  Organizations in emergency settings must cope with various sources of
disruption, most notably personnel loss. Death, incapacitation, or isolation of
individuals within an organizational communication network can impair
information passing, coordination, and connectivity, and may drive maladaptive
responses such as repeated attempts to contact lost personnel (``calling the
dead'') that themselves consume scarce resources. At the same time,
organizations may respond to such disruption by reorganizing to restore
function, a behavior that is fundamental to organizational resilience. Here, we
use empirically calibrated models of communication for 17 groups of responders
to the World Trade Center Disaster to examine the impact of exogenous removal
of personnel on communication activity and network resilience. We find that
removal of high-degree personnel and those in institutionally coordinative
roles is particularly damaging to these organizations, with specialist
responders being slower to adapt to losses. However, all organizations show
adaptations to disruption, in some cases becoming better connected and making
more complete use of personnel relative to control after experiencing losses.
