DOCSLIB.ORG

The Western Pacific Margin

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Western Pacific Margin 19 0 by Seiya Uyeda The Japanese island arc and the subduction p ro cess A C AL C- A LK A L INEANDE S ITE S HI G H ST R E S S (C HI L E A N ) TY P E P OR PH YR Y COP PE R MOUNT AI N BE L T L A RGE SUP P L Y O F T E RR IGE NOUS M A TE R IAL 尸 ingtrastingcific the counterparts.The Japanese characteristics western Pacificisland The Japaneseto arc, subduction those in generalof arc the zones, itself eastern have consistsinclud- con- Pa- 一 — 一 — 一一 SH A LLO W ．一弃 - U PLIFT 名 二 二王二宾于 牛-TRFNCH- 互二墓葬梦 二一一二-PRONOUNCED BULC二一二甲二弓蕊夔笔毫 , ＋ ． ofJapanSometwo results arearcs systems: thatof'recent also the eastinvestigationshave Japan contrasting arcs on and the features. the tecton- west Y.U.G PLATE ics and deeper structures of these subduction zones are reviewed . 豁ER, SAIIIIA IVEN ，镶囊舞瘫爵 C om parative subductology and general B features of the Japanese subduction zone L OW ST R E S S (MA RI AN A ) TY P E B AS AL T S K UR OKO F E W ANDE S IT E S T he Japanese subduction zone forms。。important part of the chain RI D GE TYP E BAS AL T S of subduction zones in the western Pacific margin. The other major BA CKA RC SPRE ADI N G system of subduction zones is the Peru-Chile system along the east- 日A RRE N TR EN CH WAL L ern rim of the Pacific. Subduction zones of these tw o systems generally have major contrasting characteristics. Typically, the west- 一 辱奏友李习 ern Pacific subduction zones form island arcs w ith backarc basins, 令点燕，今 w h ereas the eastern Pacific on es form co ntine ntal arcs with C ord ille- OL D PL AT E ran mountain ranges in their backarc regions. The end mem bers of these subduction zones are called , in term s of com parative subduc- tology Wy eda and Kanam ori, 1979; Uyeda, 1982 , 1983), the M ari- ana type, where backarc spreading is in action, and the Chileantype, J谁，荃卜哎 J 勺 J CO 工卜02 卜 巴 可 山 w here the backarc is under a com pressional stress regime. M ajor features characteristic to these two types of subduction zones are sum m arized in figure I． The fundam ental cause that gives rise to the contrasting features 淤 脂 却 depicted in figure I is the difference in the degree of physical coupling between subducting and overriding plates; the coupling is strong in the Chilean-type and weak in the M ariana-type subduction zones. It is not quite clear w hat causes the different degrees of physical coupling , although several possibilities have been put for- F igure I 一Cartoon diagram s show ing the two ideal m odes of w ard, including the difference in age of subducting plates. conver- subduction with possible tectonic implications and causes (not to gence rate, motion of overriding plate relative to trench axis, direc- scale). tion of sublithospheric flow , and the physical nature of plate interface, such as asperity (K anam ori, 1986). Recently. Shimarnoto and others （19911 have show n that there is a close correlation be- E urasian plate in the northern portion and beneath the Philippine Sea tween the size of maximum interplate earthquakes and the width of plate in the southern portion. There is a view that this part of the that part of the contact plane that is estimated to be seism ogem c from E urasian plate joined the North Am erican plate a couple of million or therm al and Theological features. so years ago when collision in H okkaido caused a jum p of the The Japanese subduction zones, in this paper. cover the region convergent plate boundary between the North Am erican and Eurasian extending from the Kuriles in the north to the Philippine Sea in the plates from central Hokkaido to the line along the eastern rim of the south (fig. 2). Thev are subdivided into the follow ing tw o system s: Sea of Japan and the ]toigaw a-Shizuoka Tectonic Line (IST L) in the east Japan arcs that com prise Kurile, northeastern Honshu, Izu- central Honshu as show n in figure 2 (Nakam ura, 1983). This vie" B onin, and M ariana subduction zones; and the w est Japan arcs, explains the occurrence of a series of thrust-type earthquakes along com prising southw estern H onshu and R yukyu subduction zones. the eastern rim of the Sea of Japan and proposes an interesting A long the fanner system . old Pacific plate is subducting beneath the possibility that the Sea of Japan coast of northeast Honshu is in the Septem ber /991 191 junction owing to the colliding unsubductable Izu Peninsula. while Peninsula. Izu unsubductable colliding the to owing junction the ISTL is essentially a thrust fault along the western rim of theof rim western the along fault thrust a essentially ISTLis the Fossa Magna.Fossa Another T-T-T-type triple junction, the Off Central Honshu Central Off the junction, triple T-T-T-type Another Eur一‘an，一少 (McKenzieexample classic a is which 2), fig. in (och junction triple and Morgan, 1969) and unique in the present-day globe. is formed t( formed is globe. present-day the in unique and 1969) Morgan, and rIaL.e sense the in unstable is junction triple This area. Kanto the of east the SEAOF rni- it if stabilized bewould and (1969) MorganMcKenzieand of JAPAN-> i} configuration present the If trough. Suruga the to westward grated 吮 户 "North overriding the of tip southeastern the be maintained, to American" plate will be continuously destroyed. Even if such tec- such Evenif destroyed. continuously be will plate American" 护：犷 still will junction triple Plate the of position the place, takes erosion tonic 峨 叹一 一 一 the in production plate sufficient is there unless movewestward, ‘～～一～example (for plate Sea Philippine retreating the of portion northern Carlson and Mortera-Gutierrez, 1990). According to the intense the to According 1990). Mortera-Gutierrez, and Carlson SHIKOKiLi\BASIN 少 0履汹 么 一 么as area, the of morphology the Project, Kaiko the of investigation well as the history of the Philippine Sea plate motion. is higbl} is motion. plate Sea Philippine the of history the as well complex, and conflicting views have been expressed on the tectonic the on expressed been have views conflicting and complex, evolution of this triple junction (for example. Seno and others, 1989: others, and Seno example. (for junction triple this of evolution 续 ＼ 嘴长～ ～ Houchonofsub-andLabaume, thickness the Furthermore, 1989). 生 MARIANAbeneath intercalating material plate Sea Philippine and Pacific ducted Philippine S e2 and Pichon (Le area the of evolution tectonic the complicates area the 戮 TROUGH C／ 1！11 subducting is plate Sea Philippine the west. Further 1987). Houchon, 飞 ＼ Ryukyu the and trough Nankai the at plate Eurasian the beneath 令 trench. ，‘ 一 水 一．一 ／ ／／ PARECEVELA ／ BASIN westand east the Comparisonof ／ Japanarcs Figure 2. -Outline index map of the Japanese subduction zones. subduction Japanese the ofmap index -Outline 2. Figure Thick lines with teeth are converging plate boundaries. Arrows boundaries. plate converging are teeth with lines Thick distinct show to tend arcs Japan east the of zones subduction The features that are considered to be inherent to the typical trench- typical the to inherent be to considered are that features indicate relative plate motions. su, Suruga trough; sa, Sagami sa, trough; Suruga su, motions. plate relative indicate 3showssomeeast-west figure example, For setting. arc-backarc trough; sf, South Fossa Magna triple junction; och, Off CentralOff och, junction; MagnaFossa South triple sf, trough; Honshuthenortheastofcrosssections about 40' N.Featuresarcat to Honshu triple junction; ISTL, Itoigawa-Shizuoka Tectonic Line; Tectonic ISTL,Itoigawa-Shizuoka junction; Honshutriple be noted include the Japan Trench and its pronounced negative pronounced and its Trench Japan the include noted be KSM,KashimaVLBIstation. free-air gravity anomaly, the Japan backarc basin and its negligibly its and basin backarc Japan the anomaly, gravity free-air small gravity anomaly and an oceanic crust. the almost-continentai the crust. oceanic an and anomaly gravity small incipient stage of slow eastward subduction. This view also provides also view This subduction. eastward slow of stage incipient Pnlow anomalously has that Honshu arc northeast the of crust a logical reason why the ISTL became a major thrust boundary and aand boundary thrust major a becameISTL whythe reason logical a flow heat high the and side trench the on flow heat low the velocity, rapid uplift of the so-called Japan Alps mountains started in early in started mountains Alps Japan so-called the of uplift rapid the volcanoes, active of front awell-defined backarc onside, the Pleistocene time. Plate boundaries shown in figure 2 are based on based are 2 figure shownin boundaries Plate time. Pleistocene high- landward-dipping aand seismicity, thrust interplate intense this view. this a andforming seismicity deep having slab lithospheric V-high-Q Recent results of very long baseline interferometry (VLBI) interferometry baseline long very of results Recent (for study electromagnetic Recently, zone. Wadati-Benioff double measurement, one of the major studies of the Japanese Dynamics andDynamics Japanese the of studies major the of one measurement, subterranean the of details some revealed has 1987) Utada, example, Evolution of the Lithosphere Project (DELP), show that since 1984 since showthat (DELP), Project Lithosphere the of Evolution subducting the that show that conductivity electrical of distribution Kashima station (KSM in fig.
Load more

Recommended publications
  • Cambridge University Press 978-1-108-44568-9 — Active Faults of the World Robert Yeats Index More Information
    Cambridge University Press 978-1-108-44568-9 — Active Faults of the World Robert Yeats Index More Information Index Abancay Deflection, 201, 204–206, 223 Allmendinger, R. W., 206 Abant, Turkey, earthquake of 1957 Ms 7.0, 286 allochthonous terranes, 26 Abdrakhmatov, K. Y., 381, 383 Alpine fault, New Zealand, 482, 486, 489–490, 493 Abercrombie, R. E., 461, 464 Alps, 245, 249 Abers, G. A., 475–477 Alquist-Priolo Act, California, 75 Abidin, H. Z., 464 Altay Range, 384–387 Abiz, Iran, fault, 318 Alteriis, G., 251 Acambay graben, Mexico, 182 Altiplano Plateau, 190, 191, 200, 204, 205, 222 Acambay, Mexico, earthquake of 1912 Ms 6.7, 181 Altunel, E., 305, 322 Accra, Ghana, earthquake of 1939 M 6.4, 235 Altyn Tagh fault, 336, 355, 358, 360, 362, 364–366, accreted terrane, 3 378 Acocella, V., 234 Alvarado, P., 210, 214 active fault front, 408 Álvarez-Marrón, J. M., 219 Adamek, S., 170 Amaziahu, Dead Sea, fault, 297 Adams, J., 52, 66, 71–73, 87, 494 Ambraseys, N. N., 226, 229–231, 234, 259, 264, 275, Adria, 249, 250 277, 286, 288–290, 292, 296, 300, 301, 311, 321, Afar Triangle and triple junction, 226, 227, 231–233, 328, 334, 339, 341, 352, 353 237 Ammon, C. J., 464 Afghan (Helmand) block, 318 Amuri, New Zealand, earthquake of 1888 Mw 7–7.3, 486 Agadir, Morocco, earthquake of 1960 Ms 5.9, 243 Amurian Plate, 389, 399 Age of Enlightenment, 239 Anatolia Plate, 263, 268, 292, 293 Agua Blanca fault, Baja California, 107 Ancash, Peru, earthquake of 1946 M 6.3 to 6.9, 201 Aguilera, J., vii, 79, 138, 189 Ancón fault, Venezuela, 166 Airy, G.
    [Show full text]
  • Title On-Land Active Thrust Faults of the Nankai‒Suruga Subduction Zone
    CORE Metadata, citation and similar papers at core.ac.uk Provided by Kyoto University Research Information Repository On-land active thrust faults of the Nankai‒Suruga subduction Title zone: The Fujikawa-kako Fault Zone, central Japan Author(s) Lin, Aiming; Iida, Kenta; Tanaka, Hideto Citation Tectonophysics (2013), 601: 1-19 Issue Date 2013-08 URL http://hdl.handle.net/2433/176993 Right © 2013 Elsevier B.V. Type Journal Article Textversion author Kyoto University *Manuscript Click here to download Manuscript: 4..Lin_Tectono_text-R1.doc Click here to view linked References 1 2 On-land active thrust faults of the Nankai-Suruga subduction 3 4 zone: the Fujikawa–kako Fault Zone, central Japan 5 6 7 8 Aiming Lin1*, Kenta Iida2, and Hideto Tanaka2 9 10 11 12 1 13 Department of Geophysics, Graduate School of Science 14 15 Kyoto University, Kyoto 606-8502, Japan 16 17 2Graduate School of Science and Technology, Shizuoka Univ., 18 19 Ohya 836, Shizuoka 422-8529, Japan 20 21 22 23 24 25 26 27 28 29 30 *Corresponding author 31 32 Dr. Aiming Lin 33 34 Department of Geophysics 35 36 Graduate School of Science 37 38 39 Kyoto University 40 41 Kyoto 606-8502, Japan 42 43 Email: [email protected] 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 1 2 Abstract 3 4 5 This paper describes the tectonic topography that characterizes recent thrusting 6 7 8 9 10 along, the on-land active fault zone of the Nankai-Suruga subduction zone, called the 11 12 13 14 Fujikawa–kako Fault Zone, located near the triple junction of the Eurasian (EUR), 15 16 17 18 Philippine Sea (PHS), and North American (NA) plates, in the western side of Mt.
    [Show full text]
  • Seismic Activities Along the Nankai Trough
    ῔ΐῑῐῒ῕ Bull. Earthq. Res. Inst. Univ. Tokyo Vol. 12 ῍,**-῎ pp. +2/ῌ+3/ Seismic Activities along the Nankai Trough Kimihiro Mochizuki+῎* and Koichiro Obana,῎ +) Earthquake Research Institute, University of Tokyo ,) Japan Marine Science and Technology Center Abstrcat Occurrences of large earthquakes with estimated magnitudes as large as 2 along the Nankai Trough have been well documented in historical materials, and the oldest documented earthquake dates back to A.D. 02.. The recurrence periods are fairly constant, and are approximately ,** years for the earthquakes occurring before +-0+, and about +** years for those after +-0+. However, the number of smaller earthquakes observed by the on-land seismic stations is very small. Both seismic and tectonic couplings along the interface between the overriding and subducting plates are estimated to be nearly +**ῌ from seismic and geodetic data. Therefore, it has been considered that relatively simple physics govern the generation of the historical large earthquakes along the Nankai Trough. With the availability of abundant information on large earthquakes and modern data sets from dense seismic and geodetic networks, the Nankai Trough is one of the best-studied seismo- genic zones. Although improvements have been seen in estimating the fault-plane parameters for the historical earthquakes, there still remain important unanswered questions, such as if there have been unidentified earthquakes that fill in the ,**-year recurrence period. Estimates of precise fault-plane parameters are being demanded to have a better understanding of earthquake genera- tion. One of the most important topics is where the updip limit of the seismogenic zone is located. The location had not been resolved by on-land seismic observations.
    [Show full text]
  • Constraints on the Moho in Japan and Kamchatka
    Tectonophysics 609 (2013) 184–201 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto Review Article Constraints on the Moho in Japan and Kamchatka Takaya Iwasaki a, Vadim Levin b,⁎, Alex Nikulin b, Takashi Iidaka a a Earthquake Research Institute, University of Tokyo, Japan b Rutgers University, NJ, USA article info abstract Article history: This review collects and systematizes in one place a variety of results which offer constraints on the depth Received 1 July 2012 and the nature of the Moho beneath the Kamchatka peninsula and the islands of Japan. We also include stud- Received in revised form 12 November 2012 ies of the Izu–Bonin volcanic arc. All results have already been published separately in a variety of venues, and Accepted 22 November 2012 the primary goal of the present review is to describe them in the same language and in comparable terms. Available online 3 December 2012 For both regions we include studies using artificial and natural seismic sources, such as refraction and reflec- tion profiling, detection and interpretation of converted-mode body waves (receiver functions), surface wave Keywords: Kamchatka dispersion studies (in Kamchatka) and tomographic imaging (in Japan). The amount of work done in Japan is Japan significantly larger than in Kamchatka, and resulting constraints on the properties of the crust and the upper- Crustal structure most mantle are more detailed. Upper-mantle structure Japan and Kamchatka display a number of similarities in their crustal structure, most notably the average Moho crustal thickness in excess of 30 km (typical of continental regions), and the generally gradational nature of the crust–mantle transition where volcanic arcs are presently active.
    [Show full text]
  • Large and Repeating Slow Slip Events in the Izu-Bonin Arc from Space
    LARGE AND REPEATING SLOW SLIP EVENTS IN THE IZU-BONIN ARC FROM SPACE GEODETIC DATA （伊豆小笠原弧における巨大スロー地震および繰り返し スロー地震の宇宙測地学的研究） by Deasy Arisa Department of Natural History Sciences Graduate School of Science, Hokkaido University September, 2016 Abstract The Izu-Bonin arc lies along the convergent boundary where the Pacific Plate subducts beneath the Philippine Sea Plate. In the first half of my three-year doctoral course, I focused on the slow deformation on the Izu Islands, and later in the second half, I focused on the slow deformation on the Bonin Islands. The first half of the study, described in Chapter V, is published as a paper, "Transient crustal movement in the northern Izu–Bonin arc starting in 2004: A large slow slip event or a slow back-arc rifting event?". Horizontal velocities of continuous Global Navigation Satellite System (GNSS) stations on the Izu Islands move eastward by up to ~1 cm/year relative to the stable part of the Philippine Sea Plate suggesting active back-arc rifting behind the northern part of the arc. We confirmed the eastward movement of the Izu Islands explained by Nishimura (2011), and later discussed the sudden accelerated movement in the Izu Islands detected to have occurred in the middle of 2004. I mainly discussed this acceleration and make further analysis to find out the possible cause of this acceleration. Here I report that such transient eastward acceleration, starting in the middle of 2004, resulted in ~3 cm extra movements in three years. I compare three different mechanisms possibly responsible for this transient movement, i.e. (1) postseismic movement of the 2004 September earthquake sequence off the Kii Peninsula far to the west, (2) a temporary activation of the back-arc rifting to the west dynamically triggered by seismic waves from a nearby earthquake, and (3) a large slow slip event in the Izu-Bonin Trench to the east.
    [Show full text]
  • The Sub-Crustal Stress Field in the Taiwan Region
    Terr. Atmos. Ocean. Sci., Vol. 26, No. 3, 261-268, June 2015 doi: 10.3319/TAO.2014.12.04.01(T) The Sub-Crustal Stress Field in the Taiwan Region Robert Tenzer1, * and Mehdi Eshagh 2 1 The Key Laboratory of Geospace Environment and Geodesy, School of Geodesy and Geomatics, Wuhan University, Wuhan, China 2 Department of Engineering Science, University West, Trollhättan, Sweden Received 22 May 2014, revised 3 December 2014, accepted 4 December 2014 ABSTRACT We investigate the sub-crustal stress in the Taiwan region. A tectonic configuration in this region is dominated by a col- lision between the Philippine oceanic plate and the Eurasian continental margin. The horizontal components of the sub-crustal stress are computed based on the modified Runcorn’s formulae in terms of the stress function with a subsequent numerical differentiation. This modification increases the (degree-dependent) convergence domain of the asymptotically-convergent series and consequently allows evaluating the stress components to a spectral resolution, which is compatible with currently available global crustal models. Moreover, the solution to the Vening Meinesz-Moritz’s (VMM) inverse isostasy problem is explicitly incorporated in the stress function definition. The sub-crustal stress is then computed for a variable Moho geometry, instead of assuming only a constant Moho depth. The regional results reveal that the Philippine plate subduction underneath the Eurasian continental margin generates the shear sub-crustal stress along the Ryukyu Trench. Some stress anomalies asso- ciated with this subduction are also detected along both sides of the Okinawa Trough. A tensional stress along this divergent tectonic plate boundary is attributed to a back-arc rifting.
    [Show full text]
  • Philippine Sea Plate Inception, Evolution, and Consumption with Special Emphasis on the Early Stages of Izu-Bonin-Mariana Subduction Lallemand
    Progress in Earth and Planetary Science Philippine Sea Plate inception, evolution, and consumption with special emphasis on the early stages of Izu-Bonin-Mariana subduction Lallemand Lallemand Progress in Earth and Planetary Science (2016) 3:15 DOI 10.1186/s40645-016-0085-6 Lallemand Progress in Earth and Planetary Science (2016) 3:15 Progress in Earth and DOI 10.1186/s40645-016-0085-6 Planetary Science REVIEW Open Access Philippine Sea Plate inception, evolution, and consumption with special emphasis on the early stages of Izu-Bonin-Mariana subduction Serge Lallemand1,2 Abstract We compiled the most relevant data acquired throughout the Philippine Sea Plate (PSP) from the early expeditions to the most recent. We also analyzed the various explanatory models in light of this updated dataset. The following main conclusions are discussed in this study. (1) The Izanagi slab detachment beneath the East Asia margin around 60–55 Ma likely triggered the Oki-Daito plume occurrence, Mesozoic proto-PSP splitting, shortening and then failure across the paleo-transform boundary between the proto-PSP and the Pacific Plate, Izu-Bonin-Mariana subduction initiation and ultimately PSP inception. (2) The initial splitting phase of the composite proto-PSP under the plume influence at ∼54–48 Ma led to the formation of the long-lived West Philippine Basin and short-lived oceanic basins, part of whose crust has been ambiguously called “fore-arc basalts” (FABs). (3) Shortening across the paleo-transform boundary evolved into thrusting within the Pacific Plate at ∼52–50 Ma, allowing it to subduct beneath the newly formed PSP, which was composed of an alternance of thick Mesozoic terranes and thin oceanic lithosphere.
    [Show full text]
  • Temporal Evolution of Fault Coupling Associated with the Occurrence of Slow Slip Events in Central Japan
    Temporal evolution of fault coupling associated with the occurrence of slow slip events in central Japan Lucile Bruhat∗y1 and Junichi Fukuda2 1Laboratoire de G´eologiede l'ENS { CNRS : UMR8538 { France 2Earthquake Research Institute { Japan Abstract Although interseismic coupling has often been considered to be stationary in time, there is increasing evidence that fault locking can vary both spatially and temporally during the interseismic period. The detection of transient slip behavior in the proximity of locked regions, such as slow slip events or decadal-scale uncoupling events, suggest in fact that the notion of a characteristic interseismic coupling distribution might not be appropriate. This study focuses on interseismic deformation rates in the southeastern part of the Kant¯o area in Japan. This region lies at junction of two subduction zones, leading to a particularly complicated tectonic setting. On the Eastern side, the Pacific plate subducts under the Okhotsk Plate at the Japan Trench, while the Sagami Trough to the south evidences the subduction of the Philippine Sea Plate under the Okhotsk Plate. The Philippine Sea Plate interface has hosted M8 megathrust earthquakes in the vicinity of Tokyo metropolitan area, such as the 1923 Great Kant¯oearthquake. Studies of interseismic deformation rates [Sagiya, (2004); Nishimura et al. (2007)] have shown that these megathrust events are consistent with the presence of a strongly locked asperity on the western extent of the Philippine Sea Plate interface at depths above 15-20km. Meanwhile, offshore the B¯os¯oPeninsula, i.e. on the eastern side of the interface, recurrent slow slip events have been detected in 1996, 2002, 2007, 2011, 2013-2014, and 2018.
    [Show full text]
  • Tsunami Deposits and Earthquake Recurrence Along the Nankai
    Tsunami deposits and earthquake recurrence along the Nankai, Suruga and Sagami Troughs OSAMU FUJIWARA1 and JUNKO KOMATSUBARA1 1: Active Fault Research Center, AIST, C7, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan ([email protected]) INTRODUCTION Histories of great (M~8) subduction-zone earthquakes inferred from tsunami deposits span 3000 years for the Nankai and Suruga Troughs and nearly 10,000 years for the Sagami Trough. The inferred histories contain variable recurrence intervals. The shortest recurrence intervals, 100-200 years for the Nankai Trough and 150-300 years for the Sagami Trough, are similar to those known from written earthquake and tsunami records in the last 1300 years. Longer intervals inferred from the tsunami deposits probably reflect variability in rupture mode, incompleteness of geologic records, and insufficient research. 130E 140E GEOLOGICAL SETTING The Nankai, Suruga and Sagami Troughs comprising the northeastern subduction margin of the Philippine Sea plate are 40N seismically active areas in the world. The Philippine Sea plate converges with overriding plates at a rate of 49-42 mm/year along the Nankai Trough and 27 mm/year around the Sagami Trough (Seno et al., 1993, 1994). Several source areas (segments) 35N Japan are located along these troughs, each of which are 100 - 150 km long along the trough axis and potentially excites M8-class Trench earthquake accompanied by large tsunami and coastal uplift or subsidence. Earthquakes and tsunamis occurred from these areas have repeatedly damaged the Pacific coast of Japan, including Tokyo Nankai Trough and Osaka metropolitan areas. Trench Trench Izu-Ogasawara Izu-Ogasawara Fig.
    [Show full text]
  • Interplate Coupling Along the Central Ryukyu Trench Inferred from GPS/Acoustic
    Interplate coupling along the central Ryukyu Trench inferred from GPS/acoustic seafloor geodetic observation Mamoru Nakamura University of the Ryukyus The Ryukyu trench is a major convergent plate boundary where the Philippine Sea plate is subducting at a rate of about 8 cm/yr. Large earthquakes have not been reported along the Ryukyu subduction for the last 300 years. Because the rate of release of seismic moment in the Ryukyu Trench over the last 80 years is 5% in consideration of the plate convergence rate, interseismic coupling in the trench is assumed to be weak.The GPS measurements by Japan Geographical Survey Institute also show the southward motion of Ryukyu arc, which is due to extensional rifting of Okinawa Trough. Backslip by the interplate coupling between the subducting Philippine Sea plate and the overriding Eurasian plate cannot have been detected in the GPS network along the Ryukyu Islands. We have started the GPS/acoustic seafloor observation to detect the inter-plate coupling in the central Ryukyu trench. For this measurement, we used a system capable of performing two main tasks: precise acoustic ranging between a ship station (observation vessel) and seafloor transponders, and kinematic GPS positioning of observation vessels. The seafloor reference point was set at about 33 km landward from the axis of the Ryukyu trench (southeast of Okinawa Island). A set of three acoustic transponders has been installed on the seafloor, at a depth of about 2900m. The transponders are placed to form a triangular. Five campaign observations were carried out for the period from January 2008 to November 2009.
    [Show full text]
  • Origin of Marginal Basins of the NW Pacific and Their Plate Tectonic
    Earth-Science Reviews 130 (2014) 154–196 Contents lists available at ScienceDirect Earth-Science Reviews journal homepage: www.elsevier.com/locate/earscirev Origin of marginal basins of the NW Pacificandtheirplate tectonic reconstructions Junyuan Xu a,⁎, Zvi Ben-Avraham b,TomKeltyc, Ho-Shing Yu d a Department of Petroleum Geology, China University of Geosciences, Wuhan, 430074, China. b Department of Geophysics and Planetary Sciences, Tel Aviv University, Ramat Aviv 69978, Israel c Department of Geological Sciences, California State University, Long Beach, CA 90840, USA d Institute of Oceanography, National Taiwan University, Taipei, Taiwan article info abstract Article history: Geometry of basins can indicate their tectonic origin whether they are small or large. The basins of Bohai Gulf, Received 4 March 2013 South China Sea, East China Sea, Japan Sea, Andaman Sea, Okhotsk Sea and Bering Sea have typical geometry Accepted 3 October 2013 of dextral pull-apart. The Java, Makassar, Celebes and Sulu Seas basins together with grabens in Borneo also com- Available online 16 October 2013 prise a local dextral, transform-margin type basin system similar to the central and southern parts of the Shanxi Basin in geometry. The overall configuration of the Philippine Sea resembles a typical sinistral transpressional Keywords: “pop-up” structure. These marginal basins except the Philippine Sea basin generally have similar (or compatible) Marginal basins of the NW Pacific Dextral pull-apart rift history in the Cenozoic, but there do be some differences in the rifting history between major basins or their Sinistral transpressional pop-up sub-basins due to local differences in tectonic settings. Rifting kinematics of each of these marginal basins can be Uplift of Tibetan Plateau explained by dextral pull-apart or transtension.
    [Show full text]
  • Seismotectonic Modeling of the Repeating M 7-Class Disastrous Odawara Earthquake in the Izu Collision Zone, Central Japan
    Earth Planets Space, 56, 843–858, 2004 Seismotectonic modeling of the repeating M 7-class disastrous Odawara earthquake in the Izu collision zone, central Japan Katsuhiko Ishibashi Research Center for Urban Safety and Security/Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501, Japan (Received February 16, 2004; Revised July 15, 2004; Accepted July 21, 2004) Odawara City in central Japan, in the northernmost margin of the Philippine Sea (PHS) plate, suffered from severe earthquake disasters five times during the last 400 years with a mean repeat time of 73 years; in 1633, 1703, 1782, 1853 and 1923. In this region, non-volcanic Izu outer arc (IOA), the easternmost part of the PHS plate, has been subducted beneath Honshu (Japanese main island), and volcanic Izu inner arc (IIA) on the west of IOA has made multiple collision against Honshu. I hypothesize ‘West-Sagami-Bay Fracture’ (WSBF) beneath Odawara, a north-south striking tear fault within the PHS plate that has separated the descending IOA crust from the buoyant IIA crust, through examinations of multiple collision process and the PHS plate configuration. WSBF is considered a blind causative fault of the 1633, 1782 and 1853 M 7 Odawara earthquakes, and is inferred to have ruptured also during the 1703 and 1923 great Kanto earthquakes simultaneously with the interplate main fault. A presumable asperity on WSBF just beneath Odawara seems to control the temporal regularity of earthquake occurrence. Though WSBF has not yet been detected directly, it is considered an essential tectonic element in this region, which might be a fracture zone with a few or several kilometer thickness actually.
    [Show full text]