How HERD fits into early warning (DART, ionospheric detection) instead of competing with it

Library → HERD and early warning

Every few years someone announces a gadget that will 'warn you of the next tsunami.' We won't. The real warning system is a layered, international machine — deep-ocean buoys, seismographs, tide gauges, warning centres — and it works. HERD's job is to add a layer that machine doesn't have: dense, cheap, local listening. We fit in; we don't replace.

How warning actually works today

Deep-ocean DART buoys detect the passing tsunami wave in the open sea1 and feed the data to official warning centres2; the system evolved over decades into an authoritative service3. It is — and must remain — the source of official alerts. Everything else only adds to it.

Infrasound and the ionosphere: the fast signals

Great earthquakes and eruptions radiate infrasound: the 2004 Sumatra earthquake produced infrasound recorded thousands of kilometres away4 5, and mesopause perturbations were proposed as a tsunami indicator6. Tsunamis and Lamb waves leave a signature in the ionosphere detectable by GNSS-TEC — from Sumatra 2004 to Tohoku 20117 and to Hunga Tonga 20228, where the eruption also drove fast Lamb-wave tsunamis worldwide9 10. These are complementary detections, not a replacement for buoys.

Where dense infrasound already warns — volcanoes and slopes

Operational infrasonic early warning already exists for explosive eruptions11, and a dense seismo-acoustic network warned of the 2019 paroxysmal Stromboli eruptions12. Infrasound arrays detect avalanches and estimate front velocity in real time13. These are exactly the local, fast-onset hazards a dense, cheap network is suited to.

HERD's layer

We add many local ears near coasts and volcanoes and hand the raw data to the same scientific community; consumer-scale networks have just proven themselves at planetary scale for earthquakes14. HERD is a research network and a data contributor — not a certified alarm. The official alert always comes from the warning centre; what we offer is coverage and minutes where the current system is sparse.

An honest caveat

We will never issue the official alert — that stays with the warning centres. HERD does not replace DART, seismographs or tide gauges, and promises no guaranteed warning. We add a data layer and coverage — nothing more.

Why this matters for HERD

A dense, cheap network doesn't compete with deep-ocean buoys — it lives in a different layer: close to the shore and the volcano, where minutes matter and official infrastructure is thin. We complement a system that already saves lives.

Sources for this article

organization NOAA PMEL / NCTR. DART (Deep-ocean Assessment and Reporting of Tsunamis) real-time network. nctr.pmel.noaa.gov
organization NOAA National Weather Service. U.S. Tsunami Warning Centers (Tsunami.gov). tsunami.gov
review Bernard E., Titov V. (2015). Evolution of tsunami warning systems and products. Phil. Trans. R. Soc. A 373(2053). doi.org
peer-reviewed Le Pichon A. et al. (2005). Infrasound associated with 2004-2005 large Sumatra earthquakes and tsunami. Geophys. Res. Lett. 32. doi.org
review Garcés M. et al. (2005). Infrasound associated with the 2004 Sumatra megathrust earthquake and tsunami. Acoustical Society of America. acoustics.org
peer-reviewed Bittner M. et al. (2010). Mesopause perturbations as a potential tsunami indicator. NHESS 10. nhess.copernicus.org
peer-reviewed Occhipinti G., Rolland L., Lognonné P., Watada S. (2013). From Sumatra 2004 to Tohoku-Oki 2011: systematic GPS detection of the ionospheric signature of tsunamigenic earthquakes. J. Geophys. Res. Space Physics 118(6). doi.org
peer-reviewed Ravanelli M. et al. (2023). Tsunami and Lamb-wave ionospheric signatures from the 2022 Tonga eruption. Pure Appl. Geophys. 180. doi.org
peer-reviewed Kubota T., Saito T., Nishida K. (2022). Global fast-traveling tsunamis driven by atmospheric Lamb waves on the 2022 Tonga eruption. Science 377. doi.org
peer-reviewed Matoza R.S. et al. (2022). Global seismoacoustic observations of the January 2022 Hunga eruption, Tonga. Science 377. science.org
peer-reviewed Ripepe M. et al. (2018). Infrasonic early warning system for explosive eruptions. J. Geophys. Res. Solid Earth 123. doi.org
peer-reviewed Ripepe M. et al. (2021). Dense seismo-acoustic network warning of the 2019 paroxysmal Stromboli eruptions. Sci. Rep. 11. doi.org
peer-reviewed Marchetti E. et al. (2015). Infrasound array criteria for automatic detection and front velocity estimation of snow avalanches. NHESS 15. nhess.copernicus.org
peer-reviewed Allen R.M. et al. (2025). Global earthquake detection and warning using Android phones. Science 389. doi.org