M. Manganaro, C. Schultz, P. Colin, I. Vovk, D. Mazin, for the MAGIC Collaboration
M87 is the first radio galaxy detected in the Very High Energy range (VHE, E > 100 GeV), located at a distance of 16 Mpc. The structure of its relativistic plasma jet, which is misaligned with respect to our line of sight, is spatially resolved in X-ray, optical and radio observations. For nearly a decade, along with these wavelengths, M87 has been monitored in the gamma-ray band by the ground-based Cherenkov telescopes such as MAGIC, and the space-born Fermi-LAT. The time correlation between the TeV flux and the emission at different wavelengths provides a unique opportunity to localize the gamma-ray emission process occurring in its active galactic nucleus. In 2005, 2008 and 2010, M87 underwent several periods of TeV activities, and rapid flares with short timescale (down to a rise time of less than a day) variability were detected. MAGIC continued to monitor M87 but no major flares were detected since 2010. From 2012-2015, we have collected ~156 hrs of data with MAGIC, resulting in a significant detection of the source in quiescent state in each year. The flux detected is the lowest observed since 2005. Here we present the combined GeV-TeV gamma-ray spectrum up to ~10 TeV as measured by MAGIC and, quasi-simultaneously, by Fermi-LAT. We discuss the emission variability of the MAGIC and Fermi-LAT light curve on daily and monthly timescales. We also address the possible mechanisms responsible for the GeV-TeV emission of the source and processes in the plasma of the jet.