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Early-est — methods & references
Real-time earthquake location & tsunamigenesis estimation. Discriminants (T50Ex, Td, T0, Td·T50Ex) and magnitudes (mb, Mwp, Mwpd) follow the Early-est method of Lomax & Michelini. Please cite the relevant works below.
Core method (A. Lomax & A. Michelini)
- Lomax, A., & Michelini, A. (2009). Mwpd: a duration–amplitude procedure for rapid determination of earthquake magnitude and tsunamigenic potential from P waveforms. Geophys. J. Int. 176(1), 200–214. 10.1111/j.1365-246X.2008.03974.x
- Lomax, A., & Michelini, A. (2009). Tsunami early warning using earthquake rupture duration. Geophys. Res. Lett. 36, L09306. 10.1029/2009GL037223
- Lomax, A., & Michelini, A. (2011). Tsunami early warning using earthquake rupture duration and P-wave dominant period. Geophys. J. Int. 185(1), 283–291. 10.1111/j.1365-246X.2010.04916.x
- Lomax, A., & Michelini, A. (2013). Tsunami early warning within five minutes. Pure Appl. Geophys. 170(9–10), 1385–1395. 10.1007/s00024-012-0512-6
- Lomax, A., Michelini, A., & Piatanesi, A. (2007). An energy-duration procedure for rapid determination of earthquake magnitude and tsunamigenic potential. Geophys. J. Int. 170(3), 1195–1209. 10.1111/j.1365-246X.2007.03469.x
Supporting methods & data
- Tsuboi, S., Abe, K., Takano, K., & Yamanaka, Y. (1995). Rapid determination of Mw from broadband P waveforms. Bull. Seismol. Soc. Am. 85(2), 606–613. 10.1785/BSSA0850020606 Mwp
- Bird, P. (2003). An updated digital model of plate boundaries. Geochem. Geophys. Geosyst. 4(3), 1027. 10.1029/2001GC000252 plate boundaries
- Data: GEOFON (GFZ), IRIS/EarthScope, GEOSCOPE (IPGP), Geoscience Australia — via SeedLink. Basemaps: Esri, GEBCO, CARTO/OSM.
Discriminants — what they mean
- Td (Tdom) — dominant period of the P wave (s). Scales with rupture size: small quakes ≈1 s, great earthquakes ≳10 s. Longer Td → bigger / longer rupture.
- T50Ex — “T50 excess”, dimensionless. How long high-frequency P energy persists vs. what a normal rupture of that size would give. High T50Ex = anomalously slow / long rupture — the hallmark of a tsunami earthquake (weak shaking, but a big tsunami).
- Td·T50Ex — tsunamigenic discriminant. Combines size (Td) and slowness (T50Ex). High value → large, slow, shallow rupture → high tsunami potential. This drives the Early-est warning colour (green → red).
- T0 — apparent P-wave source duration (s).
- mb / Mwp / Mwpd — body-wave / P-wave moment / duration-corrected moment magnitude. Mwpd best sizes great, slow, tsunamigenic ruptures (mb & Mwp saturate).
How to read the views
- Discriminant waterfall — rows = stations, time flows left→right (newest at right); each cell coloured by that station’s T50Ex. Mostly green = normal background. When a vertical band lights orange/red across many stations at once, that’s a coherent high-excess arrival — a candidate large / slow (tsunamigenic) earthquake. Hover any cell for the value.
- Tdom–T50Ex chart — each • is a station pick, each ◆ an event, plotted by Td (x) vs T50Ex (y); background shading = Td·T50Ex hazard zones. Picks/events drifting toward the upper-right (long period AND high excess) = tsunamigenic character; lower-left = ordinary tectonic.
- Tsunami decision factors (in each event) — mb/Mwp/Mwpd/Td·T50Ex vs. Early-est alert thresholds, plus depth, giving the warning level.
This deployment
Early-est 1.2.9 real-time instance & operational dashboard, agency net.comoglu (2026). Software: Early-est by A. Lomax / INGV. DOIs above should be cited for any scientific use of the discriminants or magnitudes shown here.