A series of earthquakes has rattled Japan’s Tokara Islands, located between Kyushu and the Ryukyu archipelago, sparking fears of a potential major quake. According to Japan’s Meteorological Agency, over 250 felt earthquakes were recorded from 6am on 21 June until midday on 23 June. Although none of the quakes exceeded magnitude 4, the continuous shaking has left residents anxious and unable to sleep, worried that the “Tokara pattern” of frequent quakes foreshadows a larger disaster.
Experts noted that the largest quake occurred around 12:15am on 23 June near Akuseki Island, registering magnitude 3.6 with a seismic intensity of level 4. Smaller tremors continued relentlessly, with a total of 252 quakes of intensity 1 or above logged in just three days. This includes three intensity-4 quakes, 15 at level 3, two at level 2, and 172 at level 1.
Despite the intense activity, local authorities in Akuseki Island reported no injuries or property damage so far. However, the constant tremors have deeply affected the mental well-being of residents, many of whom reported severe sleep deprivation and mounting concerns about a possible larger quake.
Experts Warn of Potential for Stronger Earthquakes
The Fukuoka Meteorological Observatory explained that historically, the Tokara Islands are prone to periods of swarm earthquakes, and the current situation is not unprecedented. Similar swarms occurred as recently as September 2023, when the region recorded 346 earthquakes of intensity 1 or above in a single month. Another swarm happened in December 2021, with 308 quakes, including one of magnitude 5.9 that caused landslides.
Given this historical context, the observatory emphasised that while such swarms can be a natural release of seismic energy, there remains a risk of a stronger earthquake striking the region. Authorities urged residents to stay vigilant and review their earthquake preparedness plans, especially as Japan is located in one of the world’s most seismically active zones.
History of “Tokara Pattern” Sparks Public Anxiety
The notion of a “Tokara pattern” comes from previous incidents where earthquake swarms in the Tokara Islands were followed by major quakes elsewhere in Japan. Past records show that in 2000, a series of 37 quakes in the Tokara area preceded a magnitude 7.3 earthquake in Tottori; in 2003, a smaller swarm was followed by a magnitude 7.1 quake in Tokachi; and in early 2011, increased activity in Tokara occurred shortly before the devastating magnitude 9.0 Tōhoku earthquake.
Seismologist Professor Shigeru Nakao of Kagoshima University, however, cautioned against drawing definitive conclusions. He highlighted that while the timing of swarms and larger quakes can appear linked, there is no proven causal relationship. He stressed that Japan’s entire archipelago is earthquake-prone, and such patterns could be coincidental.
Residents Urged to Stay Prepared for Emergencies
Japan’s Meteorological Agency concluded by stating that the ongoing seismic activity may persist for some time. They advised residents of the Tokara Islands and surrounding regions to remain alert for stronger tremors, secure furniture, prepare emergency kits, and confirm evacuation routes.
This seismic episode serves as a stark reminder of the importance of disaster preparedness in earthquake-prone countries like Japan, especially given the unpredictability of seismic events and their potential to cause widespread destruction.