EARTH
In the literature: open
How do locked crystal mushes become eruptible within decades?
In plain words
A mush that is mostly crystals cannot flow, yet crystal clocks show it can be turned into eruptible magma within years to centuries before an eruption. How that happens so fast is unclear.
Precise statement
Explain the rapid remobilization of crystal mush (crystal fraction above about 0.5) into eruptible magma on timescales of $10^{0}\ \text{to}\ 10^{2}\,\mathrm{yr}$ inferred from diffusion chronometry, distinguishing reheating by recharge, melt segregation by compaction or reactive flow, and gas sparging. An answer is a mechanism whose predicted timescale and volume match petrologic records of large eruptions.
What would settle it
Multiphase reservoir simulations, with measured mush rheology, that reproduce remobilization times and volumes inferred from crystal chronometry.