Observatories and Research Facilities for EUropean Seismology
Volume 3, no 1 June 2001 Orfeus Newsletter

 

Implementing real-time data exchange at the ORFEUS Data Center

Chad Trabant
ORFEUS Data Center, KNMI, Wilhelminalaan 10, 3730 AE De Bilt, The Netherlands
 

Introduction - Implementation
Status - Products - Acknowledgements - Reference

Introduction

One of the primary objectives within the MEREDIAN project is to provide (near) real-time event based waveform data to participants, the seismological community, and decision makers for seismological events in the European-Mediterranean area.  In recent years, significant investments in seismic networks have been made at the national level across the EuroMed area.  We are taking advantage of this fact in order to realize the goal of real-time cross border data exchange.  By developing the necessary procedures and technologies to facilitate real-time data streams from EuroMed national and regional network data centers we are creating a EuroMed virtual seismic network.  This will allow for very rapid availability of event based waveform data.  The ORFEUS Data Center (ODC) is the central collection point for this virtual network.

Implementation

One of the greatest challenges to building a EuroMed real-time virtual network is the different technologies in use at each regional and national network data center.  In order to address this heterogeneity, the ODC is working in cooperation with GEOFON to develop a protocol for real-time data transmission over the Internet known as the SeedLink Protocol.  The protocol is resistant to network outages and has many other advantages to other currently available protocols for both real-time and general seismic data transmission .  The SeisComP package developed at GEOFON currently implements the SeedLink Protocol for network communication between SeisComP nodes.  The idea is that SeisComP, or various components of SeisComP, can be implemented at many EuroMed data centers providing a uniform method of data transmission to the ODC (Hanka et al, 2000). The challenge then remains to develop the interface between the data and a SeedLink server at each data center.  While other data transmission methods will be used for real-time data exchange during the MEREDIAN project, development of the SeedLink Protocol and associated tools is now our primary focus.

In order to address virtual network heterogeneity on the collection end, the ODC has implemented the Antelope Environmental Monitoring Software package developed by Boulder Real Time Technologies, Inc.®.  This software package allows ODC to collect real-time data from a variety of different sources.  Furthermore, the package is capable of, and provides the capability to develop, a significant amount of automated data processing; including the production of event based data volumes.  Any MEREDIAN participant using Antelope can easily share their data with the ODC via built-in Antelope transmission protocols.  There are many other pre-existing methods by which MEREDIAN participants and non-participants can provide real-time data to ODC.  It is also possible to develop new interfaces for data submission if necessary.  An Antelope software module that allows the system to collect data using the SeedLink Protocol has been developed at the ODC.  This system gives the ODC a large amount of flexibility in collecting data from various sources and capability for rapid automatic processing.  Figure 1 is an illustration of the Antelope based real-time collection system being developed at the ODC.
 
 

Figure 1. A diagrammatic illustration of the Antelope based real-time seismic data collection system at the ORFEUS Data Center


Status

Currently in a testing phase, the real-time initiative at the ORFEUS Data Center is collecting broad band data from GEOFON, ZAMG, GSS, and the KNMI.  Data from 10 GEOFON stations are collected using the SeedLink Protocol.  Data from 1 GSS and 7 ZAMG stations are collected using Antelope built-in transmission protocols.  Data from the KNMI are collected from a ComServ system.  Over the next couple of years we are expecting a significant increase in the amount of data collected by the real-time system as we expand the virtual network.  As the network grows, information regarding the current status of the initiative can be found at http://orfeus.knmi.nl/meredian/realtime-status/.
 

Products

A EuroMed virtual seismic network will enable the ODC to provide waveform data very rapidly following an event.  All of the resulting data products will be available on-line through the familiar ORFEUS WILBER interface.  The exact timing of data availability has not be decided.  Potentially, a SEED data volume could be available within 5-15 minutes after an event.  A follow-up SEED volume, superseding the initial one, could be produced 1-5 days after an event.  This volume would probably be merged with data collected by other systems that have access to data that the real-time system will not, e.g. a Spyder®-like system.  Naturally, these initial data products will not be quality controlled, but the result of automated processing.  Finally, the data would go through a quality control procedure and be included in the normal electronic archive at the ODC. As necessary developments are completed we hope to eventually include data from most, if not all, of the MEREDIAN participants in the real-time initiative.  Furthermore, we would also like to include non-participants whenever possible.
 

Acknowledgments

We would like to thank GEOFON for cooperation in making needed software developments and for providing real-time access to data for many GEOFON stations.  And also, to ZAMG and GSS for generously providing us with their real-time data streams during the current testing phase. The MEREDIAN project is funded by EC contract EVR1-CT-2000-40007.
 

Reference



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