TOKYO, Oct 09 (News On Japan) - A tsunami advisory was temporarily issued for a wide area along Japan's Pacific coast on Monday morning, despite no earthquakes with a seismic intensity of 1 or higher being observed.
Experts suggest that the possibility of an "underwater landslide" may have caused the tsunami.
Between around 6 AM and 8 AM, a tsunami was observed in the Izu Islands and along the coast of Chiba Prefecture. The tsunami warning was in effect until around noon.
The tsunami is believed to have been caused by an earthquake near Torishima. However, the scale of that earthquake is unknown, and no seismic intensity of 1 or higher was observed during this time.
Normally, tsunami warnings are issued based on identifying the earthquake's epicenter, depth, and magnitude.
Earthquakes of magnitude 6 have been occurring frequently in this area since last week.