Geoscience Letters (Nov 2020)
Rebuild of the Bulletin of the International Seismological Centre (ISC)—part 2: 1980–2010
Abstract
Abstract The Bulletin of the International Seismological Centre (ISC) remains in demand for a wide range of geophysical studies. Users of the ISC Bulletin benefit from its long-term coverage, the most comprehensive set of measurements from the majority of permanent seismic stations and networks, and homogeneity of included parameters of earthquakes and other seismic events worldwide. Despite a reasonably conservative approach in preserving the operational procedures, changes are inevitable in order to achieve the best possible accuracy of published earthquake parameters. The last fundamental change in procedures has fully affected the data for years 2011 and beyond (Bondár and Storchak in Geophys J Int 186: 1220-1244, 2011). This is why it was decided to rebuild the earlier part (1964–2010) of the ISC Bulletin to achieve compatibility in earthquake hypocentres and magnitudes through its entire period. The first article on this project (Storchak et al. in Geosci Lett 4: 32, 2017) covered the period from 1964 to 1979, as it was publicly released. This article covers the remaining period from 1980 to 2010 with all seismic events re-processed and re-located in line with the modern ISC procedures, with ~ 489,000 new events, ~ 2600 new stations, ~15.5 million new seismic arrivals, and more robust and reliable mb and MS magnitude evaluations. We give statistics of departures in epicentre location and depth between the original and rebuilt ISC hypocentres. We also provide a summary for the entire rebuilt period (1964–2010). We give a brief account of events deleted from and added to the Bulletin, based on additional reports from permanent and temporary seismic deployments. We explain that newly re-computed (rebuilt) mb is on average larger that the original mb by 0.05 unit of magnitude. The rebuilt MS is only 0.01 unit larger that its predecessor. We announce that the entire reviewed part of the ISC Bulletin (1964–2017) is now based on the same velocity model, ak135, and the same earthquake location and magnitude computation procedures. Finally, we provide advice on how to obtain the original ISC Bulletin data, where necessary.
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