Japan's Ibaraki Prefecture and Tokyo shaken by magnitude 5.9 earthquake

Tokyo, Japan – A powerful earthquake jolted the Kanto region of Japan early on July 23, with strong tremors felt as far as Tokyo. The Japan Meteorological Agency (JMA) reported a magnitude 5.9 earthquake originating in southern Ibaraki Prefecture, approximately 70 kilometers deep, causing significant shaking but no tsunami.

The earthquake, which occurred around 2 a.m., triggered the JMA's "urgent earthquake report" system, sending alerts and loud alarms to mobile phones across the affected areas. Residents in Tokyo and surrounding prefectures like Saitama and Chiba experienced intense shaking, with seismic intensity reaching 5-lower in several locations. This level of shaking is described as causing widespread fear, with dishes falling from shelves and books tumbling from bookshelves.

For Tokyo's 23 central wards, this was the first time experiencing tremors of intensity 5-lower or higher since a magnitude 5.9 earthquake on October 7, 2021. The intensity 5-lower classification indicates that most people would feel fear, and unsecured objects could fall. Outdoors, ground cracks could form, and landslides could be triggered.

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Prepare for strong shaking due to an earthquake in Ibaraki Prefecture.

Adding to the concern, a "long-period ground motion" of Level 2 was observed in Tokyo's 23 wards, Saitama, and Chiba. Long-period ground motion refers to seismic waves that are longer and slower, posing a greater threat, especially to tall buildings. Level 2 indicates that occupants of high-rise buildings would feel strong swaying, making it difficult to walk without holding onto something.

Experts noted that southern Ibaraki Prefecture is a seismically active area. Professor Shinichi Sakai of the University of Tokyo's Earthquake Research Institute suggested that the relatively deep hypocenter allowed the strong tremors to propagate over a wide area. The JMA has warned residents to be cautious of aftershocks, with the possibility of tremors up to intensity 5-lower over the next week.

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Ibaraki Prefecture's southern region is an area where earthquakes occur frequently. The hypocenter was relatively deep, so strong tremors were transmitted over a wide area.