Listric faults: Can they erupt and become a rift zone?

Kilauea Volcano is riddled with cracks and fault lines. Only a few of these cracks actively produce lava flows. When a fault line produces lava is called a "rift zone".  In May 2018, one crack caught my attention owing to earthquake activity. This crack is South of, and parallel to, the  East Rift Zone. The big question is whether lava will erupt from this area.

It should be noted that this blog originally referred the to crack as the "Great Crack" which is also a crack on Kilauea and located to the West in Ka'u. This crack is part of the Hilina Fault System and so is better referred to as being a Hilina crack. Even more specifically this is called a listric fault.  Cite: Instability of Hawaiian Volcanoes By Roger P. Denlinger and Julia K. Morgan

Above is view of  earthquakes on Kilauea volcano taken on May 23, 2018. The summit area is the cluster of earthquakes to the top left. The line of earthquakes of interest occurs as you can see parallel with the East Rift Zone. No lava has erupted to my knowledge in this area. However, there is evidence of parallel rift formations in the past, therefore, lava eruption from this crack may only be a matter of time.

The earthquake dot you see in blue, is detailed in the information box on the bottom left. The coordinates of this earthquake were as follows:

M 2.0 - 15km SW of Leilani Estates, Hawaii

Time

2018-05-23 21:25:02 (UTC+08:00)

Location

19.377°N 155.033°W

Depth

4.8 km

Using these coordinates, it was possible to map the area and then get a satellite view. The link to this satelllite view is https://www.google.com.ph/maps/@19.3344028,-155.1296463,687m/data=!3m1!1e3

When you zoom out you can see "The Great Crack"

Here is another section of the area of interest. This section is left (West) of the image above. It is zoomed in tighter so you can see the crack better.

Below is the area of interest zoomed out. You can see the East Rift Zone near the top and evidence of direct lava eruption. 

Lava flows into the crack

Notice the lava flow to the right. This is lava that came down from the East Rift Zone and notice what happened in the photo below when it reached his crack. 

So there is by the way the answer to the common question how do you stop a lava flow? A big crack in the path stopped part of the lava flow as seen here.

Listric faults are part of a slump

A listric fault is not exactly good if you live down slope of it. The land on one side of the listric fault is called a slump as shown in this graphic. 

You may have heard of the Hilina slump and claims the entire side of Kilauea from the East Rift and South could slump suddenly into the sea. These claims are exaggerated. The Hilina slump area is big, however, it is only 10% of the area as detailed in this article "Coast Guard in Hawaii - Is the 'Hilina Slump' about to break off?"

The mechanism involved with slumping is called gravitational spreading.  

It certainly doesn't look good for the land in the diagram above. Once an area begins to slump, there looks like one and only one inevitable future. For a volcano rising high above the seafloor, that inevitable future is a fast slide down to the seafloor.

Competing theory: Can a listric fault become a rift?

There is no question that some of the land that is part of the Hilina slump have already slumped significantly. However, as of yet, there has been very little slump associated with lands to the South of the crack that is of most interest. 

Could there be something else going on?  I believe the answer may be yes. In addition to lava pouring in from the top as seen in the photograph above, lava may be intruding into the crack from below. This type of lava rising up into a crack is called a lava dike. 

Great photographs of what a solidified lava dike looks like can be found here. 

I am not alone in the believe that a fault zone can become a new rift zone. Cite: Gravitational spreading and formation of new rift zones on overlapping volcanoes Thomas R. Walter et al. 

"Rifting and gravitational spreading are mutually coupled processes.."

These paper's authors believe new rift formation they documented go hand in hand with gravitational spreading. Of course the rift formation must occur on an active volcano.

Is lava intruding into the Hilina Fault System?

To help answer that question I have down loaded details of close to 3000 earthquakes for the month of May 2018. Many were associated with the summit and East Rift Zone. However, a large number were associated with the area specifically in question. 

Part of the answer to this question must come by figuring out what constitutes evidence of gravitational spreading, versus evidence of lava incursion and dike formation?

That is the real purpose of this blog and studying the seismograph printouts from the May 2018 lava incursion into the East Rift Zone near Leilani Estates.