069, 1259); the date of an event has been corrected (1140 into 1125) and five unknown events have been discovered: 853, 1172, 1203-1204, 1255-1256 and 1295-1296. The data on which these findings are based are in many cases dispersed and unused within the many specialised sectors of historical research; in some cases they are unknown even to historians. An example of textual analysis of the sources is also presented to show by what a roundabout route the chronological parameter for the 1125 earthquake was reached. The new events confirm the high seismicity of the eastern area of Sicily; nevertheless, the newly identified series does not seem to show any seismic event comparable to the one that struck the Messina Strait, in 1908 (I0 = XI MCS, M = 7.2): this historical element can provide information regarding the return times of such great event; a hypothesis is formulated by the authors: it will have to be carefully examinated by archaeology research. The criteria used in this research are explained, as well as the problems tackled in accordance with the method for the revision of the historical earthquakes adopted by ING-SGA.

New Records of Albunea Carabus (L., 1758) (Decapoda, Anomura) in the Mediterranean Sea

Four adult males and one ovigerous female of Albunea carabus were taken during quantitative sampling carried out in the northern area of the Messina Straits. This is the first record of the species for the southern Tyrrhenian Sea. The substratum was identified as the Biocoenosis of Coarse Sand and Fine Gravels under Bottom Currents (SGCF, Peres & Picard, 1964) and hypotheses on the species' habitat are discussed. Finally, new data on the maximum size of the species are provided.

Finite-element simulations of the 5 February 1783 Calabrian tsunami

Southern Calabria is one of the Italian coastal regions mostly affected by tsunami hazard. This work is a part of a wider study of the assessment of the tsunami hazard in the southern Calabria and eastern Sicily. The tsunami which we focus our attention on was the first of a series of events that were associated with the 1783 Calabrian seismic crisis that was one of the most catastrophic affecting southern Italy in historical times. The tsunami was generated by an I=XI earthquake: the isoseismal field is elongated in the direction of the Apennine chain and centered in the Gioia Tauro plain where the most relevant damage was reported. Several numerical simulations of the tsunami have been performed by means of a finite-element method based on the shallow-water equations with different sources. The Tyrrhenian sea facing southern Calabria, including the Messina Strait, has been covered by a triangle-based mesh. The numerical results, compared with the available historical observations, such as the polarity of the first arriving wave, the mean wave period, etc. enable us to evaluate the most reliable source mechanisms and locations.

Application of Sponheuer and Blake models in the seismic hazard evaluation: the case of Messina Straits : E. Stillitani, A. Bottari, A. Teramo & M. Pietrafesa, Geofizica, 10, 1993, pp 35–46

Application of Sponheuer and Blake models in the seismic hazard evaluation: the case of Messina Straits : E. Stillitani, A. Bottari, A. Teramo & M. Pietrafesa, Geofizica, 10, 1993, pp 35–46

PRELIMINARY DESIGN OF THE MESSINA STRAIT BRIDGE.

Although it is only 25 years since the feasibility of a fixed-link between Sicily and the Italian mainland, what will be the world's longest span bridge is now high on Italy's political agenda. The heavy traffic expected, coupled with the fast-moving waters of the Messina Strait, and also the seismic risk in the area, led to the decision to site the suspension towers on land. The paper details the preliminary design for the suspension bridge, design criteria, history and site investigations.

The aerodynamic design of the Messina Straits Bridge

The challenge towards larger spans, one of the most fascinating in the whole history of structural engineering, shall see several milestones laid before the end of this decade, with the construction of bridges breaking the one-mile limit and nearly touching the two kilometers. The knowledge underlying such advancements shows fully in the final design for a single span suspension bridge of 3300 m across the Messina Straits, which shall link Sicily to the mainland in Italy. Wind effects are dominant in the behaviour of such long and slender structures: after a discussion of related suspension bridge evolution aspects, the lines followed for the Messina Bridge case are presented, together with the bulk of experimental and numerical analyses that accompanied, guided and validated the design concepts.

Aeroelastic behaviour of long span bridges with “multibox” type deck sections

The truss and box classical bridge deck sections, together with several proposed modifications, seem to be not applicable to “very” long span bridges, like the Messina Strait Bridge, for which multibox type section has been proposed.Even if this concept has been validated analytically and experimentally, yet not much has been done for understanding the basic principles of its aerodynamic and aeroelastic behaviour and the effects of some design parameters on its critical wind speeds.The main goal of this paper is to give a further contribution to these aspects, using well-known methods and computer programs widely used in the aeronautical research and design field. The preliminary results of these studies relative to steady aerodynamics and classical flutter behaviour are encouraging. It has been possible to evidence some interesting parameters that influence considerably the flutter speed for which it could be useful to define the sensitivity of the critical wind speed to this parameter variations.

Rapid uplift, stepped marine terraces and raised shorelines on the Calabrian coast of Messina Strait, Italy

AbstractA series of 26 Quaternary shorelines, stepped between present sea level and 556 m, are studied. They are part of the flight of marine terraces of the Aspromonte region. The shorelines were determined using three geomorphological models: wave‐cut platforms and gravel‐built terraces associated with their sea‐cliff foot, and observations of lateral changes between marine terraces and fluvial terraces. The elevation of the sea‐cliff foot is either measured directly, by exposure in cross‐section, or by estimation from geomorphological patterns. With caution, we connect the different landmarks of the shorelines which are discontinuous because of destruction between interfluves or because they are overlain by torrential deposits.The results of mapping show that there are few differential movements from one transect to another and mean uplift rate is 98 cm ka−1. This rate is calculated on the basis of a correlation of the area studied with the Ravagnese Tyrrhenian site, 125 m high, whose date is isotopic substage 5e. Middle and Late Quaternary tectonic activity leads to faulting, slight folding and warping but some scarps associated with faults are actually ancient sea cliffs.

Discussion of SEI 2/92

The article Strait Crossing (IRRD 855154) stimulated some sharp reactions from readers, including the assertion that the proposed bridge-tunnel was not feasible. In this discussion contribution, two dissenters argue against the proposal, and the author replies. Dimitrov and Duleski note that a bridge-tunnel approach was investigated for the crossing of the Messina Strait, but was abandoned because of insurmountable difficulties. They claim that Braino's article (IRRD 855154) presented no calculations supporting the possibility of the Gibraltar bridge- tunnel. They present the results of rough calculations for a circular 35m diameter tube with a 2.5m thick reinforced concrete wall. They conclude that the stresses on such a tube and its resulting deflections would be impossible for any known techniques to handle. In his reply, Braino admits some lack of clarity in Fig. 2 of his article, but considers that his design is 'possible' in the sense that its specific functions, conditions, and parameters can be specified and designed individually. He gives some additional information, stating that his completed feasibility study answers criticisms of his design and provides evidence that it is preferable. He is willing to provide more details on request.

Frequency dependence of site amplification factor in the Messina Strait area

The spectral ratio method is used here for evaluating the frequency dependence of a site amplification factor in the Messina Strait area. All stations exhibit the same features of spectral ratios evidencing two peaks at about 10 Hz and 16 Hz. We relate this observation to the same geological structures. In fact, all the stations (except the referenced one) are situated over pleistocenic sediments with a similar grain size. This causes the disappearing of any site effect when the average spectrum is used as a reference. MES station, situated in the city of Messina, presents a clear site effect at a different frequency (6 Hz) which cannot be related to any geological structure because no substantial difference is observed between the sediments on which this station is situated and the sediments on which the other stations are situated. MT1 station exhibits a spectral peak at about 2 Hz which can be explained with oscillations of a little sedimentary basin.

Wind measurements on Messina straits

A research concerning the wind characteristics on Messina Straits has been carried out by Stretto di Messina SpA and Politecnico di Milano inside the project of Messina Bridge. For this purpose a meteo station has been collecting meteorological data since 1985 at Punta Faro near Messina. Transducers, located on the two towers of the ENEL HV transmission line between the Sicily and the mainland (fig. 1), measure wind speed and direction (SE/ZE, GILL), air temperature (TE) and humidity (ME), quantity of rain (LE), sun radiation (XE) and atmospheric pressure (PE). All the wind data useful to value the dynamic behaviour of the bridge to aero-elastic forces are preserved.

Fault parameters in the Messina Strait (southern Italy) and relations with the seismogenic source

The Messina Strait is characterized by strong deformations in Pliocene and Pleistocene times, but considering the historical seismicity, significant uncertainity exists as to whether any of the surface fault systems reflects the location, geometry and mechanisms of the seismogenic source. Based on field data and structural analyses, the parameters length ( L), displacement ( D), age of activity ( T), minimum slip rate (μ min) and total geological moment ( M g) have been derived for all the faults exposed on the Sicilian and Calabrian sides of the Strait. The analysis of these parameters shows that the highest rates of activity pertain to interconnected faults of different orientation and length, which bound the uplifted crystalline basement relative to the Pliocene-Pleistocene foundered zones of the Calabrian side. The comparison between the fault slip rates and the regional uplift rates shows that each single fault contributes for a limited fraction only to the whole deformation release in the area. The contribution of the whole fault population expressed as cumulative M g release is still one order of magnitude less than the seismic moment release. Taking into account the underestimation of the geological parameters, the lack of information on the offshore faults, and the role of anelastic deformation by aseismic creep, the data suggest that the long-term recurrence of seismic breaks is partitioned at the surface in a complex array of interconnected faults. Some of these faults might represent basement-inherited structures, repeatedly and preferentially reactivated over geological time.

Depth dependence of seismic attenuation in the Messina Strait area

The attenuation structure of the Messina strait area is studied using the single-scattering model of coda wave generation. Data are short-period seismograms belonging to a swarm occurring in the middle of the Messina strait (Italy). The coda- Q appears to be frequency dependent following the empirical law Q = Q 0 ƒ n , with Q 0 and n depending on the coda duration interval. A strong lapse time dependence of Q c (coda- Q) is found. This dependence is interpreted as a depth effect, in the sense that longer codas sample deeper portions of the lithosphere. A simple geometrical model is used to infer from the lapse time dependence in a layered Q-structure of the crust and upper lithosphere. Our results are compared with those obtained in other tectonically active and non-active areas, showing that the inferred Q-structure can be used as a tectonic indicator.

A 125 Kyr‐long geological record of seismic source repeatability: the Messina Straits (southern Italy) and the 1908 earthquake (Ms 71/2)

ABSTRACTThe occurrence of characteristic earthquakes along segments of major active belts has been described as early as the beginning of the century. The large 1908, Messina Straits, blind normal faulting earthquake provides an opportunity to investigate the repetition of characteristic earthquakes and the persistency of the main features of the fault zone over a time‐scale in the order of 100 Kyr. We have compared seismological and geodetic descriptions of the 1908 rupture process with long‐term crustal deformation recorded at different stratigraphic levels by marine terraces, marine sedimentary units, and landscape features. The wealth of elevated coastal features in and around a region affected by large normal faulting earthquakes indicates that coseismic strain is superimposed on much faster uplift on a regional scale. We investigated in detail the pattern of deformation of the 125 Kyr‐old, lowest emergent terrace, and found that it mimics the pattern of elevation changes observed following the earthquake. This suggests (1) that the 1908 earthquake is characteristic, (2) that its segment boundaries have been stationary during the past 125 Kyr, and (3) that even the locations of the regions of largest coseismic release do not change through many seismic cycles. Based on a comparison between observed heights of the 125 Kyr terrace and 1908 displacements, we estimated an average repeat time of 1000± yr for a 1908‐type earthquake. We also investigated the height, position, age and state of deformation of older terraces, and found (1) that uplift of the region started about 1 Ma and has since continued rather uniformly at 0.9–1.4 mm yr‐1, (2) that during this time the Straits have narrowed at a rate of 10–20 mm yr‐1, and (3) that all the main geomorphic features of the Messina Straits result from the interaction of fast regional uplift, 1908‐type coseismic subsidence, and global sea‐level fluctuations.

A Variable Slip Fault Model For the 1908 Messina Straits (Italy) Earthquake, By Inversion of Levelling Data

SUMMARY A variable slip fault model is presented for the 1908 December 28 Messina (Italy) earthquake. It has been obtained by inversion of levelling data, using a gradient method. Fault location and mechanism are consistent with an approximately N-S orientation and normal faulting on a low-angle plane dipping 39°, with about 45° of strike-slip component. The main difference from a homogeneous slip model is represented by a higher slip area (up to 3 m), located close to the city of Reggio Calabria. It is interpretable as a major asperity, which is related to the main fracture episode. This is in agreement with some macroseismic evidence and the same structure could be responsible for the nearby recent seismic activity. The area which effectively slipped is all confined within the Messina straits. This result differs from the homogeneous slip model recently proposed by Capuano et al. (1988).

Assessment of tsunami hazard in the Italian seas

A method for the evaluation of tsunami potential in the seas surrounding Italy is presented. A major difficulty for performing reliable estimates of tsunami occurrence is that the existing tsunami catalog for Italy includes a small number of cases. This is due partly to the catalog incompleteness, strangely more pronounced in our century, and partly to the relative infrequency of tsunamis along the Italian seas. Evaluation of tsunami activity is therefore deduced by complementing the tsunami catalog data with data on seismicity that are by far more abundant and reliable. Analysis of seismicity and assessment of earthquake rate in coastal and submarine regions form the basis of the present method to perform tsunami potential estimates for Italy. One essential limitation of the method is that only tsunamis of seismic origin are taken into account, which leads to an underestimation of the tsunami potential. Since tsunamis generated by earthquakes are much more frequent than events produced by slumps or volcanic eruptions, the underestimation is not dramatic and very likely affects only a limited portion of the Italian coasts. In the present application of the method, eight separate regions have been considered that together cover all the coasts of Italy. In each region, seismicity has been independently examined and the earthquake potential has been calculated in small 20′ × 20′ cells. Then, on the basis of suitable assumptions, tsunami potential has been evaluated in each cell. According to this study, the Italian coasts that are the most exposed to the attacks of locally generated tsunamis are to be found in the Messina Straits, in Tyrrhenian coasts of Calabria, in the Ionian Sicilian coasts around Catania, and in the Gargano promontory in the Southern Adriatic Sea. Furthermore, this study confirms that the Northern Adriatic Sea has a low level of tsunami potential, in agreement with recent studies emphasizing that the large historical events concerning this region included in the first versions of the Italian tsunami catalog are largely overestimated and must be decreased.

Lignicolous marine fungi in the Straits of Messina, Italy

The occurrence and distribution of lignicolous marine fungi in the Straits of Messina has been studied. Using submerged panels of pine, beech and poplar, twenty fungal species were identified. The lignicolous mycoflora of the Messina Straits was not significantly different from that reported in the literature for other temperate marine coastal environments, Ascomycotina being frequent, while Basidiomycotina were rare.