Field-proven experience of Tsunami Early Warning Systems (TEWS) in the Pacific and Future Arrays in the Mediterranean: Increased Warning Times and Data Availability

Tsunami Early Warning Systems (TEWS) require rapid data collection, transmission and interrogation to ensure accurate and effective warnings are distributed to the public and critical infrastructure through tsunami warning centres.

MSM Ocean and Sonardyne formed a partnership to produce commercial-off-the-shelf (COTS) systems using standardised equipment. Modular, dual-redundant and field-proven systems provide operators with cost-effective, reliable and flexible deployment options with familiar existing support structures.

Each individual systems consists of a Sonardyne Bottom Pressure Recorder (BPR) and acoustic communication link to an MSM surface buoy with satellite communications to an onshore data centre. Onboard data processing reduces communication latency and therefore increases warning times. Predictable and infrequent maintenance schedules ensure these systems have high MTBF and low downtime, presenting less risk to the public.

We present case studies of current and planned TEWS in the Pacific and Mediterranean with associated tsunami events for context.

The Oceanographic Institute of the Navy (INOCAR, Ecuador) operates two arrays of Sonardyne-MSM TEWS systems located ~100km off the mainland and Galapagos Islands respectively. These arrays routinely detect sea surface height disturbances caused by events throughout the Pacific including earthquakes and volcanic eruptions.

Alerts were issued less than 60 seconds from initial seafloor BPR detection following the 2022 Hunga Tonga volcanic eruption and 2021 Mw 8.1 Kermadec Islands earthquake. At typical offshore tsunami velocities, extensive warnings and (crucially) responses to those warnings are possible with the geographic distribution of the TEWS array.

The National Institute for Geophysics and Volcanology (INGV, Italy) will install a TEWS array in the Ionian Sea in 2025 with spare units on land to achieve minimum downtime during planned maintenance in collaboration with MSM and Sonardyne. This is a key benefit of a cost-efficient and uncomplicated COTS solution.

Integration of buoys into a pre-existing network requires location optimisation to achieve maximum warning times. In this case, INGV has calculated a pair of buoy locations by minimising the cost function (maximising warning time) of several parameters including known tsunamigenic sources, associated tsunami spatial and temporal evolution, the severity and probability of such events and the existing contributions from coastal tide gauges to any alerts. The addition of offshore Sonardyne BPRs, with an acoustic link to MSM surface buoys is far more cost efficient than proposed cabled solutions.

Combining pre-existing and reliable infrastructure with additional new offshore equipment provides both the Pacific and Mediterranean coastlines with a significant increase in warning times and data availability.