  We introduce a modification of the OFC earthquake model [Phys. Rev. Lett. 68,
1244 (1992)] in order to improve resemblance with the Burridge and Knopoff
mechanical model and with possible laboratory experiments. A constant force
continually drives the system, and thresholds are distributed randomly
following a narrow distribution. We find quasiperiodic behavior in the
avalanche time series with a period proportional to the degree of dissipation
of the system. Periodicity is not as robust as criticality when the threshold
force distribution widens; and foreshocks and aftershocks are connected to the
observed periodicity.
