Fumarole temperature and gas concentrations at the Sulphur Cone monitoring site on the Southwest Rift Zone remain stable, but are slightly elevated from measurements from several weeks ago due to repositioning and servicing of instrument sensors during maintenance in mid-September by HVO field crews.
Source: USGS Volcano Update 3 October 2019 [less]

The Hawaiian Volcano Observatory (HVO) reported that "for the past several months, earthquake and ground deformation rates at Mauna Loa Volcano have exceeded long term background levels. An eruption is not imminent and current rates are not cause for alarm. However, they do indicate changes in the shallow magma storage system at Mauna Loa."
[less]

From the latest update: [less]

"HVO seismic and deformation monitoring networks have been recording near background levels of seismicity and ground motion at Mauna Loa Volcano for at least the last six months. These observations indicate that the volcano is no longer at an elevated level of activity. Accordingly, HVO is dropping the Mauna Loa alert level to NORMAL and the aviation color code to GREEN." [less]

Such relatively large quakes under active volcanoes can (but not necessarily must) be precursors of new eruptions if they are being caused by magma pressurizing rock and fracturing it on its way up. Whether this particular quake is in fact caused by magma movements is impossible to know a priori without further analysis.
Mauna Loa is statistically "due" for an eruption (its last having been in 1984) and increased seismic activity and inflation over the past years have indicated an ongoing period of unrest due to gradual magma recharge. [less]

According to HVO's latest update, earthquakes at Mauna Loa during the past week "occurred beneath the west and north flanks of the volcano mostly in the 5 – 11 km (3 – 7 miles) depth range. In addition, earthquakes are occurring in south caldera and upper Southwest Rift Zone at depths less than 5 km (3 mi).
Global Positioning System (GPS) measurements show deformation related to inflation of a magma reservoir beneath the summit and upper Southwest Rift Zone, with inflation occurring mainly in the southwestern part of the magma storage complex." [less]

"Earthquakes occurred beneath Mauna Loa's upper Southwest Rift Zone at depths less than 13 km (8 miles). Deformation data are still consistent with inflation of magma reservoirs beneath Mauna Loa's summit and upper Southwest Rift Zone." [less]

The last eruption of Manua Loa occurred in 1984.
The original report by USGS: [less]

The swarm was in the same region where earthquakes began to occur a year or more before Mauna Loa's 1975 and 1984 eruptions. A likely interpretation is that the most recent swarm is a sign that some magma has intruded at the base of the volcano.
It is certainly no sign of an impending eruption in the very near future, but suggests that Mauna Loa, which still is the world's largest ACTIVE volcano, on the medium term, continues to prepare itself for its next eruption. [less]

HVO reports in its monthly update:
"Minor inflation of a shallow magma reservoir beneath Mauna Loa may be occurring. Seismicity rates were slightly elevated. [less]

From the USGS report:
"Deformation: Deformation of Mauna Loa continued to be dominated by southeasterly motion of the south flank. However, slow, localized uplift also continues near the summit caldera (~1cm/yr at MLSP) suggesting that some inflation of the shallow magma reservoir complex beneath the summit area is occurring. [less]