December 25, 2025
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion
* On November 9, a magnitude (M) 6.9 earthquake occurred offshore of Sanriku, and triggered a tsunami that reached heights of 16 cm in Ofunato and 9 cm in Miyako, both located in Iwate Prefecture (provisional values).
* On November 25, an M5.8 earthquake occurred in the Aso region in Kumamoto Prefecture at a depth of approximately 10 km. The quake registered a maximum seismic intensity 5 Upper in Kumamoto Prefecture, resulting in injuries and other damage.
There was no remarkable activity.
* At 17:03 on November 9, an M6.9 earthquake occurred offshore of Sanriku at a depth of approximately 15 km. The focal mechanism involved reverse faulting, with the pressure axis oriented in the WNW-ESE direction, and occurred at the boundary between the continental and Pacific Plates. This event triggered a tsunami that reached heights of 16 cm in Ofunato and 9 cm in Miyako, both located in Iwate Prefecture (provisional values).
Following the M5.3 earthquake on November 4, tremor activity was detected near the event's focal area with a sharp increase in seismic activity. From November 8, the seismic activity started expanding in all directions. The observed tremor activity and the expansion of seismic activity suggest that slow slip may have occurred in this region before and after the M6.9 event.
Although the number of earthquakes has decreased compared to immediately after the M6.9 quake, seismic activity persists, with 50 events of maximum seismic intensity 1 or greater recorded by December 22. Additionally, tremor activity has sharply increased since the M6.9 quake and continues intermittently up to now.
GNSS observations and strainmeter data revealed that the earthquake caused minor crustal deformation. Additionally, slight crustal deformation, thought to be induced by postseismic activity, was observed but has since diminished.
This earthquake occurred in the area (offshore south of Iwate Prefecture) anticipated by the Earthquake Research Committee in its "Long-Term Evaluation of Seismic Activity Along the Japan Trench" (published February 26, 2019). The probability of "slightly smaller interplate earthquakes" (approximately M7.0 to M7.5) occurring within the next 30 years is classified as Rank III (high probability) (#). In addition, its epicenter is adjacent to that of the 1896 Meiji Sanriku earthquake (tsunami magnitude 8.6-9.0), and the probability of an "interplate earthquake near the trench (tsunami earthquake, etc.)" occurring within the next 30 years is also classified as rank III (high).
There was no remarkable activity.
There was no remarkable activity.
* On November 3, an M3.3 earthquake occurred at a very shallow depth in the Satsuma region, Kagoshima Prefecture. Seismic activity in the earthquake's focal area temporarily increased on November 3, and throughout November, a total of 17 events with seismic intensity 1 or greater were recorded. These earthquakes occurred within the crust.
* On November 25, an M5.8 earthquake occurred in the Aso region, Kumamoto Prefecture at a depth of approximately 10 km. The earthquake occurred within the crust, and its focal mechanism involved strike-slip faulting with a tension axis oriented N-S direction.
GNSS observations revealed that the earthquake caused slight crustal deformation.
This event took place within the activity area of the "2016 Kumamoto
Earthquakes," which occurred in April 2016.
* 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.
* For the M7.5 earthquake that occurred on December 8 offshore east of Aomori Prefecture, please refer to "Evaluation of Earthquake Offshore East of Aomori Prefecture on December 8, 2025."
#: The probability of a subduction-zone earthquake occurring within the next 30 years is ranked as follows: Rank III: greater than 26%, Rank II: 3% ~ 26%, Rank I: less than 3%, Rank X: unknown (an immediate earthquake cannot be ruled out).
Note: GNSS is a general name of a satellite positioning system such as GPS.
December 25, 2025
Earthquake Research Committee
The numbers of earthquakes by magnitude (M) in and around Japan in November 2025 are as follows.
(Reference)
The following events for the period from November 2024 until the end of October 2025 have been listed as "Major Seismic Activities" in the monthly "Evaluation of Seismic Activities."
| – 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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| – In the ocean near Tokara Islands | M5.3 on June 30, 2025 | ||
| – In the ocean near Tokara Islands | M5.1 on July 2, 2025 | ||
| – In the ocean near Tokara Islands | M5.6 on July 2, 2025 | ||
| – In the ocean near Tokara Islands | M5.5 on July 3, 2025 (Depth of approximately 10 km) |
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| – In the ocean near Tokara Islands | M5.4 on July 5, 2025 | ||
| – In the ocean near Tokara Islands | M4.9 on July 6, 2025 | ||
| – In the ocean near Tokara Islands | M5.5 on July 6, 2025 | ||
| – In the ocean near Tokara Islands | M5.1 on July 7, 2025 | ||
| – Offshore east of the Kamchatka Peninsula, Russia | M8.8 on July30, 2025 | ||
| – In the ocean near Tokara Islands | M4.7 on September 17, 2025 | ||
| – Offshore southeast of the Nemuro Peninsula | M5.8 on October 25, 2025 (Depth of approximately 40 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.
– Seismic activity in the Noto region, Ishikawa Prefecture has been
on the rise since December 2020. Initially, only relatively small earthquakes
were recorded; however, this changed with the occurrence of several large
events, including an M6.5 earthquake in May 2023, an M7.6 earthquake in
January 2024, and an M6.6 earthquake in November 2024. In the activity
area of the M7.6 earthquake, seismic activity has been decreasing, yet
3 earthquakes with seismic intensity 1 or greater were recorded in November,
suggesting that seismic activity is still ongoing.
GNSS observations indicate that crustal deformation, including horizontal deformation exceeding 2 cm over a 23-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.
Along the Sea of Japan, earthquakes with an M6.0 or greater have been recorded several years after major seismic events, such as the 1983 Sea of Japan earthquake (M7.7). Moreover, the Noto Peninsula has experienced large, damaging earthquakes of magnitude M6.0 or greater, including the Noto Hanto Earthquake in 2007 (M6.9), which occurred prior to the current series of seismic activities that began in December 2020.
– 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 change is believed to result from long-term slow slip occurring deep within the boundary between the Philippine Sea Plate and the continental plate extending from the Atsumi Peninsula to Lake Hamana. The slip center is gradually shifting from the Atsumi Peninsula toward Lake Hamana.
– Between November 9 and 16, deep low-frequency earthquakes (tremors), were detected in the northern Kii Peninsula, near the boundary between the Philippine Sea Plate and the continental plate. The strain and tilt data indicate that the slight crustal deformations observed in the area were almost synchronized with the deep low-frequency seismic activity. This phenomenon is believed to result from a short-term slow slip occurring at the deep boundary between the Philippine Sea Plate and the continental plate.
– GNSS observations indicate that the gradual deformations following the earthquakes under Hyuganada Sea on August 8, 2024, and January 13, 2025, are postseismic deformations linked to these events; however, the magnitude of these deformations has become very small.
– Seismic activity surged in the ocean near Tokara Islands (near
Kodakarajima Island) starting on June 21, 2025. By July 7, a total of 8
earthquakes with maximum seismic intensity 5 Lower or greater were recorded,
including an M5.5 earthquake on July 3. Since July 20, both seismic activity
and the number of large earthquakes have decreased. However, in November,
12 earthquakes with seismic intensity 1 or greater were recorded, with
the largest being an M3.3 event on November 7. These seismic events occurred
within the continental plate.
GNSS observations recorded horizontal deformations on Takarajima, Kodakarajima, and Akusekijima Islands during the recent surge in seismic activity; however, these have since decreased.
Additionally, the area around this seismic activity zone has previously experienced extended periods of seismicity lasting several months. For example, during the 2021 activity, seismicity began in April and continued for several months before declining. After a few more months, it became active again in December.
– "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 December
5 (reference below).)
(Reference)
Recent Crustal Activity Around the Nankai Trough (Seismological and Volcanological Department, Japan Meteorological Agency, December 5, 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: