Reducing False Alarms of Annual Forecast in the Central China North–South Seismic Belt by Reverse Tracing of Precursors (RTP) Using the Pattern Informatics (PI) ‘Hotspots’

Abstract

The annual consultation on the likelihood of earthquakes in the next year, the ‘Annual Consultation Meeting’, has been one of the most important forward forecast experiments organized by the China Earthquake Administration (CEA) since the 1970s, in which annual alarm regions are identified by an expert panel considering multi-disciplinary ‘anomalies’. In such annual forecasts, one of the problems in need of further technical solution is its false alarms. To tackle this problem, the concept of ‘reverse tracing of precursors (RTP)’ is used to the annual consultation, as a temporal continuation and spatial extension of the work of ZHAO et al. (Pure Appl Geophys 167:783–800, 2010). The central China north–south seismic belt (in connection to the CSEP testing region) is selected as the testing region of such an approach. Applying the concept of RTP, for an annual alarm region delineated by the Annual Consultation Meeting, the distribution of ‘hotspots’ of the pattern informatics (PI), which targets the 5-year-scale seismic hazard, is considered. The ‘hit’, or successful forecast, of the annual seismic hazard is shown to be related to the sufficient coverage of the ‘hotspots’ within the annual alarm region. The ratio of the areas of the ‘hotspots’ over the whole area of the annual alarm region is thus used to identify the false alarms which have few ‘hotspots’. The results of the years 2004–2012 show that using a threshold of 17 % can reduce 34 % (13 among 38) of the false alarms without losing the successful hit (being 6 in that period).