SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris Contribution of the Seismological Laboratory National & Kapodistrian University.

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

Contribution of the

Seismological Laboratory

National & Kapodistrian University of Athens

ATHENS TEST SITE

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

Site Data Method(s) Partners

Greece, Athens Strong and week motion network2 arrays

a) Tnow network based location approach b) Tc and Pd on-site calculation approach andc) Array based processing approach

NIED, NORSAR

ATHENS TEST SITE

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

KALI

AKOR

PLATLAKA

White: Seismographs in real-time transmission,

Red: Seismographs in offline mode,

Blue: Accelerographs in dial-up mode.

Strong & Weak Motion Network

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

Picking and associating phases

Network approach example

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

White: traditionally picked and located events

Black: automatic picked and associated events and Tnow located

Earthquake locations for earthquakes with M>3 for the period (September 2007 – March 2008)

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

The June 8 2008 (12:25 GMT), Andravida earthquake of magnitude Mw=6.4. Location and rupture zone

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

The calculated slip model revealed more than one seismic sources (Agalos A.)

Synthetic PGV map plus relocated seismicity (Papadimitriou et al)

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

recording at Rodini station

Instantaneous period estimation at Rodini station

Kanamori & Wu

2 s pre-rupture, period ~ 0,6 M=5.23 s period ~ 1.4 M=6.7

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

TRISAR and MALES arrays

• REFTEK DAS 72• CMG-40T-1s

• GURALP DM24 Mark III

• CMG-40T-30s

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

Array processing scheme developed by NORSAR and implemented by NKUA for the Athens test site

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

Andravida Mw=6.4 earthquake.

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

Array processing results for the June 6, 2008 Andravida Mw=6.4 earthquake.

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

Aftershock activity

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

February 4, 2008 M=5.0 earthquake

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

Array processing results for the February 4, 2008 M=5.0 earthquake

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

Limiting factors of array performance

• Temporary nature of installation• Timing errors resulting from the absence of a

common timing system• Complexity and variations of crustal structure in

the area.• Improvement of travel time tables or location

corrections according to azimuth• Further tuning of single and multi array location

algorithms is needed

SAFER Project final meeting, Potsdam, 3-5 June, 2009 Nicholas Voulgaris

Future prospects

• Continuation of EW algorithm testing using the increasing number of real-time stations becoming available near the test site area and installing accelerometers in tandem.

• Activating real time transmission of RASMON accelerometer network.• Improving latency times• Re-initiate array related activities provided that a common time base

system can be established.