  A generic feature of string compactifications is the presence of many scalar
fields, called moduli. Moduli are usually displaced from their
post-inflationary minimum during inflation. Their relaxation to the minimum
could lead to the production of oscillons: localised, long-lived, non-linear
excitations of the scalar fields. Here we discuss under which conditions
oscillons can be produced in string cosmology and illustrate their production
and potential phenomenology with two explicit examples: the case of an
initially displaced volume modulus in the KKLT scenario and the case of a
displaced blow-up Kaehler modulus in the Large Volume Scenario (LVS). One, in
principle, observable consequence of oscillon dynamics is the production of
gravitational waves which, contrary to those produced from preheating after
high scale inflation, could have lower frequencies, closer to the currently
observable range. We also show that, for the considered parameter ranges,
oscillating fibre and volume moduli do not develop any significant
non-perturbative dynamics. Furthermore, we find that the vacua in the LVS and
the KKLT scenario are stable against local overshootings of the field into the
decompatification region, which provides an additional check on the longevity
of these metastable configurations.
