[S10-1] Development, testing and application of earthquake forecasting models

[S10-1-05] Reducing false alarms of annual forecast in the central China north-south seismic belt by reverse tracing of precursors (RTP)

^○Zhongliang Wu¹, Changsheng Jiang¹, Shengfeng Zhang^1,2 (1.Institute of Geophysics, China Earthquake Administration, Beijing, China, 2.Earthquake Administration of Shandong Province, Jinan, China)

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 such a consultation meeting, annual alarm regions are identified by an expert panel considering multi-disciplinary ‘anomalies'. 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)' proposed by Keilis-Borok is used to the annual consultation. 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' mapped by the pattern informatics (PI) algorithm, which targets at the five-year-scale seismic hazard, is considered. The ‘hit', or successful forecast, of the annual seismic hazard, is shown to be related to 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 year 2004 to 2012 show that using a threshold 17% can reduce 13 among 38 of the false-alarms without losing the successful hit (being 6 in that period).