I think you need a refresher on statistics. If you think a 50% drop is likely, what then would be unlikely drop, 75% or 80%. A 50% drop is statisticly an unlikely event. Not an impossible event but highly unlikely. It would fall as an oulyer in any sort of standard deviation curve.
Mount Soledad is collapsing and it is not seeing this type of drop so I think your numbers are off.
