  The ubiquity of recently discovered low-amplitude decayless kink oscillations
of plasma loops allows for the seismological probing of the corona on a regular
basis. In particular, in contrast to traditionally applied seismology which is
based on the large-amplitude decaying kink oscillations excited by flares and
eruptions, decayless oscillations can potentially provide the diagnostics
necessary for their forecasting. We analysed decayless kink oscillations in
several distinct loops belonging to active region NOAA 12107 on 10 July 2010
during its quiet time period, when it was observed on the West limb in EUV by
the Atmospheric Imaging Assembly on-board Solar Dynamics Observatory. The
oscillation periods were estimated with the use of the motion magnification
technique. The lengths of the oscillating loops were determined within the
assumption of its semicircular shape by measuring the position of their
foot-points. The density contrast in the loops was estimated from the observed
intensity contrast accounting for the unknown spatial scale of the background
plasma. The combination of those measurements allows us to determine the
distribution of kink and Alfv\'en speeds in the active region. Thus, we
demonstrate the possibility to obtain seismological information about coronal
active regions during the quiet periods of time.
