Fig. 8

Example results of the forecasting experiment. The cumulative probabilities (black curves) of the occurrence of the next tremor after the reference time (00:00:00 on April 1, 2014) for the two groups in Fig. 2a, b are shown: a 34.20°N, 134.05°E and b 34.65°N, 136.55°E. The light-gray and dark-gray bands represent 68% and 95% prediction intervals for the timing of the next tremor events, respectively. The red vertical line shows the expected time of the next tremor event. The circles with vertical bars show the observed timings of the tremor events. The red circle indicates the next tremor event, which is the target of the forecast. c Comparison of the forecasted time (mean) of the next tremor events and the actual tremor times. d Percentage of the next tremor events that occurred within the 68% (orange) and 95% (blue) prediction interval, calculated for all groups. The dashed horizontal lines show the 68% (orange) and 95% (blue) levels. The gray bars show the daily number of tremor events in the forecasted groups