T-PHASE DETECTION IN MEXICO’S SEISMIC NETWORK FROM PACIFIC RING OF FIRE EARTHQUAKES
The T-phase is a hydroacoustic wave generated by submarine earthquakes and some other sources. It propagates efficiently to great distances through the SOund Fixing And Ranging (SOFAR) channel. This signal provides a tool to better understand and characterize these submarine seismic events, and even correlate them with seismic tsunami generation.
In this work, seismograms from Mexico’s Servicio Sismológico Nacional (SSN) broadband network of continental stations near the Pacific coast were analyzed for events of magnitude 8 or greater with epicenters in the Pacific Ocean (e.g., Chile 2010, Tōhoku 2011, Kamchatka 2025), as well as other relevant events. The goal is to identify which continental stations in Mexico can detect T waves and also what areas of the Pacific Ocean generate T waves that can be recorded in Mexico. Additionally, Mexico’s SSN and the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) operate hydroacoustic station HA06 on Socorro Island in the Pacific Ocean. The island’s location allows for the optimal detection of T-phases from sources throughout the Pacific Basin. Data from station HA06 were analyzed for teleseismic events and for events in the Mexican subduction zone.
T-phases were detected for far-field events starting from Mw 6.9, including tsunamigenic events. T-phases from events in Chile, Japan, Philippines, Hawaii, and Fiji were recorded at continental stations in Mexico. However, T-phases were not recorded in Mexico from events with epicenters in Sumatra Indonesia, South Peru, Papua New Guinea and Solomon Islands. Detection was compared amongst the various stations in order to establish a correlation with epicentral distance and with the relative event locations, as well as specific station characteristics that influence detection.
Even though Mexico does not have dedicated hydroacoustic stations, records from Socorro Island show converted T-phase detection and continental stations record T-phases from teleseismic events. This opens the door to hybrid strategies evaluation (seismic + hydroacoustic + sea level) to strengthen detection and early forecasting for near-field tsunami generation.