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Cascade impact

A node's criticality is not its size but how much depends on it downstream. This layer measures that on the gas network by pure topology: for each node it walks the directed graph along the direction of transport and counts how many nodes would be isolated if that point went out of service. It is a measure of connectivity, not of flow.

Each node is sized by the number of nodes that depend on it downstream: orange for those concentrating more than half the maximum, gold for the middle, green for low impact. Source: reachability over the directed graph of the gas transmission network.

The nodes that concentrate the system

The head of the Neuquén basin dominates the ranking, fed by Vaca Muerta. Loma La Lata leads with 29 nodes stranded downstream; next come San Sebastián (28) and Magallanes (26), the far-southern nodes that channel austral gas toward the center of the country. That three points concentrate the connectivity like this is the operational definition of a single point of failure: they mark where an incident would cost the most, and therefore where to look first.

Why topology, not flow

Measuring criticality by the volume passing through each node would be richer, but it needs a reliable flow figure, and the available snapshot does not have one (see structure). Structural connectivity is poorer and more honest: it depends on no load number, only on how the network is wired. It ranks nodes by criticality, it does not predict the exact outage each would cause, which would depend on the reversibility of neighboring segments, on storage, and on alternate routes.

Limits of this layer

  • The model assumes transport follows the snapshot's source → target direction. Reversible pipelines break that assumption and would lower the criticality of the affected nodes.
  • It does not include storage, linepack, or import routes (LNG, Bolivia), which cushion the loss of a node.
  • It covers the gas network. The power grid is meshed and its criticality reads better as installed capacity, which is what sizes the generation nodes in the structure layer.

Structure and its impact are the physical surface. The known incidents are what has already happened on it.