Subsea Cable Protection: Why Monitoring Needs to Start Before the Fault

WHAT HAPPENED TO THE PERTH SUBSEA CABLES?

Two subsea communication cables off Perth have suffered faults in quick succession, prompting an investigation and renewed scrutiny of activity around critical underwater infrastructure.

The Indigo West and Indigo Central cables, operated by SUBCO, experienced faults within the Submarine Cable Protection Zone off Western Australia. A vessel was reported operating in the area around the time of the incidents, although the cause of the faults has not yet been established. Australian authorities are now assessing the circumstances.

For the subsea industry, the story raises a bigger question:

How do you protect a critical cable when the warning signs appear before the damage does?

A PROTECTION ZONE DOESN'T PROTECT A CABLE ON ITS OWN

Designated protection zones are an important part of subsea infrastructure management. But drawing a boundary around an asset is only the beginning.

Marine environments are constantly moving. Fishing vessels, commercial shipping, anchoring, construction and other activity can bring vessels into proximity with critical infrastructure every day.

The challenge is identifying which activity matters, when it matters and what to do about it.

That requires more than a vessel appearing on an AIS map.

FROM MONITORING TO MARINE INTELLIGENCE

AIS provides visibility. Intelligence provides context.

A vessel entering a protected area isn't automatically a threat. Understanding its behaviour, activity, proximity to the asset and wider operating environment is what allows an operator to distinguish routine activity from potential risk.

This is where proactive protection becomes critical.

At Seagard, our approach combines:

Real-time marine intelligence
Understanding vessel movements and activity around critical subsea assets.

Risk detection
Identifying activity that may require investigation or intervention.

Marine liaison
Using specialist marine knowledge and established relationships to communicate with vessels and stakeholders operating in the area.

On-water protection
Taking the response beyond the screen when a situation requires physical intervention.

The objective is simple: identify potential threats early enough to do something about them.

THE COST OF WAITING

When a cable fault occurs, the impact extends well beyond the cable itself.

Asset owners can face service disruption, emergency repairs, vessel mobilisation, operational delays and significant financial exposure.

And once a fault has occurred, the options become considerably more expensive.

Prevention gives asset owners something a repair operation can't: time.

Time to identify a vessel.
Time to understand its activity.
Time to make contact.
Time to intervene.

IS YOUR PROTECTION STRATEGY PROACTIVE ENOUGH?

The Perth incidents are another reminder that subsea asset protection is moving beyond passive monitoring.

Asset owners should be asking:

• Can we see vessel activity around our critical assets in real time?
• Can we identify behaviour that presents a genuine risk?
• Do we know who to contact when a potential threat is identified?
• Can we intervene before an incident occurs?
• What happens between receiving an alert and taking action?

If the answer is simply "we monitor it", there may be a gap between visibility and protection.

Seagard: From intelligence to intervention

Seagard helps subsea asset owners move from knowing what's happening to acting on what matters.

Our combination of marine intelligence, specialist expertise, marine liaison and proactive asset protection helps identify and address potential threats before they become costly incidents.

Want to understand your exposure to subsea risk?

Talk to Seagard

RESOURCES

SubTel Forum - Subco Reports Concurrent Perth Cable Faults - https://subtelforum.com/subco-reports-concurrent-perth-cable-faults/

Marine Insight -Australia Investigates Damage To 2 Critical Undersea Communication Cables Off Perth https://www.marineinsight.com/australia-investigates-damage-to-2-critical-undersea-communication-cables-off-perth/

ABC News - Federal police urged to investigate 'concerning' subsea cable fault - https://www.abc.net.au/news/2026-08-11/subsea-cable-damaged-off-perth-coast-in-protection-zone/107021436

iTnews - AFP assessing report in connection with Perth cable faults - https://www.itnews.com.au/news/afp-assessing-report-in-connection-with-perth-cable-faults-628061