ABSTRACT
The adaptive capacity of any system is usually assessed by observing how it responds to disruptions or challenges. Adaptive capacity has limits or boundary conditions, and disruptions provide information about where those boundaries lie and how the system behaves when events push it near or over those boundaries. Assessing resilience requires models of classes of adaptive behavior. These models need to capture the processes that contribute to adaptation when surprising disruptions occur. The basic decompensation pattern evolves across two phases: automated loops compensate for a growing disturbance and a decompensation event occurs because the automated response cannot compensate for the disturbance indefinitely. Measures of brittleness and resilience will emerge when we abstract general patterns from specific cases of challenge and response. Resilience engineering needs to search out incidents because they reveal boundary conditions and how the system behaves near these boundaries.
