Combined measurements of extensive air showers at the surface and high-energy muons deep underground have been initiated at the Gran Sasso Laboratory. The underground detector is the first supermodule of MACRO (area = 140 ${\mathrm{m}}^2$, depth = 3100 m of water equivalent, $E_{\mu }>1.3\mathrm{}$ TeV) and the surface detector is the EAS-TOP array (altitude 2000 m above sea level, total enclosed area $A\sim {10}^5$ ${\mathrm{m}}^2$). We discuss the correlation technique, the comparison between the shower parameters as determined by the two detectors, and some of the characteristics of the reconstructed events.

• Received 12 February 1990

DOI:https://doi.org/10.1103/PhysRevD.42.1396