You may be surprised at the diversity of sensors that are able to detect seismic waves. Everything from the accelerometer in your cell phone to multi-million dollar satellites orbiting at altitudes of over 12,000 miles are capable of recording seismic vibrations. Surfers who visit the tsunami-prone Mentawai islands in Sumatra often invert an empty glass bottle on the floor before retiring, creating a very rudimentary ground-motion sensor in the absence of cell-phone coverage in that remote Indonesian region! This article will focus on three of the most ubiquitous seismic sensors in use today: broadband seismometers, strong-motion seismometers, and the Global Navigation Satellite System (GNSS).