math_commands Monitoring earthquakes along mid-ocean ridges and oceanic transform faults is crucial for understanding magmatic and tectonic processes in oceanic regions. In this study, we present an automated envelope-cross-correlation-based workflow for detecting and locating submarine earthquakes using hydroacoustic T-phases recorded by cabled seafloor observatories in the Northeast Pacific Ocean. Our catalog comprises 25,681 earthquakes from 2015 to 2024, eight times more than the National Earthquake Information Center (NEIC) catalog compiled based on land-based seismic data, with approximately one unit improvement in magnitude of completeness. More than 7,000 earthquakes are located along the Juan de Fuca Ridge compared to the fewer than 100 events recorded in the NEIC catalog, with the majority concentrated along the northern segments suggesting that the higher spreading rate of the southern segments is accommodated through aseismic magmatism or smaller earthquakes below our detection threshold. Elevated seismicity along the West Valley, Endeavour, Cobb, and Coaxial segments possibly indicate active magmatic/volcanic processes, aligning with previous studies that identified swarms linked with diking/eruption events. Our catalog also captures significant seismic activity around the start of the 2015 Axial Seamount eruption. Finally, our catalog reveals numerous energetic swarms and mainshock-aftershock sequences along the Sovanco and Blanco Transform Faults, such as the 2021 Western Blanco swarm which includes 319 events potentially driven by aseismic slip or fluid migration. Therefore, our results demonstrate that the existing cabled seafloor observatories can be leveraged for improved real-time monitoring of earthquakes to facilitate the study of active magmatic and tectonic processes in the Northeast Pacific Ocean.