JQuake is a Japanese earthquake monitoring application used to track seismic activity and display alerts from Japan's warning system. Within the app, different alert tones signal different levels of danger, and the major tsunami warning is among the most serious, reserved for large expected waves. Clips of the tone spread online through disaster monitoring streams, earthquake footage, and meme edits, partly because it sounds so stark compared with typical phone alerts. Its short length and unmistakable urgency have kept it in use as a reaction and prank sound.