Strong ground motion monitoring in Greece in Greece. D I Dr. - - PowerPoint PPT Presentation

NATIONAL OBSERVATORY OF ATHENS INSTITUTE OF GEODYNAMICS P.O.BOX 20048, 11810 ATHENS

Strong ground motion monitoring in Greece in Greece.

D I i S K l

• Dr. Ioannis S. Kalogeras

Research Director

The strong ground motion networks in Greece

• There are 3 main Institutions in Greece operating strong motion instruments at a national

scale: Institute of Geodynamics, Nat. Observatory of Athens (NOAGI) installations mainly at urban sites Institute of Engineering Seismology & Earthquake Engineering (ITSAK) Institute of Engineering Seismology & Earthquake Engineering (ITSAK) installations mainly at urban sites Public Power Corporation (PPC) installations at dams and thermoelectric plants installations at dams and thermoelectric plants In total, about 200 instruments are in operation in Greece This means a variety of instruments and aims, thus a difficulty in cooperation: Overlaps exist between NOAGI and ITSAK. PPC needs help from NOAGI and ITSAK for maintenance and data processing. However, efforts exist, resulting to common databases, common reports for strong earthquakes, communication for new installations.

The NOAGI strong ground motion network

The deployment started back to the 70s, while today consists of 78 installed instruments. Information is available at: Information is available at: http://www.gein.noa.gr/English/new-accelnet-eng/INTRODUCTION.htm The majority of the instruments are installed in urban areas taking into account the The majority of the instruments are installed in urban areas taking into account the seismicity and the urban development, while there are some of them installed at special constructions (dams, Athens metro) and at archaeological sites.

Present situation of NOAGI strong motion network

From 70s to nowadays From 70s to nowadays

Local arrays have been implemented with the support

• f
• ther
• rganizations

the support

• f
• ther
• rganizations

(municipalities, public organizations etc).

The records are processed routinely (following the Kinemetrics’ software) and the results are published in printed and electronic formats and the results are published in printed and electronic formats (Stavrakakis et al., 1992; Kalogeras & Stavrakakis, 1995, 1998, 2001, 2007). Strong motion databases have been developed under MsAccess for an easier manipulation of the available data.

Table relationships

Table contents

It is worth to mention the developement of a unified strong motion database (HEAD v1.0) in cooperation with ITSAK and Geophysical ( ) f f Laboratory (Thessaloniki) including records from the networks of the two Institutions processed in a homogeneous manner. I t t l 677 3 t d f In total 677 3-component records from 319 earthquakes are included in HEAD, covering the period 1973-1999 covering the period 1973-1999. Relocation

• f

the events, a homogeneous filtering technique, a g g q viewer and a query machine under MsAccess and new more reliable tt ti l ti hi th attenuation relationships were the “products” of this database.

Institute of Geodynamics and SYZEFXIS y

SYZEFXIS (meaning “linked together” in Greek) is financed by E.U. and Hellenic State and is implemented by the Society of Information S.A., under the Ministry of Internal Affairs. The budget of the project has been approved till 2013 (www syzefxis gov gr) (www.syzefxis.gov.gr). The hardware (routers, modems, call centers etc.) is given to the Institutions and Organizations for free and there is a Help Desk and a Forum for support on any Organizations for free and there is a Help Desk and a Forum for support on any subject concerning the network. Within the project all the Prefectures, Municipalities, Ministries, Hospitals and Within the project all the Prefectures, Municipalities, Ministries, Hospitals and Health Centers, Police stations, Fire Brigade etc. are linked and take advantage of a wide range of services (data transfer, VOIP, web pages hosting, PKI and SSL, t l f i d ti t ) teleconferencing, education, etc.). Institute of Geodynamics was the first seismological institution that joined the network covering in such a way a new subject in the frame of Syzefxis network, covering in such a way a new subject in the frame of Syzefxis.

Institute of Geodynamics & Syzefxis y y

TOWN HALL KASTELLORIZO OTE KASTELLORIZO LAN 2 Mbps/ 512kbbs KASTELLORIZO NATIONAL OBSERVATORY OF ATHENS Router 2 Mbps/ SDSL

4

2Mbps ATHENS 2 – 34 BUILDING WITH SYZEFXIS CONNECTION VPN1, VPN2, …. LAN Router Mbps Router ΣΥΖΕΥΞΙΣ

SYZEFXIS NET

LAN PBX

PSTN PSTN/ ISDN

2Mbps REMOTE ADSL

1 2 3

Use of different techniques:

leased lines, radio links, internet connection, combinations etc.

Establishment of a system for the telemetric maintenance f th t k

• f the network

The effort aimed to provide the necessary hardware and software in order The effort aimed to provide the necessary hardware and software in order to enhance “traditional” accelerographic instruments equipped with serial interfaces and exhibit various operational characteristics with modern f f network functionality. This requires not only several upgrades in terms of physical interconnections but designing and implementing the necessary intermediate software modules as well. intermediate software modules as well. Since routing and firewalling issues should be solved appropriately, a Central Controller Entity (CCE), hosted in a computer in NOAGI premises, in order to communicate fluently with each remote instrument, one-by-one.

The role of the CCE entity includes several modules The role of the CCE entity includes several modules concerning different purposes:

• Software driver modules are used for the CCE entity to directly communicate with

each remote serial device via the established IP connection and to download the serial i f ti i TCP/IP k t information via TCP/IP sockets.

• A main daemon is responsible to pass any necessary command to the accelerograph
• f interest or to listen to any activity or response from the remote instrument. Thus the

daemon acquires the operating status of the instrument, downloads any new event recorded and stores the information into appropriate log files.

• A separate module synchronizes the clocks of all the instruments using an accurate

p y g time reference from a GPS-equipped accelerograph, since the instrument maintenance in real-time conditions and the processing of the records are crucial for the network

• perational reliability
• perational reliability.
• All the gathered information (operational status and records) is available for web

access and/or further arithmetic post processing via modules that are implemented separately on a second computer which is hosted in the NOAGI premises separately on a second computer, which is hosted in the NOAGI premises.

Network #1

Accelerograph

• f type A

Interfacing Device Accelerograph

• f type N

Interfacing Device Monitoring Computer

…

Logs

…

Accelerograph

• f type A

Interfacing Device Commands Accelerograph

• f type N

Interfacing Device Web Server

Network #K

The status report of the instruments

Only the instruments denoted by black triangles are not connected and they are planned to be in the near future .

Deployment of a local dense strong motion array - Athens array Athens array

Started in 1996 with 10

• instruments. Today includes 27

digital instruments digital instruments. During 1999 Athens seismic sequence gave a database of q g more than 300 records. Recently, two intermediate

• depth

earthquakes recorded (2006, M=6.9 and 2008, M=6.5) from a distance of 200km.

Athens earthquake (7/9/99, M=5.9), Surface, near-field Kythira earthquake (8/1/06, M=6.9), Intermediate depth, long distance , p , g Pga between 75 and 318 mg, for distances between 20 and Pga between 5 and 20 mg, for distances around 200km distances between 20 and 35km. distances around 200km.

1000 1000 100 100 10

PGA cm/s/s

10

PGA cm/s/s

1

P

M=5.0 M 6 0 1

P

S=2 S 1 0.1 M=6.0 M=7.0 PGA (horizontal components) +/-s 0.1 S=1 S=0 PGA (horizontal components) +/-s 1 10 100

R km

1 10 100

R km

Comparison of recorded pga during Athens 1999 earthquake with Skarlatoudis et al Comparison of recorded pga during Athens 1999 earthquake with Skarlatoudis et al. (2003) relations, according to magnitude and soil conditions. The higher values refer to the closest to the epicenter site (SPLB) which is located at alluvium deposits.

The lower values of pga for 2006 earthquake (M=6.5) compared to Youngs et al. (1997) relations could be attributed to the higher attenuation at the internal part of p the Aegean arc. Again the higher pga recorded at SPLB site.

Athens’ Acropolis Array

NOAGI and the Acropolis Restoration Service (YSMA) have been cooperating for the strong ground motion study since 2006 ground motion study since 2006. Within this frame, a digital 12bit accelerograph has been installed and connected via SYZEFXIS network for telemetric maintenance and data download. Since the Acropolis hill is exposed to extreme weather conditions (snow, p ( , heavy rain, low or high temperatures) special care has been taken for the reliable operation

• f the instrument
• f the instrument.

The accelerograph recorded two long distance earthquakes, namely that of Andravida q y (8/6/2008, M=6.5, R=195km, pga=0.006g) and that of Mantoudi (14/10/2008, M=5.6, R=100km, pga=0.004g), which are the first R 100km, pga 0.004g), which are the first recordings at the Acropolis archaelogical site ever.

Since 2008, NOAGI has undertaken the project "Developement of a strong ground motion array at the Acropolis site", within which 5 digital 24-bit CMG-5TD y p , g accelerographs have been purchased and installed. Moreover NOAGI included in this array the already installed accelerograph A800 and another one CMG-5TD purchased by YSMA purchased by YSMA. The accelerographs were installed on small, recently constructed vaults, at sites selected according to criteria of the broader cover of the hill, the monuments under investigation and the ground classification investigation and the ground classification. The accelerographs are connected to the network by wired or wireless connection at Acropolis hill and Acropolis hill and furthermore to YSMA

• ffices at Plaka, while

SYZEFXIS network is SYZEFXIS network is used for the instruments to be t l i t d remotely maintenanced from NOAGI premises.

Athens’ Acropolis Array Connections

Athens’ Acropolis Array status

Near f t re steps Near future steps

• Continue the TCP/IP connections, together with the

t i / d f th t k extension / upgrade of the network.

• Improvement
• f

the software for the near-real-time Improvement

• f

the software for the near real time instrument maintenance and data acquisition and processing. U f th t d ti i f ti i j ti

• Use of the strong ground motion information in conjunction

with the information from seismological and macroseismic t k networks.

A future perspective of NOAGI’s Network, within the frame of the National Strong Motion Network (NOAGI + ITSAK)

E PPO fi i ll

National Strong Motion Network (NOAGI + ITSAK)

E.P.P.O. financially supports this project, aiming to at least duplicate (at least) the number of instruments, covering large cities g g and seismically interesting sites with more than

• ne

more than

• ne

instrument, at different geological and topographic conditions topographic conditions.

Thank you for your attention