  During its two years mission around comet 67P/Churyumov-Gerasimenko, ESA's
Rosetta spacecraft had the unique opportunity to follow closely a comet in the
most active part of its orbit. Many studies have presented the typical features
associated to the activity of the nucleus, such as localized dust and gas jets.
Here we report on series of more energetic transient events observed during the
three months surrounding the comet's perihelion passage in August 2015.
  We detected and characterized 34 outbursts with the Rosetta cameras, one
every 2.4 nucleus rotation. We identified 3 main dust plume morphologies
associated to these events: a narrow jet, a broad fan, and more complex plumes
featuring both previous types together. These plumes are comparable in scale
and temporal variation to what has been observed on other comets.
  We present a map of the outbursts source locations, and discuss the
associated topography. We find that the spatial distribution sources on the
nucleus correlates well with morphological region boundaries, especially in
areas marked by steep scarps or cliffs.
  Outbursts occur either in the early morning or shortly after the local noon,
indicating two potential processes: Morning outbursts may be triggered by
thermal stresses linked to the rapid change of temperature, afternoon events
are most likely related to the diurnal or seasonal heat wave reaching volatiles
buried under the first surface layer. In addition, we propose that some events
can be the result of a completely different mechanism, in which most of the
dust is released upon the collapse of a cliff.

Earth and Planetary Astrophysics