Japan Wrongly Issues 9.9 Magnitude Earthquake Alert After 6.9 Quake in Russia

Japan's automatic earthquake early warning system wrongly estimated the magnitude of an earthquake in Russia as 9.9 and issued an alert, which was withdrawn within minutes. The error has raised questions about the system's reliability.

What happened

On Friday afternoon, 16 October, Japan's automatic earthquake early warning system, run by the Japan Meteorological Agency (JMA), indicated an exceptionally powerful earthquake. The initial estimate put its magnitude at 9.9. The alert was sent to mobile phones and public warning systems, warning people in several areas of possible danger.

However, the initial estimate was wrong. Officials rechecked the data and withdrew the warning within minutes. It was then confirmed that there was no threat of a tsunami.

The actual earthquake in Russia

According to the United States Geological Survey (USGS), the actual earthquake struck Russia's remote Kamchatka Peninsula. Its magnitude was recorded at 6.9, with the epicentre northeast of Ozernovsky. The depth was about 135 kilometres, according to the USGS.

Light tremors were felt in the northern Japanese city of Hakodate, while no major impact was reported from other parts of the country. The wide gap between the actual magnitude and the initial warning has raised questions about the automatic calculation process.

System was strengthened after 2011

The lapse carries added weight because Japan invested heavily in strengthening its disaster management system after the devastating Tohoku earthquake and tsunami of 11 March 2011. That disaster caused heavy loss of life and widespread destruction in coastal areas.

Japan's early warning system tries to detect seismic waves and send alerts before strong shaking arrives. The aim is to give people a few precious seconds to move to safety, stop trains and protect sensitive equipment.

This time, however, the automatic algorithm greatly overestimated the magnitude. JMA has begun a detailed review of how the system works and how it assessed the data, to establish the cause of the error.