29m 44 49 "Pozzolane Nere" "Pozzolane Rosse" Paleosoil Lava K % U Th 0 200 Susz Rshallow 0.05 5000 Ohm m Rdeep 0.05 5000 Ohm m Cmax DIP 70 120 WF Near 200 1300 us Ftot DIP Cmax FAC 70 120 Devi FAC ° Devi DIP ° Ftot FAC 25 35 MU Fhor DIP Drift DIP 0 360 ° ° Drift FAC 0 360 Vp 5000 0 4 0 4 0 pl north normalised to 0° 0° 180° 90° 270° Structures 0° 0° 180° 90° 270° 30.0 32.0 34.0 36.0 38.0 40.0 42.0 44.0 46.0 48.0 GR master (SGR) 0 0 0 100 20 1000 0 m 21 44 67 82 93 99 124 141 173 "Pozzolanelle" (366+/-4Ka*) "Pozzolane Nere" (407+/-4Ka*) "Pozzolane Rosse" (457+/-4Ka*) "Vallerano Lava" (460+/-4Ka*) "Tufi Terrosi" (488+/-2Ka*) "Tufo del Palatino" (528+/-1Ka*) "Tufo Pisolitico di Trigoria II" (561+/-1Ka*) "Tufo Pisolitico di Trigoria I" (561+/-1Ka*) Paleosoil Soil-anthropogenic fill Paleosoil Pedogenized layer Pedogenized layer Pedogenized layer Pedogenized layer Paleosoil "Tufo di Bagni Albule" (526+/-1Ka*) Lava 189 350 344 Sand Gravel Sand Clay 40 26 60 80 100 120 140 160 180 200 220 240 260 GR_Master_hole1 0 0 10 1000 gAPI K % U 0 100 ppm Th 0 200 ppm GRS 0 1000 Gamma 0 1000 0 1000 GR.MS 0 1000 gAPI GR.DIP 0 4 0 4 0 360 0 360 Susz Rshallow 0.05 5000 Ohm m Rdeep 0.05 5000 Ohm m Cmax DIP Cmax FAC 70 120 WF Near 200 1300 0 1E SI 1000 us Ftot DIP 70 120 Devi FAC Devi DIP Ftot FAC 25 35 MU Fhor DIP Drift DIP Drift FAC Vp 5000 0 Pl north normalised to 0° 0° 180° 90° 270° down-hole logging down-hole logging Hydrofrac tests samples for laboratory analysis g.l. (120m a.s.l.) Volcanic units Clay 76mm SEISMOMETER Sand 123mm 152mm 178mm 96mm Casing 0-200m Cemented 200-350m BOP O 0 50 100 150 200 250 300 350 *After: Karner, D.B., Marra, F. & Renne, P. (2001) - Journ. of Volc. and Geoth. Res., 107. 2.5 3 3.5 4 4.5 5 5.5 6 6.5 180 200 220 240 260 280 300 320 Depth (m) Magnetic susceptibility (10-6 SI) 12.8° 12.9° 41.8° 41.9° 0 5 10 km Velletri e Genzano 41.7° 12.7° 12.6 ° Permanent Stations INGV Mobile Stations seismic sequence Jan06 M=2.7 M=2.6 M=2.3 M=2.4 Albano L. Rocca-Priora Monte-Porzio-Catone 4 2 T13A-0493 mariucci@ingv.it Istituto Nazionale di Geofisica e Vulcanologia Via di Vigna Murata 605 00143 Roma ITALY *Seismology and Tectonophysics Department, rome (italy) # Geomagnetism, Aeronomy and environmental geophysics DEpartment, rome (Italy) -156 samples of Clay were collected to perform the magnetic susceptibility to be compared with log data (FIG. 20). -14 stratigraphyc samples of Clay were collected to perform the chronostratigraphic analysis. -2 samples of Clay will be analysed to measure Vp/Vs and mechanical properties. -8 samples were taken for different petrographyc analysis. -other samples will be analysed to measure the physical and mechanical properties of volcanic rocks. -some samples to determine clay minerals. -moreover we will analyse with electronic microscope some faults with striae recognized in the sedimentary units. First Results From the Scientific Drilling in the Colli Albani Volcanic Area M.Teresa Mariucci*, Simona Pierdominici*, Fabio Florindo # , Fabrizio Marra*, Paola Montone* For the first time in Italy, a borehole was drilled, SE of Rome in the Colli Albani volcanic district, for scientific purposes. The 350m borehole contributes to understand the structure and the dynamics of the shallow crust in the Quaternary volcanic complex now quiescent, characterizing the rock units and defining the present stress field and its evolution in recent times. The borehole will host a broad-band seismometer for good seismicity records in a very urbanized area. We present the on site activities and the preliminary results of borehole data analysis. The well is located in the most interesting area of the volcanic complex where: 1) most seismic swarms occur; 2) geodetic and satellite investigations determined an ongoing uplift; 3) gas (CO 2 and H 2 S) concentration in water is high; 4) local tectonics is peculiar; 5) stress data lack. Wireline drilling produced a complete stratigraphic record of the volcanic units down to the sedimentary basement. Down-hole logs were carried out such as: gamma-ray, resistivity, sonic, borehole televiewer, caliper and magnetic susceptibility. Due to the shallow depth the whole logs are compared with cores. The Gamma-Ray provides a clear characterization of volcanic units and the definition of the intervals that most contribute to radioactivity. Resistivity and Sonic logs give a major definition of the different units and their characters. Caliper log and BHTV supply data (breakouts, fractures and faults) from which we interpret the main tectonic features and the present-day stress. The blow-out occurred in the deeper sandy unit did not allow to perform the hydrofrac tests but allowed to sample deep fluids and gases for geochemical analysis that will contribute to better understand the complex fluid flow and its relationships with the magmatic chamber. A detailed magnetic susceptibility analysis is performed on shale samples. Moreover Biostratigraphic analysis are performed for a complete reconstruction of sedimentary sequence. Mechanical analyses are planned to understand the behavior of the volcanic rocks at high pressures and temperatures. Dynamic tests on Pliocene clays, joined with the sonic log and other laboratory measurements of Vp/Vs, will provide data on the real seismic behavior of these units, useful for understanding the local seismic response. INTRODUCTION DRILLING and on site activities ACKNOWLEDGMENTS We performed a continuous coring wireline drilling with diamond bit (FIG. 2) up to 350m depth with a recovery of about 100%. The cores, 3m long (FIG. 3), were cut in pieces of 1 meter and accomotaded inside wood boxes (64 boxes). The drilling, started at the end of April and ended the beginning June 2006, was performed by an italian company (SO.RI.GE. s.r.l.) using the Casagrande C8 drilling machine (FIG. 1). Hydraulic Fracturing Test. To obtain the information on stress field around the Colli Albani area, some loggings and tests were planned. One of our aims was to compute the values of stress principal axes by means of some Hydraulic Fracturing tests. We planned three HF tests between 320 and 350 m, for each test three cycles would have been performed. Figure 6 shows the probe for HF, characterized by two pakers (black parts) and by a central part where the fluid comes into the test chamber and is pressurized till a failure occurs. The Figure 7 and 8 show the tool cables and control unit (SialTec Engineering s.r.l.). Unfortunately, during the phase of probe positioning, a blow-out occurred (FIG. 9, 10, 11), destroying the deepest part of borehole (300-350m, 76mm φ ) and the tests were cancelled because the HF tool for a larger hole (96mm φ) was not available. Geochemical analysis. During the blow-out gas and fluid samples were taken and analysed both in situ (FIG. 12- radon analysis and FIG. 13- carbonate titration) and in laboratory. Logging analysis. We have performed some downhole logging along the well to investigate the physical properties of the rocks. Figure 16 shows the stratigraphy from core analysis in the left side and the corresponding logging data on the right. The Gamma Ray is located in the first column, and in the following columns we have quoted the K, U, Th concentrations. In yellow we have highlighted some significant details. Just for a small part of the well we could perform the other logs, shown on the right (caliper, resistivity, borehole televiewer image, sonic and susceptibility). Detail of log data. The detail of logs from 29m to 49m depth in particular shows some fractures from the analysis of borehole televiewer data (FIG. 17). We have recognized 213 fractures and 143 on cores. We are analysing these fractures with Daisy3 software (by F. Salvini, http://host.uniroma3.it/progetti/fralab/). Figure 18 shows the poles of 105 fracture planes with dip greater than 45°. They can be compared with the focal mechanisms of main events of a seismic sequence that occurred in the Colli Albani area last January (FIG. 19). Log measurements. Some downhole loggings were performed along the well (by the ICDP Operational Support Group) to measure the properties of volcanic rocks in situ. The following loggings were done: Gamma Ray, Four-arm Dipmeter (FIG. 14), Borehole Televiewer, Sonic (FIG. 15), Magnetic and Electric. See also Figures 16 and 17 for results. 1 LABORATOry ANALYSIS DOWNhole logs As this area is characterized by a high gas concentration in water (mainly CO 2 and H 2 S), a blow-out preventer was installed and combustible gases and H 2 S were monitored continuously at well head for safety reasons (FIG. 4). Sketch of drilling (FIG. 5) with main lithological units, borehole diameters, planned analysis, casing and seismometer depth (200m, installation next January). 2 3 3 4 5 5 6 6 9 9 10 10 11 11 13 13 12 12 7 7 8 8 1 14 14 This work was funded by: -the Italian "Dipartimento della Protezione Civile" in the frame of the 2004-2006 Agreement with "Istituto Nazionale di Geofisica e Vulcanologia- INGV", Project V3.1; -the Italian Ministry for University and Research in the frame of FIRB Project "Research and Development of New Technologies for Protection and Defense of Territory from Natural Risks", Working Package C3; -INGV Department "National Earthquake Center", Rome; -INGV Department "Seismology and Tectonophysics", Rome. We thank ICDP Operational Support Group (GFZ- Potsdam, Germany). Detail of logs 18 18 For information about seismological studies within INGV-DPC V3.1 Project "Colli Albani" We invite you to look at poster S53A-1318 "Crustal structure of the Alban Hills volcano inferred by RF studies" by Bianchi et al. on Friday 15 h13:40 at Moscone West level 2 detail in FIG. 17 43-48m A 78-83m B B C D E A 262-268m D 168-173m 138-143m C 20 19 19 15 15 16 16 17 17 Magnetic Susceptibility. Preliminary results of measurements on cores in the sedimentary units (FIG. 20). Note these values are much lower than those in the volcanic cover, from down hole log ( FIG. 16, above), and seem to decrease with depth. CA1 borehole 20 a a b b January 2006 seismic sequence (courtesy of P. De Gori, INGV)