I imagine most folks lost interest in the Kilauea eruption since the lava stopped flowing back on (or around) 28 Aug 2018. Since then, Kilauea has been relatively quiet; at least on the surface. Activity around the volcano has not stopped but the level of activity seems as though the southeast rift zone has run its course for the time being. 

Halema'uma'u (Kilauea's caldera crater) has seen its share of earthquakes both relatively shallow and down deeper. These are likely due to continued settling at the caldera proper. Overall activity has drastically dropped and catastrophic collapse events have stopped. As a result, Volcano National Park has reopened with both the USGS and National Park Services deeming the park safe enough for visitors to return (Yay!). A large section of Crater Rim Drive is inside Halema'uma'u rather than atop its rim. No word, yet, on renaming it Crater Drive (haha!). Sulfur dioxide gas is at a lower level than it has been for decades as well. Does that mean Kilauea is about to take a rest? Well, no one knows the answer to that question but one thing is for certain, the geological activity has only slowed but not stopped. Minor earthquakes continue though overall deflation of the crater seems to have halted. Steam and low gas emissions continue at the main crater, Pu'u 'Ō'ō and the southeast rift zone. Gas levels, remain low to non-existent at all locations.

Okay, so what? Well, Hawai'i (proper) is a system of volcanoes. Let us take a quick review of its volcanoes. Hawai'i consists of five different volcanoes (perhaps six someday*), only one is considered extinct. Starting at the northern end is Kohala which forms a peninsula at the island's northern tip (and is the extinct volcano -- last erupting 120,000 years ago). The hills and valleys of Kohala offer some of the most spectacular views Hawai'i has to offer. Incidentally, there is a fantastic view of Haleakala when cresting Kohala on Highway 250. The vista helps one appreciate the size of Haleakala given that you are seeing it from approximately 45 miles away and across the Maui Channel.  Then we have Mauna Kea measuring in at a mere 124 feet (38 M) taller than Mauna Loa.  Mauna Kea, dormant for 4500 years now, forms the bulk of northern and northeastern Hawai'i. To the northwest, Mauna Kea essentially overlaps with Mauna Loa. She poses no immediate threat and it could be several thousand more years before another eruption, or maybe never.  Next, we have the less predictable Hualalai volcano sandwiched between Mauna Kea and Mauna Loa on the western coast. Hualalai is the third most active Hawaiian volcano (in recorded history) and has contributed to Hawai'i's western land mass, particularly in the Kailua-Kona area. This volcano has remained quiet since 1801. Moving on, we have Mauna Loa. Yeah. Mauna Loa means long mountain in Hawaiian and this girl definitely lives up to that name. She makes up half of the island of Hawai'i. Half. The distance from southern shore, across the summit, to northeastern shore (near Hilo) is a staggering 120 Km! This massive shield volcano has an estimated 18,000 cubic miles of volume. If my math is correct, that volume is the equivalent of just over 70,000 Empire State buildings in cubic feet.** From base to summit she rises 17 Km (55,700') from the ocean floor -- easily dwarfing Mt Everest -- and her immense girth causes the ocean floor to sink an approximated 8 Km below the surrounding ocean bed. The 17 Km is accounting for the 8 Km dip she's causing, by the way. Were the ocean floor not sinking, Mauna Loa would be another (roughly) 8000 meters above sea level -- putting her at over 12,000 meters above sea level (4000 meters taller than Mount Everest).  She is a big girl and she is not dormant but not actively erupting either. Lastly, we have Kilauea, the youngest and most active volcano that makes up Hawai'i. This "young" lady forms most of the southern and southeastern end of the island. Kilauea has been actively erupting for 35 years and she is one of the world's most active volcanoes. Now that we have an overview of the Hawaiian volcanoes we will dive into the current situation.

Mauna Loa has been slowly and consistently building up energy since her last eruption in 1984 which was coincidental to Kilauea's 1983 eruption. In fact, it is possible Kilauea has been "stealing" energy from Mauna Loa all these years -- acting as a sort of release valve. A fault system exists between the two volcanoes and no concrete evidence exists to prove the two connect; however, circumstantial data suggest a possible relationship. We are still in early stages of a possible quiet period for Kilauea but, interestingly, Mauna Loa started to show increased activity, if only for a brief period, shortly after the Halema'uma'u collapse and the southeast rift zone eruption ceased. Check out Discover's Rocky Planet blog for a really well written post which includes a time-lapse of Halema'uma'u collapsing. Personally, I think it's a suggestion (again, not evidence) of linkage between the two volcanoes -- somewhere deep down in the plumbing. I'm not the only person to wonder this; in fact, I don't even have an original idea here.  It's also interesting to note that historically the island's volcanoes have typically not erupted concurrently with a couple of exceptions. And since 1924, with the exception of 1984, Kilauea and Mauna Loa have alternated in active eruptions. That may not sound like very long but historical records of Hawaiian volcano eruptions only go back maybe 100 years before that. Either way, not a definitive data set.

Meanwhile, Kilauea is "quiet" BUT, the southeast rift zone has been showing signs of inflation for several weeks. Nothing like what we saw prior to the eruption during the summer of 2018; just a slow, steady increase. Pu'u 'Ō'ō continues to steam heavily (particularly after rain) but has minimal outgassing. The crater also still experiences minor collapse events one of which occurred today. Halema'uma'u also shows similar signs of steam and little outgassing; but no apparent inflation.  

Minor Collapse Event DustDust from a minor collapse event at Pu'u O'o crater is captured on the webcam overwatching the main crater.

I am NOT suggesting an imminent eruption of Mauna Loa. There is absolutely no evidence to support such a claim. I am suggesting, however, that if Kilauea remains quiet for a period of time -- many, many months to years -- then we should expect to see a resurgence of Mauna Loa. Kilauea is not really showing signs of taking a nap at the moment though. Seismicity remains slightly elevated and as mentioned inflation is occurring along the rift zone but minimally. That said, my money is on Mauna Loa releasing some pressure before Kilauea does anything significant; assuming activity stays at current levels or declines. Kilauea, just released significant volumes of lava and it will take some time for that pressure to rebuild. Not to mention that the collapse events at the caldera may be significantly impeding further magma flow anywhere else within Kilauea's plumbing. This also does NOT suggest that Mauna Loa will have some sort cataclysmic eruption. More likely, she relieves pressure through vents resulting in outgassing of  SO2, steam, and some non-trivial amount of lava. In the meantime, Kilauea keeps building pressure. My, long game, theory is that Kilauea is the next star in the show of the multi-millennial dance we have been able to understand on the Hawaiian Islands. Kilauea continues to build the island and, perhaps, eventually she gives way to Lō'ihi. For the short game, Mauna Loa increases in activity with some sort of eruption before Kilauea returns to the spotlight.

Just so no one thinks I'm some conspiracy nut job I am including some seismic maps during the latest Kilauea eruption and then seismic activity from 29 Aug to today. You can replicate these maps by going to this site at the USGS.

03-May-03-JunSeismic activity on Hawai'i during the 2018 Kilauea eruption.

The first month of the 2018 eruption activity on LERZ. This is about 13,000 earthquakes of 1.1 or greater magnitude. Note that Mauna Loa shows some activity but pretty limited. Date range is 03 May to 03 June.

04-Jul-30-JulSeismic activity during the month of July -- 04 through 30 July during the 2018 Kilauea eruption even of Kilauea.

Seismic activity during the month of July which does show some activity on Mauna Loa; however, there were nearly 17,000 earthquakes that month. Note the cluster of earthquakes outside the national park on Mauna Loa's northwest slope. This is about the time that the LERZ is starting to stabilize (also not the drop in seismic activity along the LERZ compared to May). I skipped June because it showed almost no activity around Mauna Loa and a similar map around Kilauea as May.

Last 90 daysLast 90 days (end of August to 25 Nov) of seismic activity.

The last 90 days of seismic activity on Hawaii. Granted, this is a larger sample set (in terms of time) but notice the clusters of earthquakes at Mauna Loa's summit and northwest face. It is slightly higher activity than normal background activity. The (slightly) elevated activity coincides with the stoppage of activity at Kilauea. This data set contains about 900 earthquakes compared to almost 17,000 in the previous map. (M1+)

*There is currently a submerged volcano called Loihi which is about 21 miles south of Hawaii. It's possible that Loihi, Mauna Loa, and Kilauea expand enough that Loihi will become the sixth volcano on the island. Or it may become its own distinct island or fail to break the surface of the ocean at all. It will likely take tens of thousands of years for the answer to reveal itself.

**Figuring the 18,000 cubic miles for Kilauea and then taking the volume of the Empire state building -- converting Kilauea to cubic feet (an astronomical number) and then dividing that number by the volume of the Empire State building arrives at about 71,000 buildings to equate to Mauna Loa. Even if I''ve screwed up my math and I'm off by some order of magnitude -- that's still a crap ton of Empire State buildings. Wow.