Mauna Loa

[sistersue]

I wonder if the scientists can forecast where the lava will probably go from studying the topography if/when there's an eruption.  Will it go on the same paths as last time (1984)?

[HereOnThePrimalEdge]

Mauna Loa can erupt from any side of the mountain, and from higher and lower altitudes.  Once scientists know from which side the outbreak takes place, and how high up it occurs, they will have a reasonably good idea which way the lava will flow.  The question then is, for how long a period will the lava erupt, which determines how far it will flow.

[MyManao]

I wonder if the scientists can forecast where the lava will probably go..

Sure, once it erupts you could predict where it will go yourself.. it’s pretty much as simple as it will go downhill. HVO was spot on during the 2018 eruption with their blue lined maps. But predicting where it will erupt before it does? Not this far from an event. And keep in mind, in the initial hours of an eruption if it's anything like it was in 1984, the whole mountain may rip open. Miles of fissures that can only be interpreted when most of them shut down and she erupts from a specific location.

As to where, and how frequently? I think the good ol’ Lava Zone Map tells the story in the simplest terms. That map, as tried and true as it is, clearly delineates the places most likely to host eruptions (Lava Zone 1), the places where the lava will most likely flow from there (Lava Zone 2), the places it might flow in the event of a long term event (Lava Zone 3), and the places where it is very unlikely to flow (Lava Zone 6). And you can see this at..

https://pubs.usgs.gov/mf/1992/2193/

Using the Lava Zone Map as a guide it's most likely the eruption will be at the summit or down one of the volcano’s two rifts. And, based on prior history, it’s more possible that if it goes to the west the lava that flows from the vents will impact the western slope, between South Point and Hookena, and be less likely to flow to the south.. towards Pahala and such. And that would be, no matter what, a disaster. Now, verses the last time the volcano erupted on that side in 1950, there’s too many people, and we can expect to have little warning, and there’s only one road.

If the eruption goes to the east side of the summit it is likely to repeat what it did in 1984. Erupt from the 9,000 foot elevation and send flows towards Hilo that will take weeks to get there. If at all. The least likely scenario, as with the western rift, is lava flows not heading towards Hilo but flowing to the south of the rift towards Upper Puna. 

Also, beyond the scope of the Lava Zone Map’s definitions there is a much rarer chance for an eruption outside of the predicted summit and rifts (Lava Zone 1) areas. So there are wildcards like the hotels on the North Kona side.. but that would take weeks to reach anything down that path.

[HereOnThePrimalEdge]

Map showing Mauna Loa, historic outbreaks (notated by year) and direction of lava flow:

https://www.usgs.gov/observatories/hvo/n...n-franklin

[MyManao]

As to predictions.. 

I find the two maps, the lava flow zone map I initially referenced, and the lava flow travel time map mr Edge posted a link to, seen side by side here..



Together tell an interesting story. 

When combined we see the USGS’s probabilities, which I assume the lava flow zone map (on the left above) is based on, rank the radial vents, as mapped on the other, flow distance/rate map (on the right), that fall outside the two rifts to be given a smaller probability. As such that area Northwest of Mauna Loa's summit, which sent a flow to the South Kohala coast in 1859, is mapped to be in a lower (LZ3 compared to LZ2) zone.

When we look at the current swarm of earthquakes, and focus on their distribution in the summit area as shown below, we see all the expected events in and to the Southwest of the summit caldera, and also a cluster, that is very shallow and has been persistent for quite a while, on the Northwest flank, outside and below the summit. Here is the quakes as mapped this morning, Thursday, 11/10/20022.



What I find interesting, not only is the existence of vents outside of the rifts, which are much more prevalent on Mauna Loa than Kilauea, but if this swarm is in anyway indicative of magma’s movement towards the surface then the possibilities for a calamity that has not been, until now, discussed, grows considerably.

Looking at that cluster of eqs, and the probable flow paths from an eruption if it were to happen at that location, as graphically shown by the flows that have come from that area in the past (as seen in the satellite view used as the earthquakes base map here), it seems to me that if an event were to occur there the entire Kealakekua to Capt. Cook area could be toast in short order.

[dobanion]

Yup, I see the same thing. IF it decided to do a radial eruption in the area of that cluster to the west of the crater, looks to me it'd head straight toward Kealakekua Bay, and FAST, given how steep it is throughout that area.

It's amazing how after few hundred years of no flows in an area, everything turns green, and you stop thinking about it. I have talked with several people who live in that area, and they don't seem to think Mauna Loa is a big threat. It's all the talk in Ocean View (where it's mostly still black rock).

We have this assumption that there will always be time to get out of the way of a lava flow, but it may not be so for everyone if it's a big eruption in the middle of the night with fast moving lava flows rolling down the steep side of Mauna Loa.

[Durian Fiend]

There was a community meeting organized by HVNP Nov 5 at Kealakekua to discuss Mauna Loa.
Haven’t heard any reports from it.

[Obie]

It's on youtube.

https://www.youtube.com/watch?v=A30Eke-ynBw