Pattern of seismicity in the Lucanian Apennines and foredeep (Southern Italy) from recording by SAPTEX temporary array

The deployment of a temporary seismic network in Southern Italy during 2001-2004 (the SAPTEX array, Southern APennine Tomography EXperiment) allowed us to relocate the hypocenters of Southern Apennines earthquakes with low uncertainty among the location parameters. The best array distribution of the SAPTEX network for the analysis of seismicity in the Lucanian Apennines and foredeep was reached in the first two years of recording. The SAPTEX data were merged with those of the Italian National Seismic Network (RSNC) operated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). For the hypocenters computation of events in the upper Agri Valley we also included P- and S- waves arrivals from the local Eni-Agip network. The seismicity for the Lucanian Apennines and foredeep in the analyzed period has magnitudes ranging from 2.0 to 4.1. A major finding is the identification of two different crustal domains: the westernmost characterizing the chain, mostly with shallow earthquakes (within about 20 km of depth), and the easternmost one belonging to the outer margin of the chain and to the foredeep, with deeper seismicity (mostly between 20-40 km of depth). Thirty fault-plane solutions were computed and used for stress inversion; most of them are related to earthquakes within the chain sector and indicate a generalized NE-SW extension. Moreover, the dense network allowed us to improve the location of events relative to two low magnitude sequences which occurred in the study period

Surface evidence of active tectonics along the Pergola-Melandro

The Pergola-Melandro basin (southern Apennines) is characterized by a below-average release of seismic energy within a wider earthquake-prone region. In fact, it is placed between the maximum intensity areas of two of the most destructive earthquakes reported in the Italian seismic catalogue: theM≥7.0 Agri Valley earthquake in 1857 and the Ms = 6.9 Irpinia earthquake in 1980. In thiswork, we present geomorphologic analysis, electrical resistivity surveys and field data, including paleoseismologic evidence, that provided the first direct constraints on the presence of a∼20 kmlong, seismogenic fault at the western border of the Pergola-Melandro basin. We also obtained geological information on the recent deformation history of the Pergola-Melandro fault that indicates the occurrence of at least four surface faulting earthquakes since Late Pleistocene age. The empirical relationships linking fault length and magnitude would assign to the Pergola-Melandro fault an event of M≥6.5. These new data have important implication on the seismic hazard assessment of this sector of the Apennines, that also includes large cities such as Potenza, about 20 km far from the recognized Pergola-Melandro fault, and highlight the relevance of the geological approach in areas where the seismological records are poor. Finally, we discuss the Pergola-Melandro fault within the regional seismotectonic context. In particular, this fault belongs to the system of normal faults with an apenninic orientation, both NE and SW dipping, accommodating the NE-crustal extension taking place in the area. Nearby faults, similarly oriented but with opposite dip, may coexist whether linked by secondary faults that act as slip transfer structures. This complex system of active faults would be more realistic than a narrow band of faults running along the belt axis with an homogenous geometry, and moreover, it is more consistent with the high extension rate measured by historical earthquakes and geodetic data

role of the lower hybrid spectrum in the current drive modeling for demo scenarios

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Overview of progress in European medium sized tokamaks towards an integrated plasma-edge/wall solution

Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n  =  2 RMP maintaining good confinement HH(98,y2)≈0.95. Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes.Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n = 2 RMP maintaining good confinement H-H(98,H-y2) approximate to 0.95. Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes.Peer reviewe

Current drive at plasma densities required for thermonuclear reactors

Progress in thermonuclear fusion energy research based on deuterium plasmas magnetically confined in toroidal tokamak devices requires the development of efficient current drive methods. Previous experiments have shown that plasma current can be driven effectively by externally launched radio frequency power coupled to lower hybrid plasma waves. However, at the high plasma densities required for fusion power plants, the coupled radio frequency power does not penetrate into the plasma core, possibly because of strong wave interactions with the plasma edge. Here we show experiments performed on FTU (Frascati Tokamak Upgrade) based on theoretical predictions that nonlinear interactions diminish when the peripheral plasma electron temperature is high, allowing significant wave penetration at high density. The results show that the coupled radio frequency power can penetrate into high-density plasmas due to weaker plasma edge effects, thus extending the effective range of lower hybrid current drive towards the domain relevant for fusion reactors

Corrigendum: Current drive at plasma densities required for thermonuclear reactors

Nature Communications 1: Article number: 55 (2010); Published: 10 August 2010; Updated:19 September 2013. In Fig. 3 of this Article, the colours of the blue and green curves were accidentally interchanged while the manuscript was being revised. In addition, the x axis labels on Fig. 4 should have read 'Frequency (MHz)'