PTWC
Pacific Tsunami Warning Center

Tsunami warning centers operated by NOAA in the United States.
USGS
The United States Geological Survey 

Latest earthquakes map and list elaborated by the USGS

GDACS
Global Disaster Alert and Coordinator System

Worlwide  disaster monitor for earthquakes, tsunamis, floods, volcanoes and tropical cyclones. 

GFZ
German Research Centre for Geosciences

Automatic GEOFON Global Seismic Monitor
NTWC
National Tsunami Warning Center  

Tsunami Warning Center operated by the National Oceanic and NOAA in the United States