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Malatesta, L. C.*; 末岡 茂; Wei
, N.-M.*; Gailleton, B.*; 塚本 すみ子*; 石村 大輔*; 高橋 直也*; 西村 卓也*; 片岡 香子*; 小松 哲也; et al.
Geophysical Research Letters, 52(24), p.e2025GL116602_1 - e2025GL116602_10, 2025/12
被引用回数：0 パーセンタイル：0.00(Geosciences, Multidisciplinary)The eastern margin of the Sea of Japan is a zone of great seismic and tsunami hazard due to multiple offshore and nearshore reverse faults as shown by the 2024 Mw7.5 Noto Peninsula Earthquake. Here we compare coseismic deformation of the 2024 Noto Peninsula Earthquake with 4,767 individual marine terraces attributed to 16 successive sea-level stages over the last Myr. This reveals that the earthquake faults started slipping between 326 and 238 ka. The emerged landscape is still adjusting to it while nearshore underwater scarps mark the active faults. Applied to nearby Sado Island, these observations reveal the likely location of an active fault that drives its fast deformation. Active faults defining the edge of uplifting land are likely found in the near shore domain, drowned by the current sea-level high stand.
Malatesta, L. C.*; 塚本 すみ子*; 末岡 茂; 小松 哲也; 高橋 直也*; 石村 大輔*; 片岡 香子*; 西村 卓也*; Weiss, N.-M.*; Keum, D.*; et al.
no journal, ,
The eastern margin of the Sea of Japan is a zone of great seismic and tsunami hazard due to multiple offshore and nearshore reverse faults. The 2024 Mw 7.5 Noto Peninsula Earthquake highlights this hazard. It resulted from the combined rupture of multiple adjacent faults. The specific hazard caused by each fault in the back-arc is however difficult to assess owing to long earthquake recurrence intervals. Diagnostic fingerprints in the landscape, onshore and offshore, can reveal clues and augment our understanding of the local earthquake cycle. Here, we compare coseismic deformation of the 2024 Noto Peninsula Earthquake with 4,767 individual marine terraces attributed to 16 successive sea-level stages over the last Myr. This reveals that the reverse faults responsible for the quake were reactivated and started slipping between 326 and 238 ka. The emerged landscape is still adjusting to it while nearshore underwater scarps mark the active faults. Applied to nearby Sado Island, these observations reveal the likely location of an active fault that drives its fast deformation. Active faults defining the edge of uplifting land are likely found in the near shore domain, drowned by the current sea-level high stand. New luminescence dating constraints on uplifted marine terraces further quantify the rate of deformation on Noto. These ages are in the final phase of analysis at the time of writing. Preliminary results appear to largely confirm the existing morphostratigraphic assumptions for the 120 ka terrace of Noto and a recurrence interval for 2024 Mw 7.5-type earthquake on the order of 2 kyr.
Malatesta, L.*; Weiss, N.-M.*; 石村 大輔*; Gailleton, B.*; 西村 卓也*; 高橋 直也*; 塚本 すみ子*; 小松 哲也; 岩佐 佳哉*; 末岡 茂; et al.
no journal, ,
本発表では、令和6年能登半島地震において発生した沿岸部の地形変化、特に隆起分布について着目し、それらと更新世の海成段丘群の高度分布との比較から、過去約100万年間の能登半島におけるテクトニクスや変動地形について考察した。
Malatesta, L.*; 末岡 茂; Weiss, N.-M.*; Gailleton, B.*; 塚本 すみ子*; 石村 大輔*; 西村 卓也*; 高橋 直也*; 片岡 香子*; 小松 哲也; et al.
no journal, ,
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. The coastline accordingly moved seaward by up to 200 m creating new wide bedrock platforms that could become marine terraces if they survive erosion and weathering. The Peninsula itself hosts 4767 unique mapped terraces ranging in age from Holocene to 1.02 Ma. 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. Most of the faults that ruptured on January 1st track the coast along a marked ramp at ca. 60 m below sea level. This corresponds to the average elevation of sea level over the last 500 kyr. 80 km to the northeast of the Noto Peninsula lies the Island of Sado where marine terraces record a strong southeast tilting similar to the Noto Peninsula. Earlier work suggested that the tilt is driven by a fault lying just offshore of the Oosado coast. The bathymetry reveals a ramp at around -60 m reflecting a geometry similar to the Noto Peninsula. This calls our attention to the often less-studied near-shore, and highlights a potential seismogenic source capable of 
M7 ruptures.
Malatesta, L.*; Weiss, N.-M.*; 塚本 すみ子*; 末岡 茂; 石村 大輔*; Gailleton, B.*; 西村 卓也*; 高橋 直也*; 片岡 香子*; 小松 哲也; et al.
no journal, ,
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. The coastal rocks uplifted as much as 4.4 m. The coastline accordingly moved seaward by up to 200 m creating new wide bedrock platforms. Holocene terraces mapped along the northern coast suggest similar past ruptures. Many of the ruptured faults follow the coast at a depth of ca. 60 m below modern sea level, which 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. The terraces associated with the last two interglacial high stands 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. 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 to the 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 suggested a hypothesis 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 and highlights a potential seismogenic source close to the shore.
Malatesta, L. C.*; 末岡 茂; Weiss, N.-M.*; 塚本 すみ子*; Gailleton, B.*; 石村 大輔*; 西村 卓也*; 高橋 直也*; 片岡 香子*; 小松 哲也; et al.
no journal, ,
能登半島地震による地殻変動と、能登半島に分布する海成段丘の地形・年代を分析し、半島の長期的な隆起や断層活動の特徴を調べた。特に、段丘の傾きや隆起の分布を比較することで、現在の主要断層がいつ支配的になったのかを明らかにすることを目的とした。研究の結果、約25万年前頃から現在の断層活動による南東方向への傾動が始まり、半島の地形はまだその隆起パターンに完全には適応していない過渡的状態にあると結論づけた。さらに、佐渡島周辺の海底地形との比較から、沿岸近くの断層がM7以上の地震を起こす潜在的な震源となる可能性を示した。
Malatesta, L.*; Weiss, N.-M.*; 塚本 すみ子*; 末岡 茂; 石村 大輔*; Gailleton, B.*; 西村 卓也*; 高橋 直也*; 片岡 香子*; 小松 哲也; et al.
no journal, ,
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. Recent Holocene terraces mapped along the northern coast, where coseismic uplift was greatest on January 1st 2024, suggest that they may be attributable to similar past ruptures. The Peninsula itself is remarkable for its 4767 unique terraces ranging in age from Holocene to 1.02 Ma. We digitized all terraces and recorded the elevation of their landward edge, and derived a rock uplift rate for each based on their age and the corresponding original sea level. The southeast-tilting crustal deformation recorded by the terraces associated with the last two interglacial high stands strongly resembles that caused by the Mw 7.5 earthquake. Older terraces, on the contrary all record a spatially uniform rate of uplift across the Peninsula. We conclude that the faults that caused the most recent earthquake became the dominant structures on the Peninsula over a quarter million year ago. This onset of seismogenic activity informs us about the regional plate tectonics of the area. The boundary separating Eurasia from the North American Plate currently runs south of the Noto Peninsula, linking the cities of Niigata and Kobe along a northeast-striking Tectonic Zone (NKTZ). Immediately east of the Peninsula lies another north-striking Tectonic Line, from Itoigawa to Shizuoka (ISTL). East of the ISTL and north of the NKTZ is the Island of Sado, which terraces also suggest a change in deformation with strong southeast tilting synchronous and similar to Noto. Together, Noto and Sado act as a railroad switch, indicating which of the ISTL or the NKTZ is the active plate boundary. When the ISTL is active, the sites are on different tectonic plates and evolve differently. When the NKTZ takes over, Sado Island becomes part of Eurasia and is more likely to evolve similarly to the Noto Peninsula.
