強震モニタ Extension is a Chrome add-on developed by minamix86. This free extension constantly monitors the earthquake activity and alerts users when an earthquake is detected.

Once installed, the extension runs in the background and automatically monitors the earthquake activity, even if the Strong Motion Monitor window or Chrome browser is closed. It is capable of detecting and notifying users about earthquakes, including those with low seismic intensities that may not be felt by humans.

During automatic monitoring, the extension can detect situations that may indicate an earthquake or receive emergency earthquake alerts. It offers several notification options, including automatic pop-up display of the Strong Motion Monitor, alarm sounds, voice notifications of the region and seismic intensity, desktop notifications, and automatic tweeting to Twitter. Each notification option can be individually toggled on or off.

For users who prefer using an Android app, a version called 強震モニタEx is also available.