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An Advanced Seismic Network in the Southern Apennines (Italy) for Seismicity Investigations and Experimentation with Earthquake Early Warning

Istituto Nazionale di Geofisica e Vulcanologia
Osservatorio Vesuviano
Via Diocleziano 328, 80124
Naples, Italy
iannaccone{at}ov.ingv.it
(G.I.)

View larger version (59K): [in this window] [in a new window]   Figure 1. (A): Map of recent instrumental seismicity with M > 2.5 recorded by the INGV in the period 1981-2002 in the region defined by the dashed rectangle. Dimensions of the circles are proportional to magnitude. The black lines represent the surface projection of the three fault segments that broke in the 23 November 1980 earthquake (M 6.9). B) Locations of the main historical earthquakes retrieved from the CFTI database within the region defined by the dashed rectangle. The box dimensions are proportional to magnitude. The best-constrained historical earthquakes are reported along with their dates of occurrence.

View larger version (104K): [in this window] [in a new window]   Figure 2. Station map of the Irpinia Seismic Network (ISNet). The squares represent the ISNet stations. Seismic stations with the sensors Guralp CMG-5T/Geotech S13-J are shown as squares without a black dot and those with the sensors Guralp CMG-5T/Nanometrics Trillium are shown as squares with a black dot. Also shown are the Network Control Center (RISSC) and the M 4.5 Gargano earthquake (star). The 12 stations for post-event applications, under construction, are shown as inverted triangles.

View larger version (64K): [in this window] [in a new window]   Figure 3. The ISNet communication system. The extended star topology and the subnets of the seismic network are visible. The squares represent the ISNet stations and the circles the Local Control Centres (LCC). The gray lines are the radio links between the stations and the LCCs, and the dashed lines are planned SDH carrier-class radio upgrades for early-warning applications. Also depicted is the radio ring between the LCCs and the two independent branches to the RISSC Control Centre in Naples that guarantees the necessary transmission redundancy. The triangles represent radio repeater points. The Network Control Centre (RISSC) and the main cities (black squares) in the region are marked. Squares with black dots correspond to stations equipped with the sensors Guralp CMG-5T and Nanometrics Trillium.

View larger version (38K): [in this window] [in a new window]   Figure 4. A schematic view of the data flow from the data-logger to the Control Centre in Naples and the three possible computational levels in the seismic network.

View larger version (83K): [in this window] [in a new window]   Figure 5. Network map ISNet Devices Manager (ISNM) database home Web page. The key shows the color scheme for site types and status and the communications links. On the top of the http page the links to the single-network-element Web pages are visible. On each site Web page, different site description data are available (status, location, photo, notes and files, SMS alerts, installation date, etc.) and the installed equipment is listed (connection type with nearest data analyzing system, data logger, sensors, and radio hardware).

View larger version (27K): [in this window] [in a new window]   Figure 6. Irpinia seismic sequence recorded at four ISNet stations (vertical components) arranged top to bottom as a function of the epicentral distance. The seismic moment (dyne-cm) is indicated above the corresponding event.

View larger version (42K): [in this window] [in a new window]   Figure 7. Irpinia sequence recorded at station VDS3 (plot of all horizontal component waveforms aligned at the first P-arrival time). Each trace is normalized at its own maximum amplitude.

View larger version (41K): [in this window] [in a new window]   Figure 8. Gargano earthquake: An example of vertical-accelerometer component data recorded at 13 stations. The records are all scaled to the same maximum amplitude.

View larger version (34K): [in this window] [in a new window]   Figure 9. North-south component displacement spectra for (A) the M0 = 1 x 1019 dyne-cm event of the Irpinia seismic sequence displayed in figure 7; and (B) the Gargano earthquake (Mw = 4.5) located about 150 km from the network center.