Overview of the large scale GC region showing the features discussed in this work. The CMZ and five molecular clouds are indicated by the HCO⁺(1 − 0) emission from Riquelme et al. (2010b). Loops 1 and 2 are plotted in the CO(2 − 1) emissionfrom Kudo et al. (2011). Loop 1 is integrated in the velocity range − 180 to − 90  km s⁻¹ (blue contour), and loop 2 from − 90 to − 40  km s⁻¹ (red contour). The footpoints are indicated with the black ellipse. The green ellipse shows the M−3.8+0.9 molecular cloud studied in this work.