  Radio and optical observations of the evolution of flare-associated phenomena
have shown an initial and rapid burst at 0.4 THz only followed subsequently by
a localized chromospheric heating producing an H{\alpha} brightening with later
heating of the whole active region. A major instability occurred several
minutes later producing one impulsive burst at microwaves only, associated with
an M2.0 GOES X-ray flare that exhibited the main H{\alpha} brightening at the
same site as the first flash. The possible association between long-enduring
time profiles at soft X-rays, microwaves, H{\alpha} and sub-THz wavelengths is
discussed. In the decay phase the H{\alpha} movie shows a disrupting magnetic
arch structure ejecting dark, presumably chromospheric, material upwards. The
time sequence of events suggests genuine interdependent and possibly
non-thermal instabilities triggering phenomena, with concurrent active region
plasma heating and material ejection.
