Scientific drilling in a central italian volcanic district

This article introduces the 350m scientific borehole performed in the Colli Albani area. It describes the technical features of the drilling and the on-site measurements, and summarizes the main ongoing researches on data and samples from the borehole

Comparison between active stress field and tectonic structures in Northern Italy, Lombardy Region

The aim of this work is to understand the complex pattern of active stress field orientations revealed by borehole breakout analysis with respect to the tectonic structures in a wide region of Northern Italy. The area is located in the central-western part of the Po Plain between the south verging Southern Alps structures and the north verging buried folds and thrusts of the Monferrato and Emilia arcs. Little information concerning the active stress field is available because of the low seismicity level and the thick layer of sediments that covers the entire zone. A detailed borehole breakout analysis has been performed in 36 wells with depths ranging from 2.2 to 7.3 km, whose data have been supplied by Eni. Breakout analysis determined the minimum and maximum horizontal stress directions (Shmin and SHmax). The results show a very complex pattern, pointing out that the stress field is not uniform. In this area the regional stress field seems not «strong» enough, compared to the local one, so most of the wells detect only the local field. This work contributes to clarify the various Shmin orientations observed in this area, pointing out at wide scale, a general compression in NNE-SSW direction in this complex region

Active stress field in central Italy: a revision of deep well data in the Umbria region

In this area the active stress from borehole breakout analysis shows a prevalent NE-SW extension, perpendicular to the main tectonic structures, in agreement with stress inferred from earthquake focal mechanisms and with the strain velocity field. A detailed analysis of active stress data allows to infer the influence of active structures on the local stress field orientations. San Donato 1 well shows a minimum horizontal stress orientation N55±22°, in agreement with the regional trend and with the local one influenced by its vicinity to the Alto Tiberina Fault. Whereas Monte Civitello 1 well shows a quite different orientation, N12±29°, due to its different location, more to the east, and to the structures that it crosses. Although the angular difference between the two directions is within the error, to estimate the regional active stress field many borehole data should be analysed or smoothing maps should be evaluated. In fact, each borehole dataset could be influenced by local stress conditions that in some case can be different from the regional trend. The two breakout orientations perfectly depict the regional extension along the axis of the Apennines and also the minimum horizontal stress rotation moving eastward to the area where compression is predominant

A proposal for compiling quantitative hydrogeological maps

An innovative approach to hydrogeological mapping based on quantitative analysis is shown in this paper. It gives some cartographical solutions for an immediate evaluation of the groundwater resources and their spatial distribution. All relevant aquifers, springs and their regime, geological and structural setting and their hydraulic role should be shown in several understandable and clear hydrogeological maps where all hydrogeological information is reported in detail in the “Hydrogeological experimental Map” composed by a. “Hydrogeological Complexes and Natural Springs Map”, b. “Surface Hydrology Map”, c. “Conceptual Hydrogeological Model” and d. “Hydrogeological sections”. The cartographical solutions adopted for representing all these documents are proposed in this paper. Some graphical solutions have been proposed for improving the Italian official guidelines of hydrogeological mapping at scale 1:50.000, explain the legends symbols and illustrate the structure of a hydrogeological GIS database. An application of this approach has been carried out in north-western sector of Sibillini Mts. (Marche, Italy)

The MOLE Drilling Project: Laboratory at Depth on an Active Fault in Central Italy

Several fundamental questions concerning: i) the geophysical and geochemical processes controlling normal faulting and earthquake ruptures during moderate-to-large seismic events and ii) the low angle normal fault paradox, still need to be fully answered. In this work we aim to present an example of low angle normal fault (Alto Tiberina Fault) located in the Northern Apennines (Italy) showing conclusive evidence of its seismic activity. This fault is a likely target of an international project: the MOLE (Multidisciplinary Observatory and Laboratory of Experiments) Drilling project. Indeed, under the auspices of the International Continental Scientific Drilling Program a workshop is being organized in Italy next spring 2008, to promote the creation of an international multidisciplinary team of scientists, to discuss the project in detail and also to prepare a full proposal for ICDP. This project wants to investigate the inner structure of normal faults in Central Italy to get physical constraints on the processes controlling faulting and earthquake mechanics. The Umbria-Marche sector of Northern Apennines offers a unique opportunity to reach a complex system of normal faults among which we selected two possible targets. 1) The active Colfiorito fault dipping about 45° toward SW which Tiberina low angle normal fault dipping 15°-25° towards ENE, which moves through a combination of aseismic creep and repeating microearthquakes. Drilling the Colfiorito active fault at a depth of about 2-3 km allows targeting the high coseismic slip patch of the 1997 earthquake M=6 seismogenic structure. Drilling the Alto Tiberina Fault at a depth of nearly 5-6 km will target a micro seismicity source. We aim to collect new original data through borehole logging and sampling and to set up a permanent observatory at depth for a multidisciplinary monitoring to characterize these active normal fault zones. This will allow to understand how such faults behave and to create more realistic models of: earthquake nucleation, seismicity pattern, stress interactions and earthquake triggering at local and regional scale. Both drilling targets present relevant technical issues that should be discussed from different points of view before selecting the starting drilling site

Understanding volcanic facies in the subsurface : a combined core, wireline logging and image log data set from the PTA2 and KMA1 boreholes, Big Island, Hawaii

Data availability. A digital archive of core photos and detailed core run depth log information is available at https://www.higp.hawaii.edu/hggrc/projects/humuula-groundwater-research-project/(HGGRS, 2019). The down-hole data are published with a digital object identifier via GFZ Data Services (Kück, 2019). Acknowledgements. This project was made possible by the collaborative outlook of the main partners (VBPR and DougalEARTH, GFZ, and the University of Hawai‘i) and the extensive background work undertaken by the researchers at the Hawai‘i Groundwater and Geothermal Resources Center (University of Hawai‘i) and from the HGRP project. Jehanne Paris is thanked for helping organize the logging operations and helping in the field. Martin Töpfer and Marco Groh (Operational Support Group, OSG, of ICDP, GFZ) are thanked for ensuring the smooth running of the logging operations. Dougal Jerram and Sverre Planke are also supported by the Research Council of Norway, through its Centres of Excellence funding scheme, project 223272 at CEED, University of Oslo. We would like to thank Breno Waichel and John Shervais for constructive reviews and the editorial team at Scientific Drilling for their prompt handling and meticulous guidance through the various stages from submission to publication.Peer reviewedPublisher PD

Surface evidence of active tectonics along the Pergola-Melandro fault: a critical

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: the M ≥ 7.0 Agri Valley earthquake in 1857 and the Ma = 6.9 Irpinia earthquake in 1980. In this work, 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 km long, 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, that accommodate 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 to consider a narrow band of faults, running along the belt axis, with an homogenous geometry and, moreover, more consistent with the high extension rate measured by historical earthquakes and geodetic data

Comparison between active stress field and tectonic structures in Northern Italy, Lombardy Region

The aim of this work is to understand the complex pattern of active stress field orientations revealed by borehole breakout analysis with respect to the tectonic structures in a wide region of Northern Italy. The area is located in the central-western part of the Po Plain between the south verging Southern Alps structures and the north verging buried folds and thrusts of the Monferrato and Emilia arcs. Little information concerning the active stress field is available because of the low seismicity level and the thick layer of sediments that covers the entire zone. A detailed borehole breakout analysis has been performed in 36 wells with depths ranging from 2.2 to 7.3 km, whose data have been supplied by Eni. Breakout analysis determined the minimum and maximum horizontal stress directions (Shmin and SHmax). The results show a very complex pattern, pointing out that the stress field is not uniform. In this area the regional stress field seems not «strong» enough, compared to the local one, so most of the wells detect only the local field. This work contributes to clarify the various Shmin orientations observed in this area, pointing out at wide scale, a general compression in NNE-SSW direction in this complex region