  We examine the consequences of a model in which relativistic jets can be
triggered in quiescent massive black holes when a geometrically thick and hot
accretion disk forms as a result of the tidal disruption of a star. To estimate
the power, thrust and lifetime of the jet, we use the mass accretion history
onto the black hole as calculated by detailed hydrodynamic simulations of the
tidal disruption of stars. We go on to determine the states of the interstellar
medium in various types of quiescent galactic nuclei, and describe how this
external matter can affect jets propagating through it. We use this
information, together with a two-dimensional hydrodynamic model of the
structure of the relativistic flow, to study the dynamics of the jet, the
propagation of which is regulated by the density stratification of the
environment and by its injection history. The breaking of symmetry involved in
transitioning from one to two dimensions is crucial and leads to qualitatively
new phenomena. Many of the observed properties of the Swift 1644+57/GRB 110328A
event can be understood as resulting from accretion onto and jets driven by a
$10^6 M_\odot$ central mass black hole following the disruption of sun-like
star. With the inclusion of a stochastic contribution to the luminosity due to
variations in the feeding rate driven by instabilities near the tidal radius,
we find that our model can explain the X-ray light curve without invoking a
rarely-occurring deep encounter. In conjunction with the number density of
black holes in the local universe, we hypothesize that the conditions required
to produce the Swift event are not anomalous, but are in fact representative of
the jet-driven flare population arising from tidal disruptions.
  [abridged]
