July 9, 2025
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion
On June 30, a magnitude (M) 5.3 earthquake occurred in the ocean near Tokara Islands. The earthquake recorded a maximum seismic intensity 5 Lower in Toshima Village, Kagoshima Prefecture.
* On June 2 and 3, M6.1 and M5.2 earthquakes occurred offshore of Tokachi at depths of approximately 25 km and 35 km, respectively. These events occurred at the plate boundary between the Pacific and continental plates and featured a reverse faulting focal mechanism with a pressure axis in the WNW-ESE direction.
GNSS observations indicate that these events caused slight crustal deformation around Cape Erimo.
* On June 19 and 22, M6.0 earthquakes occurred offshore southeast of the Nemuro Peninsula at a depth of approximately 25 km. These events occurred at the plate boundary between the Pacific and continental plates and featured a reverse faulting focal mechanism with a pressure axis in the NW-SE direction.
There was no remarkable activity.
* On June 25, an M4.2 earthquake occurred offshore of Ibaraki Prefecture at a depth of approximately 55 km. It occurred at the plate boundary between the Pacific and continental plates and featured a reverse faulting focal mechanism with a pressure axis in the WNW-ESE direction.
There was no remarkable activity.
* For information on seismic activity that has occurred in the ocean near Tokara Islands since June 21, please refer to the "Evaluation of Seismic Activity in the Ocean Near Tokara Islands."
* There has been observed no unusual change which indicates that the possibility of occurrence of a great earthquake along the Nankai Trough has relatively risen compared to the normal time.
* On June 11, an M6.0 earthquake occurred at a depth of approximately 40 km near Taiwan. Its focal mechanism involved a reverse fault with a pressure axis in the WNW-ESE direction.
* On June 14, an M6.2 earthquake occurred in the Kuril Islands.
Note: GNSS is a general name of a satellite positioning system such as GPS.
July 9, 2025
Earthquake Research Committee
The numbers of earthquakes by magnitude (M) in and around Japan in June 2025 are as follows.
Of the above monthly totals, the number of earthquakes in the ocean near Tokara Islands was 41, 6, and 0 for M4.0 or greater, M5.0 or greater, and M6.0 or greater, respectively.
(Reference)
The following events for the period from June 2024 until the end of May 2025 have been listed as "Major Seismic Activities" in the monthly "Evaluation of Seismic Activities."
| – In the Noto Region, Ishikawa Prefecture# | M6.0 on June 3, 2024 (Depth of approximately 15 km) |
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| – Under the Hyuganada Sea | M7.1 on August 8, 2024 (Depth of approximately 30 km) |
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| – In western Kanagawa Prefecture | M5.3 on August 9, 2024 (Depth of approximately 15 km) |
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| – In the northern Ibaraki Prefecture | M5.1 on August 19, 2024 (Depth of approximately 10 km) |
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| – In the Ocean Area near Torishima Island | M5.8 on September 24 (Depth of approximately 10 km) |
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| – Offshore west of Ishikawa Prefecture# | M6.6 on November 26, 2024 (Depth of approximately 10 km) |
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| – Under the Hyuganada Sea | M6.6 on January 13, 2025 (Depth of approximately 35 km) |
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| – In Aizu, Fukushima Prefecture | M5.2 on January 23, 2025 (Depth of approximately 5 km) |
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| – In northern Nagano Prefecture | M5.1 on April 18, 2025 (Depth of approximately 15 km) |
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# Seismic activity of the 2024 Noto Peninsula Earthquakes
There is no supplementary information for Hokkaido region.
There is no supplementary information for Tohoku region.
– In the Noto region, Ishikawa Prefecture, seismic activity has been occurring since December 2020. It began with relatively small earthquakes, followed by an M5.4 earthquake in June 2022, an M6.5 in May 2023, an M7.6 in January 2024, and an M6.0 in June 2024. Although seismic activity in the activity zone of the M7.6 earthquake has been decreasing, there were still 7 earthquakes of seismic intensity 1 or greater recorded in June.
GNSS observations indicate that crustal deformation, including horizontal deformation exceeding 1 cm over a 18-month period, was still detected in a broad area centered on the Noto Peninsula and extending into Toyama, Niigata, and Nagano prefectures following the M7.6 earthquake. This deformation is believed to be an after-slip effect.
In the Sea of Japan, there have been cases of M6.0 earthquakes occurring several years after large earthquakes. Notable examples include the earthquakes that followed the 1964 Niigata Earthquake (M7.5), the 1983 Central Sea of Japan Earthquake (M7.7), and the 1993 offshore southwest of Hokkaido (M7.8) Earthquake. Additionally, there have been earthquakes with M6.0 or greater, including the Noto Hanto Earthquake in 2007 (M6.9), which occurred before the series of seismic activities that began in December 2020 in the Noto Peninsula region.
– According to the GNSS observation, the crustal deformation different from the ordinary trend in the area extending from the western Shizuoka to the eastern Aichi Prefectures has been observed since early 2022. This phenomenon is considered to be caused by a long-term slow slip around the Atsumi Peninsula at the deeper part of the boundary between the Philippine Sea and the continental plates.
– According to the GNSS observation, the crustal deformation different from the ordinary trend in the central Shikoku has been observed since about spring 2019. This phenomenon is considered to be caused by a long-term slow slip around the central Shikoku at the deeper part of the boundary between the Philippine Sea plate and the continental plate. This crustal deformation was temporally decaying since the fall of 2023 and appeared to continue from the spring of 2024 but slowed again in the fall of 2024.
– According to GNSS observations, crustal deformation different from the previous trend has been observed in the southern Kii Peninsula since the beginning of 2020. This seems to be caused by long-term slow slip at the deep boundary between the Philippine Sea Plate and the continental plate around the southern Kii Peninsula. This deformation has been stagnant since the fall of 2024.
– The cluster tremors in northern Yamaguchi Prefecture that started in February 2025 have been declining since June. GNSS observations indicate that this activity caused slight crustal deformation in the seismic activity area.
– Deep low-frequency earthquakes (tremors) have been occurring since June 7 near the boundary between the Philippine Sea Plate and the continental plate, stretching from western to central Shikoku. GNSS observations and tilt data indicate that the recorded slight crustal deformation was nearly synchronized with these tremors. This activity is thought to be linked to short-term slow slip in the deep part of the boundary between the Philippine Sea Plate and the continental plate.
– According to GNSS observations, crustal deformation, considered to be post-seismic deformation, was observed mainly in the southern part of Miyazaki Prefecture for about five months (until the M6.6 earthquake on January 13, 2025) following the M7.1 earthquake under the Hyuganada Sea on August 8, 2024, including a horizontal displacement of about 5 cm to the southeast at the Miyazaki observatory. In addition, after the M6.6 earthquake, crustal deformations, considered post-seismic deformation, were also observed, including horizontal displacement of about 3 cm in the southeast direction at the Miyazaki station for about five months.
– "There has been observed no unusual change which indicates that the possibility of occurrence of a great earthquake along the Nankai Trough has relatively risen compared to the normal time.":
(This evaluation is in agreement with the views presented at the regular meeting of the Nankai Trough Earthquake Assessment Committee on July 7 (reference below).)
(Reference)
Recent Crustal Activity Around the Nankai Trough (Seismological and Volcanological Department, Japan Meteorological Agency, July 7, 2025)
"In the present, there has been observed no unusual change which indicates that the possibility of occurrence of great earthquakes along the Nankai Trough has relatively risen compared to the normal time. (Excerpted)"
Reference 1
Earthquakes that are described in the "Evaluation of Seismic Activity" (Monthly Report of Seismic Activity in Japan) have the following features.
Reference 2
Information that is described in the "Supplementary Information to the Evaluation" includes: