  An Efimov trimer near the atom-dimer threshold can increase the atom loss
rate in ultracold trapped atoms through the {\it avalanche mechanism} proposed
by Zaccanti et al. A 3-body recombination event creates an energetic atom and
dimer, whose subsequent elastic collisions produce additional atoms with
sufficient energy to escape from the trapping potential. We use Monte Carlo
methods to calculate the average number of atoms lost and the average heat
generated by recombination events in both a Bose-Einstein condensate and a
thermal gas. We take into account the energy-dependence of the cross sections
and the spatial structure of the atom cloud. We confirm that the number of
atoms lost can be much larger than the naive value 3 if there is an Efimov
trimer near the atom-dimer threshold. This does not produce a narrow loss
feature, but it can significantly affect the determination of Efimov
parameters.
