Nucleation process in the Burridge-Knopoff model of earthquakes Yushi Ueda, Shouji Morimoto, Shingo Kakui, Takumi Yamamoto and Hikaru Kawamura EPL, 106 6 (2014) 69001 Published online: 23 June 2014 DOI: 10.1209/0295-5075/106/69001