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Wide-angle seismic sea-land acquisition a A Ger asi 12 I G erra 2 RL Festa 2 R de Franco 3 GC Istituto per la Dinamica dei processi ambientali Gruppo Nazionale di Geofisica della Terra Solida 34 Introduction The main objective of the CHIANTI-1 cruise (Calabrian Arc Hazards in IoniAN and TyrrhenIan Seas is to collect several transects of deep penetrating wide angle seismic (WAS) data, together with sediment profiler and multi-beam bathymetry data, across the Ionian and Tyrrhenian seas to determine the deep crustal structure and plate geometry of the whole subduction system from the frontal wedge to the arc and back arc The goal is A. Gervasi 1, 2 , I. Guerra 2 , R.L. Festa 2 , R. de Franco 3 , G. C B. M. Ligi 5 , I. 1 Istituto Nazionale di Geofisica e Vulcanologia, INGV-CNT, Rome, Italy; 2 Dipartimento di Biologia, Ecologia e Scien Italy; 4 Consejo Superior de Investigaciones Científicas - Institut de Ciències del Mar (CSIC-ICM), Barcellona, Spai the whole subduction system, from the frontal wedge to the arc and back -arc. The goal is to study the processes that operated during the subduction of the Ionian slab of oceanic crust under Calabria, which lead to the development of the Aeolian volcanic arc, and the subsequent opening of the Tyrrhenian basin, and are responsible of the geological hazards that threaten the region. In addition, the data acquired will allow us to improve the knowledge on the interrelationships between tectonics and magmatism to define the most significant geological hazards, including large earthquakes, tsunamis, submarine landslides, and volcanic eruptions. The data were collected using a temporary network deployed for few days (from 21 to 31 July, 2015) on the sea floor, with a series of Ocean Bottom Seismometers and Hydrophones (OBS/OBH). The experiment also included the on land recording with permanent and temporary seismic stations managed and deployed by Calabria University (UniCal). The temporary seismic stations were located along the transect Francavilla Angitola – Montepaone The project will benefit from data observed at the stations of the a) b) c) Angitola Montepaone. The project will benefit from data observed at the stations of the Italian National Seismic Network of INGV. The source of energy to acquire the data was an array of airguns with a total capacity of ~4750 c.i. The explored wide-angle seismic (WAS) transects were located both in Ionian and Tyrrhenian seas. During the cruise were followed all necessary measures to minimize underwater acoustic impact on marine life. Measures include continuous monitoring of the research activities by a team of three Marine Mammal Observers (MMOs) which used both visual and Passive Acoustic Monitoring (PAM) systems. Here we present the preliminary results (pre-processing) of the data recorded by the on- land temporary stations. The sea-land data will be later processed and integrated with OBS/H-WAS data and interpreted together with multichannel data, in order to construct models of the tectonic features and the seismic velocity structures of the crust and upper mantle. Float of airgun sub-array after deployment Airgun configuration of the CHIANTI - 1 seismic source. The size of the squares in the blue grid is 1x1 m. Vessel Sarmiento de Gamboa (CSIC) MCS data and WARR Shooting. Multi-channel reflection (MCS) and wide-angle reflection/refraction seismic data were acquired MCS data were acquired in common shot gather from 3450 m streamer (276 ch), shot spacing WARR data were acquired in common receiver gather from OBH, OBS, on-land stations; 90 s s Data recorded on land Starting from July 21 st , three temporary, continuously recording seismic stations were installed WAS2 profiles. All of them were equipped with Guralp CMG40T broadband sensors and data- UMTS/GPRS to the recording center at the UniCal Campus, while the last two recorded data on l points resulted in about 10 km. The westernmost station UC01 at Francavilla Angitola is still op July 31 st . In the panels in the first row below, record sections (Z components) of temporary UniCal station UC05 UC03 UC01 WAS1 normal and reduced times, together the bathymetry . Their interpretation is underway . In the su permanent INGV stations CET2 (fan arrangement), JOPP and PLAC, where high quality data ha more possible permanent peri-tyrrhenian stations has been scheduled. WAS2 CET2 JOPP Record section of OBS35 along WAS3 (vertical component) Examples of OBS records Record section of OBS19 c CHIANTI-1 project: nd preliminary results Caielli 3 A Corsi 3 V Sallares 4 CR Ranero 4 N Zitellini 5 4° CONVEGNO TRIESTE 17-19 Novembre 2015 Dipartimento di Biologia, Ecologia e Scienze della Terra Caielli 3 , A. Corsi 3 , V . Sallares 4 , C.R. Ranero 4 , N. Zitellini 5 , Grevemeyer 6 nze della Terra, Arcavacata, Italy; 3 IDPA Institute for the Dynamics of Environmental Processes (CNR), Milan, n; 5 ISMAR - Istituto Scienze Marine (CNR), Bologna, Italy 6 IFM-GEOMAR, Kiel, Germany. Acquisition layout a) b) b) Bathymetric map of the study area with the WAS transects, labeled WAS1 to WAS4 (red lines). Yellow circles labeled OBS01 to OBS49 indicate the OBS location along WAS1, WAS2 and WAS3 profiles. Red circles labeled OBS05 to OBS67 indicate OBH location along the WAS4 profile. Seismic stations operating in Calabria and adiacent regions. Red triangles: INGV/CNT stations; green: UniCal permanent stations; blue: UniCal temporary stations (eastward from the West: UC01, UC03 and UC05). Coloured relief map of profiles WAS1 and WAS2 acquired during Leg 2. c) b) Signature of thr source wavelet used during the CHIANTI-1 wide-angle seismic cruise - e Ocean Bottom Hydrophone (OBH) Ocean Bottom Seismometer (OBS) shooting twice the same lines using different devices, geometry and acquisition parameters. 50 m, fold 35, source 9 G-II airguns 3040 inch 3 hoting interval, ~220 m shot spacing, source two arrays of 9 G-II airguns, 4750 inch 3 . UC01 seismic station at Francavilla A. (VV). d by UniCal on the transect joining the WAS1 and -loggers Reftek-72A. The first one was linked via ocal HD. The distance between adjacent recording perating while the other ones were deactivated on ns on the on-land transect are represented both in UC05 UC03 UC01 WAS2 ccessive one, we report the record sections of the ave been recorded. The utilization of data from as PLAC along WAS2 (vertical component) Record section of OBS17 along WAS1 (vertical component)
