1. The Strong Motion Network: Synergy with the broadband seismic network Ioannis Kalogeras, Nikolaos Melis and Christos Evangelidis NATIONAL OBSERVATORY OF ATHENS INSTITUTE OF GEODYNAMICS P.O.BOX 20048, 11810 ATHENS

2. The geodynamic model in the broader area

3. NOAIG strong motion network till 2009 From 70s to 2009 Installations mainly in urban areas, 11-12bits instruments

4. NOAIG strong motion database updated till today for the stations and for records from the triggering mode instruments

5. Data available upon request

6. Local arrays have been implemented with the support of other organizations (municipalities, public organizations etc). Development of strong motion databases and dissemination of data. Establishment of a system for the telemetric maintenance of the network via the network of Hellenic State, aiming to enhance “traditional” accelerographic instruments equipped with serial interfaces. The NOAIG strong motion network till 2009

7. LAN 2Mbps NATIONAL OBSERVATORY OF ATHENS LAN Router PBX PSTN 2 – 34 Mbps PSTN/ ISDN BUILDING WITH SYZEFXIS CONNECTION VPN1, VPN2, …. Router ΣΥΖΕΥΞΙΣ SYZEFXIS NET REMOTE ADSL 2Mbps TOWN HALL KASTELLORIZO LAN Router 2 Mbps/SDSL 2 Mbps/ 512kbbs OTE KASTELLORIZO 1 2 3 4 Institute of Geodynamics & Syzefxis

8. New Hellenic Accelerographic Network Since 2009, NOAIG and ITSAK were financially supported by EPPO (i.e. national funds) in order to purchase modern accelerographs and to install them in the Hellenic territory aiming among others to: densify the national network homogenize the processing procedure disseminate the data as soon as possible after the occurrence of a strong earthquake Within this project, the 2 Institutions almost doubled the number of installed instruments reaching a total number of about 350 by 2012.

9. New Hellenic Accelerographic Network (II) The criteria of new installations are: Communication between the 2 Institution in order to avoid overlapping (establishment of a Committee for the development and operation of the National Accelerographic Network) Coverage of main cities (population > 5000) – larger cities with more than one instruments at different geological conditions – urban development Coverage of areas of high seismicity Coverage of large seismotectonic lines Coverage of areas according to hazard studies (ex. long term prediction) Coverage of sites of specific interest (large constructions, archaeological sites)

11. Example of a free-field installations

12. Example of in-building installations

13. Strong motion data archival, dissemination and storage The instruments in triggering mode produce data which are easily stored and disseminated, since they are small files. Our philosophy for strong motion records should be changed with the new-generation-instruments since they show the following: real-time transmission and in continuous mode they should processed not only as strong motion records but also as weak motion signals like the one from seismographs (miniseed format) 24bits 200-250s/s means about 100Mb per instrument per day or more than 10Tb per year for 300 instruments of that type at a national scale. The new generation strong motion instruments should be integrated into the seismic network

14. Development of a new web page for monitoring the accelerographic network

15. A record example of the new strong motion network: A SE Aegean Sea intermediate depth earthquake, April 1 st, 2011, 13:29, M6.0, h=69km

16. Strong motion records from distances between 40 and 750km and pga between 130 and 0.1mg (no missing triggers)

17. The Japan earthquake, March 11 2011, M9.0, R=9500km as recorded by an STS2 seismometer at NOAIG (ATH HHZ), and as calculated by de-convolution of the strong motion record from a CMG- 5TD accelerograph at the same site (NOAC HNZ)

18. Health monitoring of the continuous recording strong motion stations via the PQLX software The grey lines are the high and low noise level of Peterson’s model (1993). At high frequencies (<0.1s) the site noise is measured (artificial noise). Between 1 and 5s is the instrument noise and between 5 and 10s is the microseismic noise.

19. The red line represents the Low Noise Model and the grey area the 80% confidence intervals. The red line is the criterion for a station to be characterized as a good station for phase picking within the automatic location system. For method see Evangelidis & Melis (2012) Calculated noise model for Greece, based on the statistical mode of the PDF noise levels of all the 75 strong motion stations.

20. An example of a “quiet” and a “noisy” station

21. Strong Motion Stations that complements the BB HUSN network and used in the 24/7 analysis at NOAIG for hypocenter and magnitude determination. These strong motion stations are not only “quiet” ones, but they cover “holes” of the seismic network as well.

22. Automatic NOAIG Mw and Focal Mechanism determination using Strong Motion stations within MWNEAR and FMNEAR method (Delouis et. al. 2009, BSSA) Spectral estimation Grid search Waveform inversion

23. NOAIG Moment Tensor determination using Strong Motion stations: Routine analysis using ISOLA (Sokos and Zahradnik, 2007)

24. Local seismic networks (like the portable seismic networks) or strong motion arrays can be accommodated on the central system in real-time operational mode helping the operational role of NOAIG.

25. Seismic Network Sea-level Network Acquisition, Automatic Processing, Auto Reporting, Manual Verification, Publication SeisComP3 Sea – Level Soft TAT General Secretariat for Civil Protection Earthquake Planning and Protection Organization 24/7 Operational System at NOA - HLNTWC Tsunami Model Database GIS Platform Quake Alerting Alerting GTS via HNMO real time seismic data GFZ, INGV, ORFEUS, IRIS Earthquake and Tsunami Database UNESCO/IOC/ICG/NEAMTWS: CTWP, TNC, TWFP, EMO Other Publishing Tools Com Test Tools 12 3

26. Near future steps Continuous improvement of data storage and processing, towards a semi-automatic procedure, Determination of data dissemination policies (ex. web hosted database for registered access), Improvements on the use of the strong ground motion records in conjunction with the information from seismological and macroseismic networks. Reliable ground motion prediction equations and site effects Shake maps

27. Thank you for your attention