Armature | framework foundational elements; see infrastructure

Catalyst | A product that speeds up a process but remains unchanged [usually referred to in a chemical reaction]

Cultural Ecology | study of dynamic interactions and adaptations among humans and their environments

Decay | process of deterioration or decline from a more thriving condition; wasting away or becoming ruinous

Emergence | process of iterative interaction of unitary elements through simple governing rules, often producing unexpected organizational outcomes; process of self-organization

Hodology | geography_study of paths; philosophy_study of interconnected ideas; neuroscience_study of patterns of connections in the white matter of the brain [Trumbell, David. Maps Narratives and Trails.  Geographical Research, June 2007, p. 142.]

Greyfield | [in US + Canada] economically obsolescent, outdated, failing, or declining land or real-estate.

Infrastructure | a foundation or network crucial to the life of a city, either currently or in the past; i.e. utility systems, transportation systems

Interchange | The act of exchanging reciprocally; giving and receiving with reciprocity; reciprocal exchange (of commodities, courtesies, ideas, etc.) between two persons or parties; Alternate or varied succession in time, order, or space; alternation, vicissitude [OED]

Matrix | Elements that make up a system or interconnected network; a place or environment where a process begins, originates, or grows.

Mobility | ease or freedom of movement, capacity for rapid or comfortable travel, and ability of individuals within a society to move socially.

Parametric | a condition where parameters or rules govern relationships among elemental units within a system, producing an often uneşxpected outcome

Ruins | physical constructs under deterioration that are no longer used for its original purpose

Spelunking | hobby of exploring caves

Urban decay | deterioration of urban constructs both in physical and nonphysical sense; i.e. community moral, buildings, infrastructure

Urban spelunking | exploration of underground or often unseen [off-limits] part of decaying urban constructs [abandoned industrial or infrastructural sites]

Vicissitude | Alternation, mutual or reciprocal succession, of things or conditions; esp. alternating succession of opposite or contrasted things [OED]