Brief report of the 2024 Noto Peninsula Earthquake in JAPANIAEG Japan National Group (Japan Society of Engineering Geology)
The 2024 Noto Peninsula Earthquake occurred on January 1st in 2024 with a maximum intensity of7, in the northwestern part of Japan. The earthquake caused a magnitude 7.6 at the depth of about
15 km in the Noto region of Ishikawa Prefecture. The seismic mechanism of this earthquake was areverse fault type with a pressure axis in the northwest-southeast direction, and the earthquake
occurred within the earth's crust.
Figure 1 shows the general view of Japan. The Japanese Archipelago is comprised of five island arcs
as shown in the figure. The Philippine Sea Plate has been moving to NW direction 4 cm/yr. on averageand subducting in the Nankai Trough. On the other hand, the Pacific Plate has been moving to WNW
direction 9 cm/yr. on average and subducting in the Japan Trench and the Izu-Ogasawara Trench.
Moreover, the Izu-Ogasawara Island Arc have collided with Honshu Arcs and intruded to northdirection. These continuing movements on the subduction zones at the boundary of the plates are themain causes of large earthquakes and tsunamis. And many active faults are distributed in the island
arcs.

Japan Sea BasinJapan Trench
NotoPeninsula
Pacific Plate

Nankai TroughIzu-Ogasawara
Island Arc

Izu-Ogasawara
TrenchPhilippine Sea Plate

Ryukyu Trench

Fig.1. General topographic view around Japan

0500kmVolcanic front

Nankai TroughSouthwest

year

Southwest JapanWest
Hukuoka

Osaka

East

SagamiTrough East

NagoyaTokyo

Japan Sea

Northeast Japan
SouthNorth

Japan Trench

Sendai

Hokkaido

Chishima Trench

SapporoNoto2000
Comparatively calm period

Comparatively calm period

1900

Comparatively calm period

1800

Hokkaido

Magnitude
9Mt.Fuji Eruption
1700

87Fig.2. Distribution of the historical earthquake in recent 300 years

NotoFigure 2 represents distribution of the historical earthquake in recent 300 years in Japan. Huge
plate boundary earthquakes have sometimes occurred between Philippine Sea plate, Pacific Oceanplate, North American plate, and Eurasian plate respectively around Japan island Arc. Nankai
trough is existed between Philippine Sea plate and Eurasian plate in the Pacific Ocean of west Japanisland south. It is known that huge historical Nankai Earthquake in this trough have occurred in 100
years to 150 years interval and inland earthquake activity mainly in western Japan island haveincreased toward the occurrence of this plate boundary earthquake. After the Hanshin earthquake
which occurred in 1995, activity of earthquakes looks like to increase gradually in all Japan island.
It is not obvious that this time Noto Peninsula earthquake concerns with such increasing of activity
and possibility of nearing Nankai Earthquake occurrence.

Fig. 3. Past seismic activity around Noto Peninsula. The size of circles indicates the magnitude ofearthquakes. This figure is edited to "The 2024 Noto Peninsula Earthquakes" Past Activity,
Comparison with the Topographical Map posted on the website of The Headquarters forEarthquake Research Promotion: https://www.jishin.go.jp/main/chousa/24jan_noto_2/index-e.htm

In the Noto Peninsula area, there have been earthquakes of magnitude > 6.0 in the past, including
a magnitude 6.6 earthquake off the northeast coast on February 7, 1993, and a magnitude 6.9

earthquake off the southwest coast on March 25, 2007 as shown in Figure 3. In recent years, seismicactivity had just increased from December 2020, increased from around May 2023, and then once
seismic activity had returned to its post-December 2020 state. From December 1, 2020 to December
31, 2023, there were 506 earthquakes with intensity ≧ 1, of which 67 earthquakes with intensity >3 occurred. The seismic activity was mainly centered in the northeastern and northern areas of theNoto Peninsula. The seismically active area since January 1, 2024 has traversed the northern part of
the Noto Peninsula in a northeast-southwest direction.

Fig. 4. Coastal Uplift Survey for the2024

NotoPeninsulaEarthquake(edited to the figures posted on thewebsite of Geological Survey of Japan:
https://www.gsj.jp/hazards/earthquake/noto2024/noto2024-04.html

According to an analysis of geodetic observation data by the Geospatial Information Authority ofJapan (GSI) (2024), an uplift of up to 4 m was reported in the Kaiso area, Monzen-machi, Wajima
City, Ishikawa Prefecture. At Kaiso Fishing Port (Fig. 4. (a) yellow point), oysters, serpulidae, andother organisms adhering to the seawall surface were observed to have been displaced by the uplift(Fig. 4. (b)). The upper altitude of the sessile organisms, which indicates the approximate preearthquake location of the sea surface, was measured at several points after the earthquake ranged
from 3.8 to 3.9 m. Figure 4 (c) shows a wave-cut shelf has dried up due to upheaval caused by theearthquake, as seen in the area north of the Kaiso fishing port. Wave-cut shelves, which are formed
by weathering of the bedrock and erosion by waves, are originally spread out at approximately theheight of the mean sea level. The front of the wave-cut shelf is a cliff (Fig. 4. (d)), and the differencein height from the sea level after the earthquake is approximately 3.6 m. Cross-sectional topographic
survey using a lightwave rangefinder revealed the terraced topography shown in Figure 4 (e),indicating the formation of marine terraces.

Fig. 5. Amount of crustal deformation based on 2.5D analysis of DAICHI-2 observation data (edited
to the figures posted on the website from Geospatial Information Authority of Japan updated
January 19, 2024: https://www.gsi.go.jp/uchusokuchi/20240101noto_insar.html
Figure 5 shows crustal deformation over the entire Noto Peninsula based on 2.5D analysis, usingobservation data from ALOS-2 (DAICHI-2). These results show a maximum uplift of approximately

4 m and a maximum westward movement of approximately 2 m in the western part of Wajima City.
A maximum uplift of approximately 2 m and a maximum westward variation of approximately 3 m
can be seen in the northern part of Suzu City.

Fig.6. ALOS-2 SAR intensity composite images acquired (a) before and (b) after the earthquake,
aerial photographs (c) before and (d) after the earthquake around Nafune-machi in Wajima City.
Red zones indicate the zones where the uplift associated with the earthquake was detected. Thesefigures are edited to Coastline change caused by the 2024 Noto Peninsula Earthquake detected by
ALOS-2 SAR satellite image (Jan. 4, 2024) posted on the website of Geospatial Information
Authority of Japan: https://www.gsi.go.jp/uchusokuchi/uchusokuchi-e31001.html
In the coastal area in Wajima City, an uplift of approximately 4 m was detected and the coastline
has changed by approximately 150 - 200 m along the coastal line (Fig.6).

Fig. 7. Slope Variation by Numerical
Topographic Image Analysis
KOKUSAI KOGYO CO., LTD

Geospatial Information Authority of Japan(GSI)(https://www.kkc.co.jp/disaster/2024/01/%e4%bb%a4%e5%92%8c%ef%bc%96%e5%b9%b4%e8%83%bd%e7%99%bb%e5%8d%8a%e5%b3%b6%e5%9c%b0%e9%9c%87/)

Numerical topographic image analysis (Patent No. 4545219) using detailed topographic data before
and after the earthquake was conducted in the area from northeast to southwest of the NotoPeninsula. In the northeastern part of the survey area, a 1500 x 1000 m area of land surface
displacement was observed on a mountain slope near Machino-machi, Wajima City (Fig. 7). The
ground surface displacement was divided into several blocks, and the maximum displacement of theslope, calculated by correcting the amount of displacement due to crustal deformation, wasapproximately 8 m.

Fig. 8. Linear steps seen inWakayama-machi of Suzu City
KOKUSAI KOGYO CO., LTDGeospatial Information
Authority of Japan (GSI)(https://www.kkc.co.jp/disaster/20
24/01/%e4%bb%a4%e5%92%8c%ef%bc%96%e5%b9%b4%e8%83%bd%e7%99%bb%e5%8d%8a%e5%b3%b6%e5%9c%b0%e9%9c%87/)

In the Wakayama-machi of Suzu City, linear deformations were found in the GSI survey. It has
confirmed a rise in the ground approximately 4 km long and 100 to 200 meters wide from east to west.
A maximum of 2.2 m high steps across fields and rivers were also observed. Aerial laser
measurements show steps as indicated by the white arrows in Figure 8. It is believed that the groundwas uplifted by strong compression in the north-south direction.

Fig. 9. Damage to buildings in Tagamishinmachi, Kanazawa City, Ishikawa Prefecture

Fig. 10. Damage to the Noto Satoyama Kaido
Road, that directly connects Kanazawa City tothe Noto Peninsula, Ishikawa Prefecture

Fig. 11. Collapse of slope along Route 249,
Matsunagi-machi, Suzu City, Ishikawa
Prefecture

Fig. 9., Fig. 10. And Fig. 11. are offered byKOKUSAI KOGYO CO., LTD and PASCOCORPORATION(https://www.kkc.co.jp/disaster/2024/01/%e4%bb%a4%e5%92%8c%ef%bc%96%e5%b9%b4%e8%83%bd%e7%99%bb%e5%8d%8a%e5%b3%b6%e5%9c%b0%e9%9c%87/)