Eugenio Turco

Active tectonics in the central Apennines and possible implications for seismic hazard analysis in peninsular Italy

Abstract The central Apennines fault system (CAFS) of peninsular Italy, overprints earlier structures of a Neogene fold and thrust belt and includes segments characterized by diffuse seismicity distributed within a NNW-SSE-trending zone, 50–60 km wide. The system has been analysed by means of morphotectonic and structural analysis of exposed active fault segments. The resulting fault structure consists of an interconnecting network of roughly N-S-trending, left-lateral, strike-slip segments and mostly NW-SE-oriented, transtensional to normal faults. Evidence for recent activity of CAFS structures is provided by faulted Middle Pleistocene-Holocene deposits (including 30–40-ka-old pyroclastites and 40-ka-old palustrine sediments), fresh scarps in both bedrock and Late Quaternary continental deposits, and decametric lateral offsets locally affecting the post-Wurmian drainage pattern of the area. The regional stress field responsible for the development and evolution of the CAFS, as inferred from fault slip data, is characterized by a NW-SE compression and by a NE-SW extension. The CAFS pattern and its present-day kinematics have been related to left-lateral strike-slip motion on north-south-trending crustal faults. The existence of deep-seated strike-slip faults in the central Apennines has implications for seismic hazard analysis. Motion along these structures suggests, in fact, that coseismic surface faulting is distributed, and that cumulative displacements include normal, transtensional, and strike-slip components. The seismogenic potential of CAFS structures can therefore be best described by multiple-rupture models and be better analysed in terms of partial contributions of lower-rank features constituting congruent structural associations within the system.

Tectonic history of the western Tethys since the Late Triassic

The tectonic history of the western Tethys since the Late Triassic is illustrated through a set of computer-generated plate reconstructions, which are based on a rigorous plate motions model of this region. The model is constrained by the Atlantic plate kinematics and on-land geologic evidence and defines 13 tectonic phases, spanning the time interval from the late Ladinian (230 Ma) to the present. The kinematics associated with the Late Triassic western Tethyan rifts produced the detachment of a large composite fragment from the northern margin of Gondwana. It can be considered as the eastern propagation of the central Pangea breakup. During the Early Jurassic these rift zones became inactive, while new zones of extension formed along the southern margin of Eurasia, the eastern margin of Iberia, and within the rifted northern Gondwana fragment itself. Plate motions associated with the first two extensional centers can still be considered as an eastern branch of the central Atlantic plate kinematics. Conversely, the kinematic parameters of the latter rift result from the composition of the Euler rotation describing the central Pangea breakup and the Euler pole of closure of the paleo–Tethys ocean. The Late Triassic–Early Jurassic rifting phases determined the formation of a number of independent microplates at the interface between Africa and Eurasia. Starting from the Early Cretaceous, convergence between Africa and Eurasia triggered further deformation within the dispersed continental fragments and the formation of backarc basins at the active margins, ultimately leading to an increase in the number of tectonic elements that were moving independently in the western Tethyan region during the Late Cretaceous and the Cenozoic. The proposed tectonic evolution of the western Tethys area is compatible with both global-scale plate kinematics and geological constraints from on-land data observed across the present-day mosaic of displaced terranes surrounding the Mediterranean region.

Geometry of the neotectonic stress field in southern Italy: Geological and seismological evidence

The neotectonic regime in southern Italy has been evaluated by making a comparison between all the available structural and seismological data. The area investigated can be subdivided into four distinct zones which are characterized by different stress regimes. In the Southern Apennines the tensile axis of the stress field is oriented approximately NE-SW while the maximum principal stress (σ1) is subvertical. In Northern Calabria, the tensile axis is ESE-WNW and the σ1 axis is almost vertical. In the Catanzaro trough both the tensile axis and the σ1 axis are subhorizontal and act E-W and N-S, respectively. Finally, the Strait of Messina zone is characterized by a tensile axis oriented E-W and by σ1 being subvertical.

Quaternary faults and seismicity in the Umbro-Marchean Apennines (Central Italy): evidence from the 1997 Colfiorito earthquake

Abstract Analyses of structural and geomorphological data combined with remote sensing interpretation confirm previous knowledge on the existence of an extensional Quaternary tectonic regime in the Colfiorito area (Umbro-Marchean Central Apennines). This is characterized by a maximum principal axis of finite strain oriented approx. NE–SW, which is the result of a progressive deformation process due to pure and radial extension. Surface geological data, the crustal tectonic setting (reconstructed using a CROP 03 seismic reflection profile), and seismological data relative to the autumn 1997 Colfiorito earthquake sequence constrain the following seismotectonic model. We interpret the seismogenic SW-dipping low-angle normal fault pictured by seismic data as an inverted thrust ramp located in the basement at depth between 5 and 10 km. The surface projection of this seismogenic structure defines a crustal box within which high-angle normal faults are responsible for the deformation of the uppermost crust. The regional patterns of pre-existing basement thrusts therefore control the seismotectonic zoning of the area that cannot be directly related to the high-angle normal fault systems which cut through different crustal boxes; the latter system records, in fact, re-shear along pre-existing normal faults. Moreover, Quaternary slip-rates relative to high-angle normal faults in the Central Apennines are closely related to seismic hazard within each crustal box.

p140Cap dual regulation of E-cadherin/EGFR cross-talk and Ras signalling in tumour cell scatter and proliferation

The adaptor protein p140Cap/SNIP is a novel Src-binding protein that regulates Src activation through C-terminal Src kinase (Csk). Here, by gain and loss of function approaches in breast and colon cancer cells, we report that p140Cap immobilizes E-cadherin at the cell membrane and inhibits EGFR and Erk1/2 signalling, blocking scatter and proliferation of cancer cells. p140Cap-dependent regulation of E-cadherin/EGFR cross-talk and cell motility is due to the inhibition of Src kinase. However, rescue of Src activity is not sufficient to restore Erk1/2 phosphorylation and proliferation. Indeed, p140Cap also impairs Erk1/2 phosphorylation by affecting Ras activity, downstream to the EGFR. In conclusion, p140Cap stabilizes adherens junctions and inhibits EGFR and Ras signalling through the dual control of both Src and Ras activities, thus affecting crucial cancer properties such as invasion and growth. Interestingly, p140Cap expression is lost in more aggressive human breast cancers, showing an inverse correlation with EGFR expression. Therefore, p140Cap mechanistically behaves as a tumour suppressor that inhibits signalling pathways leading to aggressive phenotypes.

Chapter 2 The Pleistocene extension of the Campania Plain in the framework of the southern Tyrrhenian tectonic evolution: morphotectonic analysis, kinematic model and implications for volcanism

Abstract The Tyrrhenian margin of the Apennine chain (TMAC) experienced widespread extensional tectonics characterized by volcanism and the formation of several marine and intermontane troughs and basins in Pleistocene times. The Campania Plain is part of this extensional system, which encompasses an area from southern Tuscany to the northern margin of Calabria. Extensional tectonics affecting these continental areas is likely to be related with the final stages of the opening of the southern Tyrrhenian Sea, which developed since Middle Tortonian times. This work presents a quantitative kinematic model explaining the relationships between extension in the Tyrrhenian Sea, basin formation in the TMAC, migration of the Apenninic arcs and geotectonic setting of the volcanism. A synthesis of the volcanic, structural and geophysical data available in the literature, coupled with a detailed morphotectonic analysis of the study areas were used in computer-aided reconstruction techniques based on interactive modelling of rigid block rotations to realistically assemble in a unique kinematic framework the first-order structures that are observed in the Apennines area and in the Tyrrhenian basin. Once established, the extension directions in the various sectors of the Apennine chain, by comparing the results of the morpho-structural analysis with data collected from the abundant geological literature, we identified two distinct kinematic elements characterizing the Apennine chain that, from Plio-Pleistocene times, moved independently with respect to the Eurasian reference plate: the Northern Apennines Arc (NAA) and the Southern Apennines Arc (SAA). On the basis of the first-order geological and goephysical constraints, as well as on trial and error experiments, we identified two distinct rotation stages for the Apennine chain. During the first stage, from 3.5 to 0.78 Ma, the NAA and the SAA migrated independently. In the second stage, from 0.78 Ma to the present, the NAA stopped migrating, while the SAA continued migrating towards SE. Thus, N-S extension in the Campania Plain is the result of the relative motion of the NAA with respect to the SAA during the first stage only, whereas the present-day NW-SE extension in this area, which is characterized by intense volcanism (e.g. Ignimbrites, Somma-Vesuvio, Ischia, Campi Flegrei), is related to the migration towards the SE of the SAA with respect to the NAA. The simplifying assumption of rigidity of the two arcs does not substantially affect the model presented, which only aims at describing the process of extension and associated magmatic activity in the TMAC. Furthermore, the model presented above could not take into account many aspects of the complex tectonic evolution of the TMCA. Nevertheless, it realistically assembles in a unique kinematic framework the first-order structures that are observed in the Apennine area and in the Tyrrhenian basin.

p140Cap suppresses the invasive properties of highly metastatic MTLn3-EGFR cells via impaired cortactin phosphorylation.

We have recently shown that the adaptor protein p140Cap regulates tumor properties in terms of cell motility and growth. Here, by using the highly metastatic rat adenocarcinoma cell line MTLn3-epidermal growth factor receptor (EGFR), we assess the role of p140Cap in metastasis formation. Orthotopic transplantation of MTLn3-EGFR cells over-expressing p140Cap in Rag2−/−γc−/− mice resulted in normal primary tumor growth compared with the controls. Strikingly, p140Cap over-expression causes an 80% inhibition in the number of lung metastases. p140Cap over-expressing cells display a 50% reduction in directional cell migration, an increased number and size of focal adhesions, and a strong impairment in the ability to invade in a 3D matrix. p140Cap over-expression affects EGFR signaling and tyrosine phosphorylation of cortactin in response to EGF stimulation. Intriguingly, p140Cap associates with cortactin via interaction with its second proline-rich domain to the cortactin SH3 domain. The phosphomimetic cortactin tyrosine 421 mutant rescues migration and invasive properties in p140Cap over-expressing cells. Taken together, these data demonstrate that p140Cap suppresses the invasive properties of highly metastatic breast carcinoma cells by inhibiting cortactin-dependent cell motility.

p130Cas and p140Cap as the Bad and Good Guys in Breast Cancer Cell Progression to an Invasive Phenotype

Breast cancer is an aggressive malignancy affecting a large woman population. Even though important progress have been made in providing new therapies to treat this neoplasia, our knowledge on the mechanisms underlying the transformation of breast epithelial cells in tumor cells is still superficial. The neoplastic phenotype results from the alteration of multiple cellular signaling mechanisms controlling proliferation, survival and invasiveness. Moreover, the prognosis of breast cancer patients is tightly correlated with the degree of spread beyond the primary tumor. However the mechanisms by which epithelial tumor cells escape from the primary tumor and colonize a distant site are not entirely understood. In this chapter we will discuss recent data on the relevance of p130Cas and p140Cap adaptor molecules in breast cancer signalling related to the acquirement on invasive properties. Due to the presence of adaptor modules, these proteins create signalling platforms proximal to plasma membrane cell surface receptors, such as integrins and growth factor receptors. p130Cas and p140Cap exert opposite regulation on cell signalling. Indeed p130Cas has been shown to increase survival, proliferation and migration of normal and transformed cells either in response to cell matrix adhesion or to hormones and growth factors. Moreover, p130Cas has been recently linked to resistance to breast cancer treatments, revealing its potential use as a novel therapeutic target. Instead, p140Cap behaves as a potent negative regulator of signalling pathways leading to cancer cell proliferation and migration. In this chapter, we will discuss the increasing evidence that highlight the importance of these adaptor proteins in breast cancer. It is well established that to migrate and to invade a cell needs to detach from its neighbors, i.e. adjacent cells in an epithelium, to extend lamellipodia and filopodia from the leading edge and to create new dynamic adhesions, which form and rapidly disassemble at the base of protrusions (Mitra et al., 2005; Ridley et al., 2003). Cell invasion also requires the release or activation of proteases that degrade the extracellular matrix (ECM) and allows cells to sort out from the basal lamina invading surrounding tissues (Eliceiri et al., 2002). Under physiological conditions cell motility and invasion are tightly controlled by a complex interplay among cell-cell, cell matrix and growth factors receptors resulting in the maintenance of the architectural integrity of human tissues. This subtle regulation is lost in