SAMUDRA: A Multi-Sensor Fiber-Optic Observatory for Real-Time Tsunami Early Warning in Indonesia

Indonesia is one of the world's most exposed tsunami-prone regions, yet it still lacks a fully operational early warning system capable of addressing non-tectonic sources such as submarine landslides and volcanic events — precisely the scenarios that can threaten coastlines with minimal reaction time. SAMUDRA (Submarine Alert Monitoring Using Dedicated Remote Advanced sensors) is a Franco-Indonesian project designed to address this critical gap by deploying an integrated multi-sensor fiber-optic observatory leveraging existing submarine telecom cable infrastructure.

The project combines three complementary optical sensing technologies: the LOKI optical interrogator (MAAGM), which enables all-optical, electronics-free remote sensing of point sensors including seismometers, pressiometers, tiltmeters, strainmeters and hydrophones; the CANOPUS system (Exail) for in-situ oceanographic measurements; and a Distributed Acoustic Sensing (DAS) system (FEBUS Optics) for continuous distributed measurements of strain, pressure, and temperature along the full cable length. All electronics remain onshore, ensuring robustness, low maintenance, and long-term reliability in harsh deep-sea environments — a key requirement for sustained operational monitoring.

This architecture directly addresses the core challenge of real-time monitoring in poorly instrumented offshore environments. The simultaneous acquisition of spatially distributed DAS measurements and high-precision point observations creates a multi-observable dataset enabling rapid discrimination between seismogenic, landslide-induced, and volcanic tsunami sources. Data processing pipelines, AI-supported event detection and scenario-based modelling are being co-developed with BMKG (Indonesia's national meteorological and geophysical agency) to produce operationally usable warning-ready products compatible with the existing InaTEWS warning chain — not a parallel system.

The project follows a staged deployment strategy: DAS measurements on the existing Rokatenda submarine cable (Flores) provide immediate data from an active seismogenic zone, while the main multi-instrument demonstrator is progressively built in Ambon Bay. Preliminary basin and dive tests (2026) will validate instrument-cable compatibility before full offshore deployment (Q1 2027, co-funded by ANR). The project is co-designed with BMKG and BRIN, ensuring local ownership and long-term operational sustainability — lessons drawn directly from the failure of post-2004 international aid deployments.

SAMUDRA exemplifies the new paradigm of exploiting existing fiber-optic infrastructure as a real-time geophysical observatory, with direct societal impact for tsunami early warning. Its scalable architecture is designed for replication across up to 50 priority sites in Indonesia, with broader applicability to other tsunami-exposed coastal regions worldwide.