August 12, 2026
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion

Evaluation of Seismic Activities for July 2026

1 Major Seismic Activities

* On July 28, an earthquake with a magnitude (M) of 7.1^(#1) occurred in the Kumamoto region, Kumamoto Prefecture. The quake recorded a maximum seismic intensity 7 in Kumamoto Prefecture, causing deaths and damage. Moreover, a long-period ground motion of class 4 was also recorded in Kumamoto Prefecture.

• Seismic Activity Across Japan in July 2026 (Magnitude 4.0 or Greater)

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2 Seismic Activities by Region

(1) Hokkaido Region

There was no remarkable activity.

• Hokkaido Region

to supplementary reports

(2) Tohoku Region

* On July 1 and 14, earthquakes with M6.1 and M5.0, respectively, occurred offshore of Iwate Prefecture, at a depth of approximately 40 km. Their focal mechanisms indicated a pressure axis oriented in an E-W direction. These events occurred at the boundary between the Pacific and the continental plates.
Since the M7.2 earthquake on June 25, there has been ongoing seismic activity around the epicenter regions, with 17 earthquakes of seismic intensity 1 or greater recorded in July.
To the southeast of this seismic activity zone lies the seismic activity of the earthquakes offshore Sanriku on November 9, 2025 (M6.9) and April 20, 2026 (M7.7). To the east of these series of seismic activity zones, tremor activity has continued intermittently since the earthquake offshore of Sanriku on November 4, 2025 (M5.3).
GNSS observations indicate that approximately 3 months after the earthquake offshore of Sanriku on April 20 (M7.7), horizontal displacements, due to post-seismic deformations, were primarily recorded in Iwate Prefecture. For instance, Kuji station, a deformation of around 7cm in the east-southeast direction. The afterslip, inferred from these post-seismic deformations, is believed to continue in the seismic activity zone of the earthquake offshore of Sanriku on April 20 (M7.7), and to the west and east of this seismic activity zone. Moreover, the analysis of repeating earthquakes indicates the ongoing occurrence of aseismic slip events in these regions.
Since 25 June, seismic activity has continued near the epicenter of the largest aftershock (M7.2 on January 7, 1995) on the western edge of the "1994 Sanriku-haruka-oki Earthquake" (M7.6) source region, including this earthquake. Moreover, this seismic activity, along with the series of seismic activity zones from offshore of Sanriku to offshore of Iwate Prefecture since November 2025, the focal area of the "1994 Sanriku-haruka-oki Earthquake," and the seismic activity zone of the earthquake offshore east of Aomori Prefecture (M7.5 on December 8, 2025), are located respectively in the southern, central, and northern parts of the focal area of the "1968 Tokachi-oki Earthquake" (M7.9).
The M7.2 earthquake on June 25 occurred in the area anticipated by the Earthquake Research Committee as likely to experience "slightly smaller interplate earthquakes" (approximately M7.0 to M7.5) in its "Long-Term Evaluation of Seismic Activity Along the Japan Trench" (published February 26, 2019) for "offshore east of Aomori Prefecture and offshore north of Iwate Prefecture regions." The probability of such an earthquake occurring within 30 years is classified as Rank III (high probability)(#). This represents the highest probability among subduction-zone earthquakes. Note that the "1994 Sanriku-haruka-oki Earthquake," which occurred in the same area, is categorized as a "slightly smaller interplate earthquake" of "offshore east of Aomori Prefecture and offshore north of Iwate Prefecture regions", whereas the 1968 Tokachi-oki Earthquake, also in the same area, is considered as a "large interplate earthquake" (approximately M7.9). Both have a 30-year occurrence probability classified as Rank III (high).

• Tohoku Region
• Earthquakes Offshore of Iwate Prefecture on July 1 and 14 (Seismic Activity From Offshore Sanriku to Offshore of Iwate Prefecture Since November 2025)
• Earthquakes Offshore of Iwate Prefecture on July 1 and 14 (Seismic Activity From Offshore Sanriku to Offshore of Iwate Prefecture Since November 2025) (continued)
• Tremor Activity in the Northern Japan Trench in July 2026
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• GNSS Observation Data After the Earthquake Offshore of Sanriku (April 20, M7.7) (provisional) (continued)
• Slow Slip in the Tohoku Region Estimated from GNSS Data (provisional)
• The Progression of Aseismic Slip Estimated from Repeating Earthquakes
• Comparison of Seismic Activity Zones from Offshore East of Aomori Prefecture to Offshore of Sanriku
• Target Areas for Long-Term Evaluation and the Current Earthquake
• Probability of an Earthquake Occurring Within the Next 30 Years (As of January 1, 2026)

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(3) Kanto-Chubu Region

There was no remarkable activity.

• Kanto - Chubu Region

to supplementary reports

(4) Kinki-Chugoku-Shikoku Region

There was no remarkable activity.

• Kinki-Chugoku-Shikoku Region

to supplementary reports

(5) Kyushu-Okinawa Region

* On July 1, an M5.1 earthquake occurred in the northern plains of Miyazaki Prefecture, at a depth of approximately 15 km. Its focal mechanism was a strike-slip fault type with a tension axis oriented in an NNW-SSE direction. It occurred within the Earth's crust.

* On July 3, an M6.5 earthquake occurred offshore northwest of Miyakojima Island at a depth of approximately 15 km (according to CMT solutions). Its focal mechanism was a strike-slip fault type with a tension axis oriented in an NW-SE direction. It occurred within a continental plate.

* On July 17, an M5.2 earthquake occurred offshore east of the Osumi Peninsula. Its focal mechanism was a strike-slip fault type with a pressure axis oriented in an NW-SE direction.

* For the information about the M7.1 earthquake in the Kumamoto region, Kumamoto Prefecture on June 28, please refer to "Evaluation of the 2026 Kumamoto Earthquake."

• Kyushu Region
• Earthquake in the Northern Plains of Miyazaki Prefecture on July 1
• Earthquake Offshore East of the Osumi Peninsula on July 17
• Okinawa Region
• Earthquake Offshore Northwest of Miyakojima Island on July 3 (Earthquake at Approximately 100 km West of Kumejima Island)

to supplementary reports

(6) Around the Nankai Trough

There have been no abnormal changes that would suggest that the likelihood of a great earthquake occurring along the Nankai Trough has increased compared to the normal background level of activity.

• Vertical Movement of GNSS-Based Control Stations - Omaezaki
• Vertical Movements of GNSS-Based Control Stations - the Kii Peninsula and Around Cape Muroto -

to supplementary reports

(7) Other Regions

* On July 3, an M6.0 earthquake occurred in the northwestern Pacific.

• Earthquake in the Northwest Pacific on July 3

#1: The Japan Meteorological Agency has designated the magnitude 7.1 earthquake that occurred in the Kumamoto region, Kumamoto Prefecture on July 28, 2026, along with the subsequent series of seismic events, as the "2026 Kumamoto Earthquake."

Note: GNSS refers to a generic term for satellite positioning systems, including GPS.

Supplementary Information to the Evaluation of Seismic Activities for July 2026

August 12, 2026
Earthquake Research Committee

1 Major Seismic Activities

The numbers of earthquakes by magnitude (M) in and around Japan in July 2026 are as follows.

• M4.0 or over: 128 (98 events in June)
• M5.0 or over: 17 (13 events in June)
• M6.0 or over: 5 (3 events in June)

Of the above monthly occurrences, the 2026 Kumamoto Earthquake recorded 30 events with M4.0 or greater, 4 events with M5.0 or greater, and 2 events with M6.0 or greater.

(Reference)

• M4.0 or over: 81 / month (69-104)
• (Median monthly number from 1998 to 2017, half of the numbers are included in the interval shown in parentheses)
• M5.0 or greater: 10 / month (7-14)
• (Median monthly number from 1973 to 2017, half of the numbers are included in the interval shown in parentheses)
• M6.0 or greater: 1 / month (0-2)
• (Median monthly number from 1919 to 2017, half of the numbers are included in the interval shown in parentheses)
• M6.0 or greater: 16 / year (12-21)
• (Median annual number from 1919 to 2017, half of the numbers are included in the interval shown in parentheses)

The following events for the period from July 2025 until the end of June 2026 have been listed as "Major Seismic Activities" in the monthly "Evaluation of Seismic Activities."

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2 Nationwide Seismic Activities by Region

(1) Hokkaido Region

There is no supplementary information for Hokkaido region.

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(2) Tohoku Region

There is no supplementary information for Tohoku region.

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(3) Kanto-Chubu Region

– GNSS observations suggest that crustal deformation in the area stretching from western Shizuoka to eastern Aichi Prefectures differs from the normal trend, a phenomenon that has been observed since early 2022. It is believed that this change is the result of 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 towards the eastern side of Lake Hamana.

• Coordinate Time Series (Black Circles) and Calculated Values (Red Lines) of Observing Stations in the Tokai Region
• Long-Term Slow Slip in Tokai Region Estimated from GNSS Data (provisional)

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(4) Kinki-Chugoku-Shikoku Region

– Since February 2025, there have been continuous clusters of tremors occurring at depths of approximately 25 to 30 km in the lower crust of northern Yamaguchi Prefecture. These series of tremors have been accompanied by slight crustal deformations. Moreover, since around mid-2025, there have been continuous clusters of tremors occurring at depths of approximately 5 to 20 km within the crust of northern Yamaguchi Prefecture.

– Since July 29, deep low-frequency earthquakes (tremors) were recorded near the boundary between the Philippine Sea Plate and the continental plate in western Shikoku. Strain and tilt data suggest that the slight crustal deformations recorded in the area were almost synchronized with the deep low-frequency earthquakes (tremors). It is believed that this phenomenon resulted from a short-term slow slip event occurring deep within the boundary between the two plates.

• Deep Low-Frequency Earthquake (Tremor) Activity and Short-Term Slow Slip in Central and Western Shikoku
• Short-Term Slow Slip Recorded from Central to Western Shikoku (Since July 19)
• Short-Term Slow Slip Recorded from Central to Western Shikoku (Since July 19) (continued)
• Short-Term Slow Slip Recorded from Central to Western Shikoku (Since July 19) (continued)
• Status of Deep Low-Frequency Tremors Activity in Shikoku (July 2026)
• Short-Term SSE Analysis Results for Shikoku (July 2026)
• Short-Term SSE Analysis Results for Shikoku (July 2026) (continued)
• Seismic Activity and Crustal Deformation
• Crustal Deformation Around Seismic Activity Zone in Northern Yamaguchi Prefecture (provisional)
• Crustal Deformation Around Seismic Activity Zone in Northern Yamaguchi Prefecture (provisional) (continued)
• Crustal Deformation Around Seismic Activity Zone in Northern Yamaguchi Prefecture (provisional) (continued)
• Crustal Deformation Around Seismic Activity Zone in Northern Yamaguchi Prefecture (provisional) (continued)
• Crustal Deformation Around Seismic Activity Zone in Northern Yamaguchi Prefecture (provisional) (continued)
• Crustal Deformation Around Seismic Activity Zone in Northern Yamaguchi Prefecture (provisional) (continued)
• Non-Stationary Crustal Deformation in Northern Yamaguchi Prefecture Based on Integrated GNSS Analysis
• Non-Stationary Crustal Deformation in Northern Yamaguchi Prefecture Based on Integrated GNSS Analysis (continued)

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(5) Kyushu-Okinawa Region

There is no supplementary information for the Kyushu-Okinawa region.

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(6) Around the Nankai Trough

– "There have been no abnormal changes that would suggest that the likelihood of a great earthquake occurring along the Nankai Trough has increased compared to the normal background level of activity.":
(This evaluation corroborates with the views presented at the regular meeting of the Nankai Trough Earthquake Assessment Committee on August 7 (reference below).)

(Reference)

Recent Crustal Activity Around the Nankai Trough (Seismological and Volcanological Department, Japan Meteorological Agency, August 7, 2026)
"Currently, there have been no abnormal changes that would suggest that the likelihood of a great earthquake occurring along the Nankai Trough has increased compared to the normal background level of activity. (Excerpted)"

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