Improving CTBTO monitoring capabilities:the Italian proposal for a CNF

Damiano Pesaresi1, Nikolaus Horn2

1) OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale), ITALY, dpesaresi@inogs.it2) ZAMG/CTBTO NDC, AUSTRIA, Nikolaus.Horn@zamg.ac.at

ABSTRACT. The Centro di Ricerche Sismologiche (CRS, Seismological Research Center) in Udine (Italy) of the OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale), the Italian National Institute for Oceanography and Experimental Geophysics, after the M=6.4 earthquake occurred in 1976 in the Friuli-Venezia Giulia region, started to operate the Northeastern Italy Seismic Network: it currently consists of 18 very sensitive broad band and 20 simpler short period seismic stations, all telemetered to and acquired in real time at the OGS-CRS data center. OGS is formally part of the Central and Eastern European Earthquake Research Network CE3RN (http://www.CE3RN.eu/; Bragato et al., 2014). Real time data exchange agreements in place with CE3RN and other Italian and Swiss seismological institutes lead to a total number of about 100 seismic stations acquired in real time by the CRS, which makes the OGS the reference institute for seismic monitoring of Northeastern Italy (Bragato et al., 2011).To further support CTBTO activities (Pesaresi and Horn, 2004), OGS proposes with the support of the Italian CTBTO National Authority one of its stations of the Northeast Italy Seismic Network as a Cooperating National Facility (CNF) to the CTBTO. A description of the Cludinico (CLUD) station proposed as CNF, together with results of CTBTO monitoring improvements simulations will be here illustrated.

FINES PS17 CERT PS Finland Lahti North America and Western Europe 61.4436 26.0771HFS AS101 CERT AS Sweden Hagfors North America and Western Europe 60.1342 13.6956NOA PS27 CERT PS Norway Hamar North America and Western Europe 60.8238 10.8324EKA AS104 CERT AS UK Eskdalemuir North America and Western Europe 55.3339 -3.1923OBN AS084 CERT AS Russia Obninsk Eastern Europe 55.1200 36.5700AKASG PS45 CERT PS Ukraine Malin Eastern Europe 50.7010 29.2242VRAC AS026 CERT AS Czech Republic Vranov Eastern Europe 49.3083 16.5935GERES PS19 CERT PS Germany Freyung North America and Western Europe 48.8451 13.7016DAVOX AS102 CERT AS Switzerland Davos North America and Western Europe 46.7806 9.8798MLR AS081 CERT AS Romania Muntele Rosu Eastern Europe 45.4917 25.9437ESDC PS40 CERT PS Spain Sonseca North America and Western Europe 39.6744 -3.963

BRTR PS43 CERT PS Turkey Belbashi North America and Western Europe 39.7250 33.6390VAE AS050 CERT AS Italy Enna, Sicily North America and Western Europe 37.4690 14.3533KEST PS42 CERT PS Tunisia Thala Africa 35.7317 9.3460MDT AS066 CERT AS Morocco Midelt Africa 32.8140 -4.6070IDI AS036 CERT AS Greece Anogia, Crete North America and Western Europe 35.2880 24.8900CLUD CNF AS Italy Cludinico North America and Western Europe 46.4569 12.8814Station code Trety number Status Technology State Location Region Latitude Longitude

Map (left) and list (up) of CTBTO seismic stations in the Euro-Mediterranean region.In red the proposed Italian CNF Cludinico (CLUD).

OGS CLUD seismic

station. Anti-clockwise: the satellite data link antenna, the entrance of the mining tunnel, sensors installation (Nanometrics Trillium 120 seismometer left and accelerometer right), Power Spectral Density plot close to Low Noise Model (green line). The Data logger is a 26 bit Quanterra Q330 High Resolution. The installed instrumentation is “substantially meeting” CTBTO specifications.

REFERENCESBragato, P.L., Costa, G., Gallo, A., Gosar, A., Horn, N., Lenhardt, W., Mucciarelli, M., Pesaresi, D., Steiner, R., Suhadolc, P., Tiberi, L., Živčić, M., and Zoppé, G.: The Central and Eastern European Earthquake Research Network - CE3RN, EGU General Assembly 2014, Vienna, Austria, 27 April – 2 May 2014, B584, EGU2014-13911, 2014.Bragato, P.L., Di Bartolomeo, P., Pesaresi, D., Plasencia Linares, M.P., and Saraò, A.: Acquiring, archiving, analyzing and exchanging seismic data in real time at the Seismological Research Center of the OGS in Italy, Annals of Geophysics, 54(1), 67-75, doi:10.4401/ag-4958, 2011.Pavlis, G. L., Vernon, F. L., Harvey, D., and Quinlan, D.: The generalized earthquake location (GENLOC) package: A modern earthquake location library, Computers in Geosciences, 30, 1079–1091, 2004.Pesaresi, D. and Horn, N.: Data integration from the scientific community and CTBTO: the Italian NDC experience with Antelope, Seism. Res. Letters, 75, 379-384, 2004.

T4.1-P31

ANALISYS METHODOLOGY

We downloaded from the CTBTO IDC SEL3 and REB arrivals from all the IMS network for about 1 year of data, from 06/07/2014 to 30/05/2015. We added to these 2 datasets arrivals from CLUD stations for the same time period: the automatic ones to SEL3 dataset, the manually reviewed ones to REB dataset. For both datasets we computed a very basic but very fast automatic grid search location using the standard Antelope routines (Pesaresi and Horn, 2004) and then refining the location with the generic Gauss-Newton algorithm of the genloc family of location programs (Pavlis et al., 2004). Resulting datasets contain more than 300.000 phases of data. For both datasets we computed azimuth gap and error ellipse area. We then evaluated results in the Europe/Middle East area box with 25° < latitude < 70° and -9° < longitude < 63°.

RESULTS

The full worldwide REB dataset contains 15.618 events: CLUD stations contributed to 97% of them, 15.143. Azimuth gap in the Europe/Middle East area basically remains unchanged to an average of 107°.Error ellipse area to the contrary clearly improved with the usage of CLUD station: from an average of 5.94 km2 down to 4.72 km2, with a decrease of 21%.

The full worldwide SEL3 dataset contains 9.275 events: CLUD stations contributed to 96% of them, 8.863. Azimuth gap in the Europe/Middle East area basically remains unchanged to an average of 120°.Error ellipse area to the contrary clearly improved with the usage of CLUD station: from an average of 8.82 km2 down to 6.53 km2, with a decrease of 26%.

CONCLUSIONS

Even with this very simple analysis, it is evident the improvement of the CTBTO location capabilities in the Europe/Middle East area.More extensive and deep analysis is though needed, perhaps using CTBTO location algorithms and station specific corrections.