Field surveys of the 2024 Noto Peninsula earthquake tsunami in the areas distant from its source

Many tsunamis which were generated in the SE. Asia region hit the neighboring coasts of the source areas and some tsunamis were observed at the tidal stations of Japan. Tsunami magnitudes on the Imamura-Iida scale are investigated by the author's method 1 (HATORI, 1979, 1986) using the data of inundation heights near the source areas and the tide-gauge records in Japan. The regional characteristics of tsunami magnitudes are discussed in relation to earthquake magnitudes during the period from 1960 to 1993.Comparing with the statistical relation of earthquake magnitudes based on the data near Japan and great earthquakes in the world, the magnitude values of the Taiwan tsunarmi sunamis showed relatively to be small. On the contrary, the magnitudes of tsunamis in the vicinities of Philippine and Indonesia exceed more than 1-2 grade (tsunami heights: 2-5 times) compared with the same earthquake magnitude of other regions. The relation between tsunami magnitude, m, and earthquake magnitude, Ms, is expressed as m=2.66Ms-17.5 for these regions. For example, the magnitudes for the 1976 W. Mindanao tsunami (Ms=7.8, 3702 deaths) and the 1992 N. Flores Is. tsunami (Ms=7.5, 1713 deaths) were determined to be m=3 and m=2.5, respectively.The focal depth of tsunamigenic earthquakes is shallower than d<36km, and the detectivity of tsunamis is small for deep earthquakes being d>40km. For future tsunamis, it is indispensable to take precautions against shallow earthquakes having the magnitudes Ms<7.0.

The regional characteristics of tsunami magnitudes in the SE Asia region are discussed in relation to earthquake magnitudes during the period from 1960 to 1994. Tsunami magnitudes on the Imamura-Iida scale are investigated by the author's method (Hatori 1979, 1986) using the data of inundation heights near the source area and tide-gauge records observed in Japan. The magnitude values of the Taiwan tsunamis showed relatively to be small. On the contrary, the magnitudes of tsunamis in the vicinities of the Philippines and Indonesia exceed more than 1–2 grade (tsunami heights: 2–5 times) compared to earthquakes with similar size on the circum-Pacific zone. The relation between tsunami magnitude, m, and earthquake magnitude, Ms, is expressed as m = 2.66 Ms− 17.5 for these regions. For example, the magnitudes for the 1976 Mindanao tsunami (Ms= 7.8, 3702 deaths) and the 1992 Flores tsunami (Ms= 7.5, 1713 deaths) were determined to be m = 3 and m = 2.5, respectively. The focal depth of tsunamigenic earthquakes is shallower thand 40 km. For future tsunamis, it is indispensable to take precautions against shallow earthquakes having the magnitudes Ms> 6.5.

The Noto Peninsula earthquake occurred on January 1, 2024, with an MJ of 7.6. This earthquake was triggered by active submarine faults previously mapped off the northern coast of the Noto Peninsula and generated a tsunami. We mapped the tsunami inundation areas and tsunami runup and inundation heights associated with the 2024 earthquake along the coast of the entire Noto Peninsula based on high-resolution aerial photographs and field surveys. The tsunami inundation area was widely distributed along the coast of the Noto Peninsula, Hegurajima, and Notojima Islands. The tsunami inundation area was 3.7 km2 in total. The tsunami inundation areas were distributed continuously along the west and east coasts of the Noto Peninsula. In contrast, these were discontinuous along the northern coast of the Noto Peninsula. The characteristics of the regional patterns of the tsunami inundation were broadly consistent with the tsunami inundation assumptions made for tsunami hazard maps before the 2024 earthquake. The tsunami height was different between the east and west coasts of the Noto Peninsula, with a peak of 11.3 m in elevation at Kuroshima. The tsunami on the west coast was higher than the one on the east coast. This was due to the location of the earthquake source fault and the distribution of the slip amount of the fault. The distribution of tsunami heights is also influenced by tsunami propagation characteristics, such as reflection and refraction. The tsunami runup and inundation height of the 2024 earthquake was the largest along the coast of the northern Noto Peninsula since the twentieth century compared with the past earthquakes. In contrast to the tsunami height, damages induced by the tsunami were smaller along the west coast and larger along the east coast, which was attributed to the location of the settlements and the presence of coastal structures. This study will contribute to future tsunami disaster prevention along the Sea of Japan coastlines crucial for improving future response strategies by accurately determining tsunami height and potential damage.Graphical

A large tsunami was generated off East Hokkaido at 22:23 (JST) on Oct. 4, 1994. According to JMA, the epicenter of the main shock was located at 43°22′N, 147°40′ E with a depth of 30km and earthquake magnitude, M=8.1. The tsunami hit Shikotan, Kunashiri Islands, and double-amplitude reached 342cm at Hanasaki. Wave-periods of about 40min were predominant on tide-gauge records at Hokkaido and Sanriku stations. The aftershock area which nearly corresponding to the tsunami source is 200×100km, extending along the Kurile trench. The tsunami source area was lapped over that due to the 1969 Shikotan earthquake (M=7.8). Tsunami magnitude on the Imamura-Iida scale was determined to be m=3 judging from the tsunami height-distance diagram. This value is normal compared to earthquake with similar size in other regions. On the relation between tsunami height and earthquake magnitude for the East Hokkaido tsunamis since 1918, the heights at Hanasaki are scattered, but about three times higher than those of the Etorofu-Urup tsunamis. The ratios of tsunami heights at the Sanriku coast to the initial semi-amplitude at Hanasaki were about 0.5, but those of the big bays (seiche period of 40-50min) reached 2.0. On the contrary, the amplitude ratios at the Hokkaido coast facing the Okhotsk Sea are 0.4 or less. Tsunami heights at Ogasawara-Chichijima Is. often deviated more than twice time higher than the average tsunami magnitude because of the refractive effect.

The Japan Meteorological Agency (JMA) released a new version of tsunami warning system using three qualitative expressions for tsunami height. Understanding disaster mitigation information requires adequate knowledge on disaster occurrence mechanisms and precise action in emergencies. We surveyed differences in understanding and assessing tsunami warning information among university students in two prefectures – one damaged by the 2011 off Pacific Coast of Tohoku Earthquake and the other outside of the damage zone. Results revealed that those outside of the damage zone tended to estimate tsunami heights as higher than those inside the damage zone when reading qualitative tsunami heights in the JMA’s new tsunami warning version. They also tended to need more concrete, precise information to understand appropriate evacuation procedures provided by public institutions, including the JMA.

On January 1st, 2024, the Mw 7.5 Noto Peninsula earthquake ruptured on a series of coastal offshore reverse faults in the back arc of central Japan. Closest to the rupture, in the northwest, the coastal rocks uplifted as much as 4.4 m (Fukushima Yo et al., 2024). The coastline accordingly moved seaward by up to 200 m creating new wide bedrock platforms. Recent Holocene terraces mapped along the northern coast (Shishikura et al., 2020), where coseismic uplift was greatest on January 1st 2024, suggest similar past ruptures. Many of the ruptured faults follow the coast at a depth of ca. 60 m below modern sea level. This is the average elevation of sea level over the last 500 kyr, and strongly suggests that these faults define the extent of the continental domain.The Peninsula itself hosts 4767 unique mapped terraces ranging in age from Holocene to 1.02 Ma (Ota and Hirakawa, 1979, Koike and Machida, 2001). The terraces associated with the last two interglacial high stands (ca. 120 and 234 ka) record a tectonic SE-tilting similar to that of the Mw 7.5 earthquake. Older terraces all record a spatially uniform rate of uplift across the Peninsula. The landscape itself does not appear to be equilibrated to this gradient in uplift, with a seemingly disconnected fluvial geometry. We conclude that the faults that caused the most recent earthquake became the dominant structures on the Peninsula around 250 ka and that the Peninsula is in a state of transient equilibration.80 km northeast of the Noto Peninsula lies the Island of Sado. The Island is made of two mountain ranges oriented SW-NE along the main tectonic lineation of the back arc, roughly parallel to the northern coast of Noto Peninsula. The marine terraces of the northern range, Oosado, record a strong southeast tilting synchronous and similar to that observed on the Noto Peninsula. The landscape morphology is not equilibrated to this pattern of deformation either. Earlier work by Ota et al., (1992) suggested that the tilt is driven by a fault lying just offshore of the Oosado coast. Closer inspection of the bathymetry reveals a ramp at around -60 m reflecting a geometry similar to the Noto Peninsula. The lessons from the Noto Peninsula earthquake can be applied to Sado Island where information about the seismic cycle is lacking. It confirms the hypothesis of Ota et al. (1992) and highlights a potential seismogenic source close to the shore.&amp;#160;Koike, K., &amp;amp; Machida, H. (2001). Atlas of Quaternary&amp;#8230; Tokyo: University of Tokyo Press.Ota, Y., &amp;amp; Hirakawa, K. (1979). Marine terraces and&amp;#8230; Geographical Review of Japan, 52(4), 169&amp;#8211;189.Ota, Y., Miyawaki, A., &amp;amp; Shiomi, M. (1992). Active Faults on Sado Island&amp;#8230; Journal of Geography (Chigaku Zasshi), 101(3), 205&amp;#8211;224.Shishikura, M., Echigo, T., &amp;amp; Namegaya, Y. (2020). Activity of the off-shore&amp;#8230; Active Fault Research, 53, 33&amp;#8211;49. Fukushima, Y., Ishimura, D. et al. (2024). Landscape changes caused by... Science Advances, 10(49), eadp9193. https://doi.org/10.1126/sciadv.adp9193

A large crustal earthquake (Mw=7.5) struck the Noto Peninsula, central Japan, at 16:10 (JST = UT + 9 hours) on New Year's Day, 2024. The main-shock rupture extended ~150 km in length, which covered the source regions of intense swarm activity in the northeastern tip of the peninsula [Amezawa et al., 2023] as well as the previous large crustal earthquakes such as the 2007 (Mw=6.7) and 2023 (Mw=6.3) events. The aftershock distribution of the 2024 event provides fundamental information for understanding the rapture process of the main shock and seismotectonics in the Noto peninsula. Therefore, we relocated the earthquake hypocenters that occurred immediately after the 2024 event by considering the three-dimensional velocity structure [Matsubara et al., 2022]. In the relocation, we applied the method proposed by Shiina and Kano [2022] to the arrival time data on the earthquake catalog compiled by the Japan Meteorological Agency. The applied method utilized the Markov Chain Monte Carlo technique, allowing us to evaluate uncertainty in hypocenter locations. Thus, we can discuss the distributions of the crustal earthquakes in and around the source area of the 2024 event, taking account of the spatial variations in uncertainty in the hypocenters. For example, some aftershocks occurred offshore, indicating that estimation accuracy in that area may get worse due to limited station coverage compared with the inland area. As the result of the relocation considering the three-dimensional structure, the depth of these offshore events was shifted about 5 km shallower. These hypocenters suggested that the aftershocks of the 2024 event occurred mainly between the ground surface and the depth of 15 km.

A large shallow earthquake occurred in the Noto Peninsula on March 25, 2007. The Japan Meteorological Agency (JMA) estimated the hypocenter and origin time to be 136.685E, 37.220N and 09:41:57.9 JST, respectively, and the depth to be 11 km. The magnitude of the main shock is Mj (JMA scale) 6.9 and Mw 6.6, and the focal mechanism of the main shock is a reverse fault with right-lateral components. The strike, dip and rake are 58◦, 66◦ and 132◦, respectively, according to the National Research Institute for Earth Science and Disaster Prevention (NIED). The two largest aftershocks of Mj 5.4 occurred at the northeast and southwest edges of the aftershock area, at 18:11 on May 25 and at 07:16 on May 26, respectively. A maximum seismic intensity, 6 upper on the JMA scale, was observed at several stations situated in the source area. The earthquake caused severe damage on the Noto Peninsula and in the surrounding prefectures of Ishikawa, Toyama, Niigata and Fukui. The final report of the Fire and Disaster Management Agency reported one human fatality, 356 people injured and 29,349 houses completely and partially collapsed. Although several moderate-sized earthquakes had occurred in the northeast and southern parts of Noto Peninsula prior to this event, there is no record of large earthquakes with M > 7 occurring in this area during the last 1500 years. In addition, events of M 6.0 ∼ 6.5 have never occurred in the source region of the March 25, 2007 earthquake, and even the seismic activity of small and microearthquakes has been very low for more than 25 years, based on the high-gain seismic-observations by the Kamitakara Observatory, Kyoto University (Ito et al., 2007). Large active faults have not been identified on land in the source area. Nevertheless, some offshore faults in west off Noto Peninsula have nearly the same strike as that of the aftershock area, which may be related to the March 25, 2007 earthquake. Well-arranged high-density nation-wide networks have been constructed, and these provided abundant data for the sequence of the earthquake. In particular, strong-motion and high-gain earthquake records as well as the GPS data provided fundamental information on the earthquake sequence and related phenomena from immediately after the main shock. In addition, temporary dense seismic stations were deployed for aftershock observations

A field survey of the June 3, 1994 East Java earthquake tsunami was conducted within three weeks, and the distributions of the seismic intensities, tsunami heights, and human and house damages were surveyed. The seismic intensities on the south coasts of Java and Bali Islands were small for an earthquake with magnitude M 7.6. The earthquake caused no land damage. About 40 minutes after the main shock, a huge tsunami attacked the coasts, several villages in East Java Province were damaged severely, and 223 persons perished. At Pancer Village about 70 percent of the houses were swept away and 121 persons were killed by the tsunami. The relationship between tsunami heights and distances from the source shows that the Hatori’s tsunami magnitude was m = 3, which seems to be larger for the earthquake magnitude. But we should not consider this an extraordinary event because it was pointed out by Hatori (1994) that the magnitudes of tsunamis in the Indonesia-Philippine region generally exceed 1–2 grade larger than those of other regions.

Seismic intensity provides useful information on the regional distribution of earthquake effects and has been used to assess seismic hazards and damages. The concept of intensity has been considered as a method to classify severity of the ground motion on the basis of observed effects in the stricken area. In 1996, the Japan Meteorological Agency (JMA) developed a new seismic intensity measurement scale using three‐component strong ground motion records in order to provide a measure of the strength of the seismic motion, which is compatible with the existing JMA intensity scale. By applying a band‐pass filter to the frequency domain and a vectoral composition of the three components in the time domain, the JMA seismic intensity scale (I JMA ) can be calculated without subjective judgement. In this study, we apply the I JMA method to the acceleration records of three recent significant earthquakes in California. For a Modified Mercalli Intensity (MMI) between IV and VIII, a new relation between MMI and log a 0 , obtained in the process of calculating the new I JMA , is given by the equation MMI=3.93 log a 0 −1.17. We propose this relation as a new instrumental seismic intensity (I MM ) compatible with the California region MMI.

We explored the distributional changes in tsunami height along the eastern coast of the Korean Peninsula resulting from virtual and historical tsunami earthquakes. The results confirm significant distributional changes in tsunami height depending on the location and magnitude of earthquakes. We further developed a statistical model to jointly analyse tsunami heights from multiple events, considering the functional relationships; we estimated parameters conveying earthquake characteristics in a Weibull distribution, all within a Bayesian regression framework. We found the proposed model effective and informative for the estimation of tsunami hazard analysis from an earthquake of a given magnitude at a particular location. Specifically, several applications presented in this study showed that the proposed Bayesian approach has the advantage of conveying the uncertainty of the parameter estimates and its substantial effect on estimating tsunami risk.

Based on the tsunami data in the Central American region, the regional characteristic of tsunami magnitude scales is discussed in relation to earthquake magnitudes during the period from 1900 to 1993. Tsunami magnitudes on the Imamura-Iida scale of the 1985 Mexico and 1992 Nicaragua tsunamis are determined to be m = 2.5, judging from the tsunami height-distance diagram. The magnitude values of the Central American tsunamis are relatively small compared to earthquakes with similar size in other regions. However, there are a few large tsunamis generated by low-frequency earthquakes such as the 1992 Nicaragua earthquake. Inundation heights of these unusual tsunamis are about 10 times higher than those of normal tsunamis for the same earthquake magnitude (M s = 6.9–7.2). The Central American tsunamis having magnitude m > 1 have been observed by the Japanese tide stations, but the effect of directivity toward Japan is very small compared to that of the South American tsunamis.

On January 1, 2024, a devastating M 7.6 earthquake struck the Noto Peninsula, Ishikawa Prefecture, Japan, resulting in significant casualties and property damage. Utilizing information from the first six days after the earthquake, this article analyzes the seismic source characteristics, disaster situation, and emergency response of this earthquake. The results show: 1) The earthquake rupture was of the thrust type, with aftershock distribution showing a north-east-oriented belt-like feature of 150 km. 2) Global Navigation Satellite System (GNSS) and Interferometric synthetic aperture radar (InSAR), observations detected significant westward to north-westward co-seismic displacement near the epicenter, with the maximum horizontal displacement reaching 1.2 m and the vertical uplift displacement reaching 4 m. A two-segment fault inversion model fits the observational data well. 3) Near the epicenter, large Peak Ground Velocity (PGV) and Peak Ground Acceleration (PGA) were observed, with the maxima reaching 145 cm/s and 2681 gal, respectively, and the intensity reached the highest level 7 on the Japanese (Japan Meteorological Agency, JMA) intensity standard, which is higher than level 10 of the United States Geological Survey (USGS) Modified Mercalli Intensity (MMI) standard. 4) The observation of the very rare multiple strong pulse-like ground motion (PLGM) waveform poses a topic worthy of research in the field of earthquake engineering. 5) As of January 7, the earthquake had left 128 deaths and 560 injuries in Ishikawa Prefecture, with 1305 buildings completely or partially destroyed, and had triggered a chain of disasters including tsunamis, fires, slope failures, and road damage. Finally, this paper summarizes the emergency rescue, information dissemination, and other disaster response and management measures taken in response to this earthquake. This work provides a reference case for carrying out effective responses, and offers lessons for handling similar events in the future.

The Noto Peninsula earthquake struck the coast of the Noto Peninsula, Japan on March 25, 2007, resulting in the death of one woman and injury to 356 people. A total of 684 houses were totally destroyed by this earthquake, and more than 2,500 people were forced to live at shelters. In this study, we have evaluated the association between the incidence of peripartum abnormalities and seismic intensity of the Noto Peninsula earthquake. Demographic data, births, seismic intensity of the earthquake and the incidence of peripartum abnormalities between June 25, 2007 and January 31, 2008 were surveyed. The dataset included 126 pregnant women who lived in the disaster area. The seismic intensity of the earthquake was expressed on the scale (0-7, with 7 being the strongest measure) used by the Japan Meteorological Agency. The subjects of the analysis included 19.7% of the pregnant women affected by the disaster. Of the pregnant women included in this study, 7.9% had a premature rupture of membranes (PROM), with the percentage being significantly higher in the group that experienced a seismic intensity of 6 than in that experienced a seismic intensity of 5. Our epidemiologic study shows that the PROM among our study cohort was associated with seismic intensity, suggesting that the physical outcome was due to aftershocks of the earthquake at a seismic intensity ≥6. This outcome may result from the psychological stress caused by the earthquakes.

The February 2011 Christchurch, New Zealand, earthquake was highly destructive, causing a number of buildings to collapse and killing many people. We examined the properties of strong ground motions in this earthquake using the records released by GeoNet (http://www.geonet.org.nz/). We also investigated the damage around the seismic stations to determine the relationship between structural damage and strong ground motions. The locations of the seismic stations in our study are shown in Figure 1. Accelerograms and the elastic acceleration response spectra, with a damping factor of 0.05 in the maximum horizontal direction, are shown in Figures 2 and 3, respectively. Peak ground accelerations (PGA) and peak ground velocities (PGV) are shown in Table 1. Ij and I 1–2 are also shown in Table 1. Ij is JMA (Japan Meteorological Agency) seismic intensity (Tables 2, 3 and 4). It is publicly used to describe the damaging power of seismic shaking in Japan. I 1–2 is also an index like Ij . It was defined by Sakai, Kanno, and Koketsu (2002, 2004) based on elastic responses between 1 and 2 seconds period that were closely related with heavy structural damage (the subscript 1–2 means between 1 and 2 seconds) and represents the damaging power of an earthquake much better than Ij . View this table: TABLE 1 Seismic Intensity of Strong Ground Motions and Damage Conditions around the Seismic Station. View this table: TABLE 2 Explanation of JMA seismic intensity scales (http://www.jma.go.jp/) for human perception and reaction; indoor situations and outdoor situations View this table: TABLE 3 Explanation of JMA seismic intensity scales (http://www.jma.go.jp/) for wooden houses View this table: TABLE 4 Explanation of JMA seismic intensity scales (http://www.jma.go.jp/) for reinforced-concrete buildings As shown in Figures 2 and 3, the records of stations REHS, CCCC, …