November 13, 2025
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion
* On October 25, an earthquake with magnitude (M) 5.8 occurred offshore southeast of the Nemuro Peninsula and recorded maximum seismic intensity 5 Lower in Nemuro City, Hokkaido.
* On October 22, an M5.1 earthquake occurred offshore of Kushiro at a depth of approximately 45 km. Just a few days later, on October 25, an M5.8 earthquake occurred near its epicenter, offshore southeast of the Nemuro Peninsula, at a depth of approximately 40 km. The focal mechanisms indicate a pressure axis oriented in an NW-SE direction, suggesting that they occurred at the boundary between the Pacific Plate and the continental plate.
GNSS observations indicate that there was no significant crustal deformation associated with the M5.8 earthquake on October 25.
* On October 5, an M6.0 earthquake occurred offshore of Fukushima Prefecture at a depth of approximately 45 km. Just two days later, on October 7, an M5.0 earthquake occurred near the same epicenter at a depth of approximately 50 km. Both events involved reverse faulting, with the pressure axis oriented in a WNW-ESE direction. They occurred at the boundary between the Pacific and continental plates.
* On October 26, an M4.7 earthquake occurred in northern Tochigi Prefecture at a depth of approximately 5 km. It involved strike-slip faulting, with a pressure axis oriented NW-SE. It was an intraplate earthquake.
There was no remarkable activity.
* On October 8, an M5.3 occurred in the ocean near Tokara Islands (near Kodakarajima Island). It involved a strike-slip faulting, with a tension axis oriented in an NNE-SSW direction. Around its epicenter, seismic activity started increasing on June 21, 2025, peaking with the M5.5 earthquake on July 3. By July 7, 8 earthquakes with maximum seismic intensity 5 Lower or greater were recorded. Then, since July 20, both seismic activities and the number of large earthquakes have gradually declined. These events occurred within the continental plate.
GNSS observations recorded horizontal movements in Takarajima, Kodakarajima, and Akusekijima Islands during the recent surge in seismic activity; however, these have since decreased.
Furthermore, in October alone, 37 earthquakes of an M1 or higher were recorded. This seismic activity level (several daily earthquakes of an M1 or greater) suggests that this trend may continue for the time being.
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.
* On November 9 at 17:03, an M6.9 earthquake occurred offshore of Sanriku
at a depth of approximately 15 km. This event occurred at the boundary
between the Pacific Plate and the continental plate and involved reverse
faulting, with the pressure axis oriented in a WNW-ESE direction. The earthquake
also triggered a tsunami that reached a height of 0.2 meters at Kuji Port
and Ofunato in Iwate Prefecture (preliminary report).
Seismic activity around the epicenter started increasing on November 4. By November 11, 25 earthquakes of magnitude 5.0 or greater had occurred, including an M6.1 earthquake on November 9 at 17:14, an M6.6 earthquake on the same day at 17:54, and an M6.4 earthquake on November 10 at 16:23. This intense seismic activity is still ongoing.
This earthquake occurred offshore south of Iwate Prefecture, an area anticipated by the Earthquake Research Committee in its "Long-Term Evaluation of Seismic Activity Along the Japan Trench" published on February 26, 2019. In this region, the probability of a moderate interplate earthquake (approximately magnitude 7.0 to 7.5) occurring within the next 30 years is classified as Rank III (high) (#), placing the region among those with the highest probabilities of trench-type earthquakes. Additionally, its epicentral area is also close to that of the 1896 Meiji Sanriku Earthquake (Tsunami Magnitude 8.6 - 9.0) where the probability of a "trench-adjacent interplate earthquake (tsunami earthquake, etc.)" occurring in the next 30 years is also classified as Rank III (high).
This earthquake occurred in a region prone to a successive occurrence of earthquakes of similar magnitude (this is referred to as "successive occurrence region"). Past examples indicate that when a large earthquake occurs in such areas, it is common for subsequent events of similar or even larger magnitudes to follow. For instance, in late October 1989, several earthquakes with an M6.0 or greater were recorded and culminated with an M7.1 earthquake just four days later. Similarly, in July 1992, an M6.1 earthquake was followed within two days by two M6.9 earthquakes, among a series of M6.0 events or greater. Therefore, it is advisable to exercise caution regarding the possibility of M6.9 earthquakes or greater for approximately one week following the initial event.
#: Rank of the probability of occurrence of a subduction zone earthquake within 30 years is expressed as follows: rank III: greater than 26%, rank II: 3% ~26%, rank I: smaller than 3%, rank X: unknown (an immediate occurrence of an earthquake cannot be denied).
Note: GNSS is a general name of a satellite positioning system such as GPS.
November 13, 2025
Earthquake Research Committee
The numbers of earthquakes by magnitude (M) in and around Japan in October 2025 are as follows.
(Reference)
The following events for the period from October 2024 until the end of September 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 | ||
# 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
6 earthquakes with seismic intensity 1 or greater were recorded in October,
suggesting that seismic activity is still ongoing.
GNSS observations indicate that crustal deformation, including horizontal deformation exceeding 2 cm over a 22-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.
– GNSS observations indicate that crustal deformation in the southern Kii Peninsula has deviated from previous trends. This change was first observed in early 2020, with a temporary stall occurring around autumn 2024. The deformations were then observed again in early 2025. After a thorough examination, it was confirmed that the deformation had ceased following the stall in autumn 2024..
– GNSS observations indicated that afterslip from crustal deformation was recorded at the Miyazaki observation point for approximately nine months following the M6.6 earthquake under the Hyuganada Sea on January 13, 2025, including a horizontal shift of about 4 cm in the southeast direction.
– Since July, there has been a notable increase in seismic activity in the ocean near Tokara Islands (near Suwanosejima Island). By the end of October, a total of 199 earthquakes with maximum seismic intensity 1 or greater were recorded (14 events in October: 5 with maximum seismic intensity 2). The largest event in October was an M3.4 earthquake (maximum seismic intensity 2). This seismic activity is thought to be related to volcanic activity on Suwanosejima Island.
– "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 November
10 (reference below).)
(Reference)
Recent Crustal Activity Around the Nankai Trough (Seismological and Volcanological Department, Japan Meteorological Agency, November 10, 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: