Publication details
Enhancements of seismic detection capabilities resulting from the bilateral cooperation of the NDCs of Austria and the Czech Republic
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| Year of publication | 2009 |
| Type | Conference abstract |
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| Description | The cooperation between the Austrian and Czech National Data Centres (NDCs) has been in existence since the establishment of the CTBTO Preparatory Commission in 1997. Among the goals of the bilateral cooperation are the improvements of seismic events location accuracy in the Central European Region utilizing all data collected by both NDCs and readiness to support the CTBTO with supplementary data and information which are formally not part of the IMS data as needed for the IDC and IMS evaluations. Comparative studies of IDC and NDC event locations for the area of Austria and the Czech Republic have been carried out using the IDC event locations reported in the Reviewed Event Bulletins (REBs) for the period 2004 to 2008. In this period 29 tectonic events with local magnitude greater or equal to 3.0 were located by the Czech and Austrian NDCs within the area of interest. Due to higher seismicity in Austria there are more events from Austria than from the territory of the Czech Republic; the same pattern of more events from Austria is correctly reflected in the REB. The comparison revealed that only 17 of the 29 events were included in the REB, the remaining 12 events were not located by the IDC. Most events which were not reported in REBs had local magnitude smaller then 3.3, the highest local magnitude of an event not included in the REB was 3.7. The magnitudes of these missing events are generally below or close to the expected average global detection capability of the IMS seismic network. To assess the real IDC location accuracy 17 events have been analysed. These events were reported both in the REB and in the earthquake catalogues of the NDCs. Most events showed that a difference between the REB and NDC locations is smaller than 30 km, with an average difference of 18 km (median is 14 km). The largest difference occurred for an event at the Austrian/Hungarian border and amounted to 59 km. Only weak correlations have been found between the location difference and the number of stations detecting the event, the event magnitude, and the azimuthal coverage. Based on the Protocol to the CTBT the on-site inspection should be carried out in the area where the triggering event occurred, the size of the on-site inspection area should not exceed 1000 sq km. The area of 1000 sq km can be seen as an equivalent circle area with a radius of 17 to 18 km. Therefore the estimated location difference between the IDC and the NDC locations for the area of interest is at the edge of the uncertainty expected by the Treaty provisions for on-site inspection. |