The USGS Hawaiian Volcano Observatory's improved seismic network began to detect increasingly frequent, small earthquakes on Mauna Loa as early as 2013. Renewed inflation of the volcano was detected by HVO's GPS network and also with Interferometric Synthetic Aperture Radar (InSAR) in 2014. Based on the elevated rates of earthquakes and persistent inflation, the Volcano Alert Level for Mauna Loa was elevated from Normal to Advisory on September 15, 2015.

According to the USGS Alert-Notification System for Volcanic Activity, an Advisory level indicates that the volcano is showing signs of unrest above known background levels, but does not mean that an eruption certain. Another period of Mauna Loa unrest in 2004–2005 included inflation and anomalous seismicity, but did not result in an eruption.