Late Quaternary activity of the Haramachi segment of the Futaba Fault in Northeast Japan through topographic anaglyph images and borehole core sediment analysis.
In: Rudarsko-Geolosko-Naftni Zbornik, Jg. 38 (2023-04-01), Heft 2, S. 157-174
Online
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Zugriff:
The Haramachi Fault segment in the northeastern part of Honshu Island, Japan, has mainly sinistral fault movements with minor reverse component within the Futaba Fault Zone in the northeastern Japan arc. The 2011 Mw 9.0 earthquake occurred off the Pacific coast of Tohoku which caused large crustal deformations. Despite being the closest active fault to the epicenter, very limited investigation has been conducted on the Futaba Fault Zone. Previous studies used smaller scale topographic maps and fault activity was estimated only from trenching and borehole investigations in the central part of the Haramachi Fault segment. Thus, geometry, kinematic, and recent tectonic activity of the fault segment is not well identified, especially in northern part. In this study, we use a combination of high-resolution DEMs (2-m and 5-m mesh), several types of topographic anaglyph images (slope, negative and positive openness), and conducted field survey to confirm remote sensing interpretation. Subtle surface expression of deformation associated with active faulting, such as deformed terrace risers, deflected drainages, and small fault scarps can now be identified more clearly. Several new fault strands in the northern part of the segment were found supported by fault outcrops found in the field confirming the recent activity of the fault system. The new estimation of the total length of the Haramachi segment produced from the approach of this study yields 25 km, which is capable of producing Mw 6.5 - 7.0 or Mjma 7.2 earthquakes if ruptures were to occur altogether in the future. Moreover, a shallow borehole survey and radiocarbon dating from the soil organic material has revealed the minimal timing estimation of the most recent faulting in the Haramachi segment to be 3694 ± 24 BP. This research provides a revised understanding of active fault distribution and deformation associated with the Haramachi segment and validates the timing of the most recent faulting event more broadly. [ABSTRACT FROM AUTHOR]
Segment rasjeda Haramachi, dio je Fatuba rasjedne zone u sjeveroistočnom dijelu Japanskog luka, na otoku Honshu. Segment rasjeda Haramachi ukazuje uglavnom na lijeve pomake rasjeda s manjom reversnom komponentom. Potres intenziteta 9,0 Mw dogodio se 2011. godine u blizini pacifičke obale Tohokua koji je izazvao velike deformacije kore. Unatoč tome što predstavlja aktivni rasjed najbliži epicentru, u zoni rasjeda Futaba provedena su vrlo ograničena istraživanja. U prethodnim istraživanjima korištene su topografske karte manjeg mjerila, dok je aktivnost rasjeda procijenjena samo na temelju istraživanja izrađenih rovova i bušotinskih podataka u središnjem dijelu segmenta rasjeda Haramachi. Stoga, geometrija, kinematika, kao i nedavna tektonska aktivnost segmenta rasjeda nije dobro identificirana, osobito u sjevernom dijelu. U ovom istraživanju korištena je kombinacija DEM-ova visoke razlučivosti (mreža od 2 m i 5 m), nekoliko vrsta topografskih anaglifskih prikaza (nagib, negativna i pozitivna otvorenost), kao i terensko istraživanje kako bi se potvrdila interpretacija podataka dobivenih daljinskim istraživanjima. Neznantne površinski izražene deformacije povezane s aktivnim rasjedanjem, kao što su izdignute deformirane terase, pomaknute drenaže i mali pomaci rasjeda vidljivi na površini mogu se sada jasnije identificirati. Nedavna aktivnost rasjednog sustava vidljiva je kroz identifikaciju nekoliko novih rasjeda, čije je postojanje potkrijepljeno rezultatima terenskih istraživanja. Nova procjena ukupne duljine Haramachi segmenta dobivena pristupom iz ovog istraživanja iznosi 25 km, što može proizvesti potres od 6,5 - 7,0 Mw ili 7,2 Mjma. Štoviše, ispitivanje plitkih bušotina i datiranje ugljika iz organskog materijala tla otkrilo je minimalnu vremensku procjenu najnovijeg rasjedanja u Haramachi segmentu na 3694 ± 24 BP. Ovaj pristup revidirao je razumijevanje aktivne distribucije rasjeda i deformacija povezanih s Haramachi segmentom i potvrdio vrijeme najnovijeg događaja rasjedanja u širem smislu. [ABSTRACT FROM AUTHOR]
Titel: |
Late Quaternary activity of the Haramachi segment of the Futaba Fault in Northeast Japan through topographic anaglyph images and borehole core sediment analysis.
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Autor/in / Beteiligte Person: | Puji, Anggraini Rizkita ; Takahashi, Naoya ; Toda, Shinji |
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Zeitschrift: | Rudarsko-Geolosko-Naftni Zbornik, Jg. 38 (2023-04-01), Heft 2, S. 157-174 |
Veröffentlichung: | 2023 |
Medientyp: | academicJournal |
ISSN: | 0353-4529 (print) |
DOI: | 10.17794/rgn.2023.2.12 |
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