Following high demand on detailed information for active faults in Japan after the 1995 Hyogokenn... more Following high demand on detailed information for active faults in Japan after the 1995 Hyogokennambu earthquake, we compiled completely new active faults map of Japan with a scale of 1:25,000 based on precise airphoto interpretation. We also digitized location of active fault traces and their parameters such as displacement, fault reference etc. to GIS data set. This digital fault map differs much in accuracy from "Active fault in Japan: Sheet map (1:200,000) and inventories" and may provide useful information to geoscientists and engineers for their purposes.
Earthquake Environmental Effect for seismic hazard assessment: the ESI intensity scale and the EEE Catalogue
ABSTRACT http://www.isprambiente.gov.it/it/pubblicazioni/periodici-tecnici/memorie-descrittive-de... more ABSTRACT http://www.isprambiente.gov.it/it/pubblicazioni/periodici-tecnici/memorie-descrittive-della-carta-geologica-ditalia/earthquake-environmental-effect-for-seismic-hazard-assessment-the-esi-intensity-scale-and-the-eee-catalogue In the last twenty years, the interest of scientific community towards Earthquake Environmental Effects (EEEs) has progressively increased especially in the frame of INQUA - International Union for Quaternary Research. In 2007 the ESI 2007 (Environmental Seismic Intensity scale) was published, a new intensity scale based only on EEEs resulting by a revision process taking about 8 years, and promoted by several geologists, seismologistsand engineers coordinated by Servizio Geologico d’Italia (now ISPRA). The ESI 2007 scale integrates traditional intensity scales, and allow to define seismic intensity based on the entire scenario of effects. In 2011 the EEE Catalogue was launched, a web infrastructure realized by ISPRA for data collection of EEEs induced by recent, historical and paleoearthquakes at global level. Cataloguing and classifying EEEs has allowed to compare past seismic events and to identify the most vulnerable areas in term of site effect. Some strong earthquakes occurred in the last years have unfortunately pointed out the primary role played by geological effects in the scenario of damages, confirming that seismic hazard cannot be evaluated only based on vibratory ground motion but also on the knowledge about EEEs. This volume provides the state of knowledge about these topics, with the aim to promote the use of the ESI 2007 intensity scale, that has been translated into ten languages, and the EEE Catalogue, as an helpful tool also for land planning, especially in high seismic hazard areas. Claudio CAMPOBASSO
Wereview progress of geological and geomorphological approaches in paleoseismology in Japan durin... more Wereview progress of geological and geomorphological approaches in paleoseismology in Japan during the this decade. We emphasize the growth of active fault studies since the 1995 Kobe earthquake. Two examples of intensive trenching studies, one on the Itoshizu-Tectonic Line in central Japan, and the other on the Miura Peninsula south of Tokyo, are briefly discussed with special reference to fault segmentation and the probability of large earthquakes. Studies of coastal morphology and deposits which are used for the reconstruction of paleoearthquakes are also reviewed. Japanese scientists have contributed much to paleoseismological studies overseas through collaborative international projects including identification of coseismic uplift, subsidence and tsunami deposits along the Pacific coasts as well as studies of inland faults.
Bulletin of the Seismological Society of America, 2004
Trenches across the Utsalady Point fault in the northern Puget Lowland of Washington reveal evide... more Trenches across the Utsalady Point fault in the northern Puget Lowland of Washington reveal evidence of at least one and probably two late Holocene earthquakes. The "Teeka" and "Duffers" trenches were located along a 1.4-km-long, 1to 4-m-high, northwest-trending, southwest-facing, topographic scarp recognized from Airborne Laser Swath Mapping. Glaciomarine drift exposed in the trenches reveals evidence of about 95 to 150 cm of vertical and 200 to 220 cm of left-lateral slip in the Teeka trench. Radiocarbon ages from a buried soil A horizon and overlying slope colluvium along with the historical record of earthquakes suggest that this faulting occurred 100 to 400 calendar years B.P. (A.D. 1550 to 1850). In the Duffers trench, 370 to 450 cm of vertical separation is accommodated by faulting (ϳ210 cm) and folding (ϳ160 to 240 cm), with probable but undetermined amounts of lateral slip. Stratigraphic relations and radiocarbon ages from buried soil, colluvium, and fissure fill in the hanging wall suggest the deformation at Duffers is most likely from two earthquakes that occurred between 100 to 500 and 1100 to 2200 calendar years B.P., but deformation during a single earthquake is also possible. For the two-earthquake hypothesis, deformation at Teeka trench in the first event involved folding but not faulting. Regional relations suggest that the earthquake(s) were M Ն ϳ6.7 and that offshore rupture may have produced tsunamis. Based on this investigation and related recent studies, the maximum recurrence interval for large ground-rupturing crustal-fault earthquakes in the Puget Lowland is about 400 to 600 years or less.
STREL'TSOV, M. I. KOZHURIN , A. I.8) BULGAKOV, R.7) TERENTIEF, N.9) IVASHCHENKO , A. I.7) Prelimi... more STREL'TSOV, M. I. KOZHURIN , A. I.8) BULGAKOV, R.7) TERENTIEF, N.9) IVASHCHENKO , A. I.7) Preliminary Report on Active Faults in Sakhalin , Russia Yasuhiro SUZUKI1), Hiroyuki TSUTSUMI2) , Mitsuhisa WATANABE3), Takeyuki UEKI4), Koji OKUMURA5), Hideaki GOT08), Mihail I . STRELTSoV7), Andrei I. KOZHURIN8),z Rustam BULGAKOV7), Nikolai TERENTIEF9) and Alexei I . IVASHCHENKo7
Physical environments including landforms have significantly affected human activities in ancient... more Physical environments including landforms have significantly affected human activities in ancient periods. Geographical analysis on such environments around archaeological sites is therefore essential for the understanding of ancient cultural developments. Although detailed topographic maps in remote areas are often limited, recent technologies including measurement equipment and GIS have enabled on-site acquisition of such maps for geographical surveys. Here we apply the methodology of laser measurement, SfM-MVS (structure-from-motion multi-view stereo) photogrammetry and GNSS (global navigation satellite system) for detailed, high-definition topographic mapping of characteristic landforms around archaeological settlements (mainly B.C. 3000 A.D. 1000) in Kayseri region, central Turkey. The landforms include alluvial fans, fault scarps, plains with lakes and hummocks in debris avalanche deposits. The resultant data, including high-resolution DEMs (digital elevation models) and ortho...
The Kumaun Sub-Himalaya region is one of the most active regions falling into Seismic Zone V alon... more The Kumaun Sub-Himalaya region is one of the most active regions falling into Seismic Zone V along the Himalaya. The geomorphology and drainage patterns in the area of active faulting and related growing fold provide significant information on the ongoing tectonic activity. The Kaladungi Fault (KF), an imbricated thrust fault of the Himalayan Frontal Thrust system provides an excellent example of forward and lateral propagation of fault and related folding in both directions along the strike of the fault. The KF has displaced the distal part of the Kaladungi fan surface resulting into formation of south-facing active fault scarp with variable heights along the front. In the east, the uplifted fan surface is ∼60 m, is comparatively higher in the central part with height of ∼200 m and ∼80 m high in the west. The variation in heights along the fault is attributed to lateral propagation of fault and associated fold in both directions (i.e. east and west) from the centre. These clearly t...
Bulletin of the Seismological Society of America, 2005
The North Anatolian Fault System (NAFS) is an approximately 2-110-km-wide, 1600-km-long right-lat... more The North Anatolian Fault System (NAFS) is an approximately 2-110-km-wide, 1600-km-long right-lateral intra-continental transform fault boundary between the Anatolian platelet and the Eurasian plate. The Gerede fault zone is one of the major active structures in the western section of the NAFS. It is a 1-9-km-wide, 325-km-long and ENE-trending dextral strike-slip fault zone, with a total accumulated offset since its initiation (Late Pliocene) of about 43 km. This offset indicates an average geological slip rate of 16.5 mm/yr. The 1 February 1944 Gerede earthquake occurred within the Gerede fault zone. Based on recent field geological mapping of the rupture traces and offsets on it, the average and peak lateral offsets were measured to be 4.37 m and 7.16 m, respectively. A triangulation network covering the region was first set up between 1936 and 1943. Twentyeigth existing points of the network were reoccupied by GPS receivers between 1995 and 2004. Coseismic displacements for the February 1, 1944 Gerede earthquake were obtained at the reoccupation points by removing interseismic deformation and coseismic displacements of recent earthquakes. Modelling the coseismic displacements in elastic half space resulted in a rupture surface slippage of 4.40 ± 0.11 m and 1.02 ± 0.17 m in dextral and normal dip-slip directions, respectively. The 191-km-long and 16-km-deep rupture surface strikes N76°E and dips at 85° ± 5°both to north and south. In the present study the estimated geodetic scalar moment and moment magnitudes are M o = 4.02 × 10 20 Nm and M w = 7.74, respectively. The rupture surface was extended down dip to a depth of about 28 km, and a significant slip distribution was recovered. Based on both the geodetic and geological data, the recurrence intervals for great seismic events to be sourced from the Gerede fault zone were calculated as 232 ± 25 years and 266 ± 35 years, respectively.
Trenching, microgeomorphic mapping, and tree ring analysis provide information on timing of paleo... more Trenching, microgeomorphic mapping, and tree ring analysis provide information on timing of paleoearthquakes and behavior of the San Andreas fault in the Santa Cruz mountains. At the Grizzly Flat site alluvial units dated at 1640-1659 A.D., 1679-1894 A.D., 1668-1893 A.D., and the present ground surface are displaced by a single event. This was the 1906 surface rupture. Combined trench dates and tree ring analysis suggest that the penultimate event occurred in the mid-1600s, possibly in an interval as narrow as 1632-1659 A.D. There is no direct evidence in the trenches for the 1838 or 1865 earthquakes, which have been proposed as occurring on this part of the fault zone. In a minimum time of about 340 years only one large surface faulting event (1906) occurred at Grizzly Flat, in contrast to previous recurrence estimates of 95-1 10 years for the Santa Cruz mountains segment. Comparison with dates of the penultimate San Andreas earthquake at sites north of San Francisco suggests that the San Andreas fault between Point Arena and the Santa Cruz mountains may have failed either as a sequence of closely timed earthquakes on adjacent segments or as a single long rupture similar in length to the 1906 rupture around the mid-1600s. The 1906 coseismic geodetic slip and the late Holocene geologic slip rate on the San Francisco peninsula and southward are about 50-70% and 70% of their values north of San Francisco, respectively. The slip gradient along the 1906 rupture section of the San Andreas reflects partitioning of plate boundary slip onto the San Gregorio, Sargent, and other faults south of the Golden Gate. If a mid-1600s event ruptured the same section of the fault that failed in 1906, it supports the concept that long strike-slip faults can contain master rupture segments that repeat in both length and slip distribution. Recognition of a persistent slip rate gradient along the northern San Andreas fault and the concept of a master segment remove the requirement that lower slip sections of large events such as 1906 must fill in on a periodic basis with smaller and more frequent earthquakes. Ellsworth, 1990; Marshall et al., 1991] have raised basic questions about the seismic behavior and earthquake potential of this segment of the San Andreas fault.
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Papers by Koji Okumura