Theory.
So, for roughly 800 years the cooled lava from the last eruptions held together what could be described as a"zip".
Gradually over the years the moving apart of the tectonic plates creates more and more tension until during a series of earthquakes the rock shatters and cracks and releases many hundreds of years worth of movement in one go.
For a few weeks magma rises, fills cracks, old lava tubes, and gradually fills up the system, occasionally we see short eruptions.
What we see now is that magma/lava attempting to fill the void left behind by the unzipping of the fault.
With the pressure released it no longer has a cap, and now just flows out, until a series of cinder cones, and enough weight of cooling lava is deposited on top to start to increase pressure on that flow at that particular point.
We could see this happen now across the peninsula at various weak faults fractures where land has collapsed or fractured as part of the pulling apart process, and at times quite lengthy eruptions in long lines like this.
This goes on for weeks, months or years until all possible weak spots are "glued up" and it all goes back to sleep for another approximately 800 years.
We see many comments which say the magma "pushes" it's way through and parts the fault, this is more like the fault moves apart and the magma comes up to fill the gap.
Tension rises, breaks and slides apart, volcanic activity fills and glues the fault together again, cools, tension rises, breaks and slides apart.... Rinse and repeat.