The Unique Contribution of the International Data Centre Reviewed Event Bulletin to Global Seismicity Catalogs

Abstract

To monitor compliance with the Comprehensive Nuclear‐Test‐Ban Treaty (CTBT), the Preparatory Commission of the Comprehensive Nuclear‐Test‐Ban Treaty Organization (CTBTO) is setting up a network of 321 stations in the four verification technologies of seismology, hydroacoustics, infrasound, and radionuclides. Within this International Monitoring System (IMS) network are 170 seismic stations. The IMS seismic network is teleseismic in nature and designed to achieve approximately uniform coverage of the Earth for moderate sized events. A significant number of the IMS seismic stations consist of arrays of seismometers, adding to the network sensitivity and accuracy of the phase readings. At the end of the time period considered in this paper about 75% of the planned total of 170 seismic stations were certified and operational (www.ctbto.org/map). The data collected at the IMS network are transmitted through the Global Communications Infrastructure (GCI) in near real‐time or on request to the International Data Centre (IDC) in Vienna, Austria. Besides being archived and made accessible to Member States, these data are processed at the IDC and automatic and interactively reviewed bulletins are built. The moderate‐sized events detected by the IMS network are compiled in the IDC Reviewed Event Bulletin (REB), the final product of data analysis and interpretation. This bulletin is routinely produced and released to Member States since February 2000 on a daily basis with the exception of some 30 days (Koch, 2012) and contains nearly 30,000 events in the most recent years considered here. The International Seismological Centre (ISC) based at Thatcham, United Kingdom, prepares a global seismicity catalog that is a comprehensive summary of hypocenters and phase readings for all sufficiently large earthquakes. In this context the ISC aims to include all earthquakes in its bulletins that were recorded by one or more independently operated networks, to consistently re‐determine earthquake locations and magnitudes of events …