The RSNI Seismic Network

Laboratory of seismology, DISTAV - University of Genoa (Italy)

www.distav.unige.it/rsni

RSNI STAFFRSNI STAFF : Spallarossa D., Barani S., De Ferrari R., Ferretti G., Pasta M., Pavan M., Scafidi D., Turino C. (E-mail: daniele@dipteris.unige.it)

INTERREG project preparation meeting

July 10-11, 2014 Trieste, Italy

RSNI seismic stations

RSNIRegional Sesismic Network

of North Western Italy

Team: 5 person

Stations: realtime trasmission (Nanometric Taurus)

Stations: BB and Episensor (Nanometric Trillium 40 s)

Seismic stations connected in REAL-TIME to the RSNI datacenter (Genoa)

RT data exchange: SeedLink and Nanometric softwares

The main aims of the RSNI Data Processing Centre (DPC) are:

• Real-time monitoring of the seismicity of the South-Western Alps and Northern Apennines. (location, magnitude estimate, shake maps)

• Daily manual revision of the detected seismic events.

• Dissemination of seismic data (location and ground motion parameters, waveforms) by WEB interface, E-Mail and SMS.

RSNI Data Processing Center

Event detection: Nanometric software

Event detection:Ml < 0.5

Automatic Event Location:RSNI-Picker

RSNI-Picker Automatic picking and location procedure

• The RSNI-Picker is represented by an iterative procedure consisting of different stages which calculate P- and S-arrival times and also earthquake location

• P- and S-wave arrival times are obtained by calculating the AIC function from filtered seismogram

• The AIC-based module is driven (i.e.: selecting the proper part of the signal) by the use of a-priori information derived from the characteristic of the signal (i.e.: envelope function) or from the results of the previous iteration (i.e earthquake location)

• RSNI-Picker produce consistent arrival times, quality class assignment to automatic readings, and remove gross errors and false picks. The performance of the picker has been tested using three different data set: NW Italy, California and New Zeland

RSNI dataset (Italy)Performances of the RSNI-Picker

• Picking hit-rate (e.g., the ratio between number of common automatic and manual readings and all available manual ones): 80% for P and 62% for S.

• The picker identified 82% of automatic readings with differences lower than 0.1 s and only 0.5 % of readings with differences greater than 0.5 s

• For S-phases the picker provided 42.0 % of readings with differences lower than 0.1s, 70% with differences lower than 0.2 s and 10 % with differences greater than 0.5 s,

Earthquake locations (RSNI database - Manual vs. Automatic picking)

Performances of the RSNI-Picker

SCEDC dataset (California)

Performances of the RSNI-Picker

GeoNet dataset (New Zealand)

Performances of the RSNI-Picker

Seismic tomography

Performances of the RSNI-Picker

The analysis of the differences between tomographic results, in terms of absolute P wave velocities (km s-1) obtained using the automatic pickings and the manual ones, shows that the 95 % of the differences are less than 0.5 km s-1. The same analysis in terms of VP/VS ratio shows that the 95 % of the differences are less than 0.08.Moreover, the greater differences are confined at the border of the model, while only smaller differences are confined inside the study area of the Trentino region.

CONCLUSIONS:- Our automatic picking procedure performs well with this very heterogeneous dataset.- The number and the quality of automatic P and S onsets are not far from the manual ones.- The small differences observed among tomographic results permit to demonstrate that our automatic picking engine can be used for reprocessing large amount of seismic recordings also with the aim of performing a local tomographic study.

Items for draft proposal

Calibration of the RSNI picker (Turino et al., 2010 – Spallarossa et al., submitted to SRL) for its application in Central Europe

Comparison among performances of automatic pickers and automatic location procedures

Producing shakemaps in Central Europe: calibration of relationships between Peak Ground Acceleration, Peak Ground Velocity and Modified Mercalli Intensity for producing Instrumental Intensity map by Shakemap© code

Calibration of an Ml scale in Central Europe