Potential Mw8.1-or-above Japan earthquake before 2020 numerically predicted via ASF method

A prediction attempt for next potential Mw8.1-or-above earthquake in Japan before 2020 is presented in this work via addition-subtraction frequency (ASF) method. ASF method can be configured as a model of 3, 5 or 7 variables. This paper uses the historical date data of earthquake occurrence in Japan from 1854 to 2011, and transforms them into three forms [i.e., m/d/y (month/day/year), m/y (month/year), and y (year)]. After consistency analysis, ASF method indicates that the next Mw8.1- or-above earthquake most possibly happens on 7 December 2019.