Tsunami warning 10pm August 31

That last siren you heard was a tsunami warning for a 50cm tsunami. Apparently the warning period with begin from around 11:30pm. The tsunami appears to be as a result of a magnitude 7.9 earthquake off the coast of the Philippines. According to the JMA website the Tsunami warning is set to ‘advisory’.

http://www.jma.go.jp/en/tsunami/