  The Sachdev-Ye-Kitaev (SYK) model can be used to describe black holes (BHs)
in two-dimensional nearly-anti-de-Sitter gravity. We show that when such BHs
are perturbed by a time-dependent negative-energy perturbation, their interior
can be partially revealed. In the SYK model, a partial measurement of the state
of the Majorana fermion pairs allows one to construct a matching time-dependent
negative-energy perturbation of the BH geometry that shifts the state of the BH
away from its equilibrium state. Kourkoulou and Maldacena showed that, if the
perturbation is strong enough, the interior can be fully exposed and the BH
disappears. Here, we show that when the perturbation is weaker than the
threshold for full exposure, it effectively moves the horizon of the BH
inwards, thus partially exposing the interior of the BH and leaving behind a
smaller BH. The exposure is in proportion to the number of measured Majorana
pairs and so also in proportion to the magnitude of the energy of the
perturbation. From the boundary, the partial measurement is perceived as a
burst of radiation whose strength and duration are proportional to the number
of measured Majorana pairs.
