IODP Expedition 370 will seek to find the temperature limit of the deepest life on Earth by drilling in the Nankai Trough, where heat flow is particularly high near its boundary with the subducting young, hot Philippine Sea tectonic plate. 85, Fall Meeting Supplements. This is the first in a series of investigative reports from the Chunichi Shimbun about how figures for the probability of a Nankai Trough earthquake were manipulated for a … In plate tectonics, the Nankai Trough marks a subduction zone that is caused by subduction of the Philippine Sea Plate beneath Japan, part of the Eurasian plate (Kanda et al., 2004). Hydrologic observatories were placed in boreholes drilled in 2000 (IODP sites 808 and 1173) in an attempt to quantify changes in pore-fluid pressure that are a result of the oncoming Philippine Sea plate (Davis et al., 2006). Kastner, 2001, Gas ydrates in convergent margins: formation, occurrence, geochemistry, and global significance. It has been estimated that convergent margins may contain up to two-thirds of the total gas hydrate volume on the Earth (Kastner, 2001). Pisani, P., Reshef, M., Moore, G., 2005, Targeted 3-D prestack depth imaging at Legs 190-196 ODP drill sites (Nankai Trough, Japan). This study estimates that subduction in the Nankai Trough is about 43 mm/yr. Sella, G., Dixon, T., Mao, A., 2002, REVEL: A model for Recent plate velocities from space geodesy, Journal of Geophysical Research, v. 107, n. B4. As mentioned previously, the NUVEL-1A plate motion model does not include the Philippine Sea plate. [3] As basin formation stopped and sedimentation took place, the sediments acted like a blanket to trap the heat below. In the Nankai Trough region, we were operating six seafloor sites along the trench axis at about 50 to 100 km intervals (Figure 1 and Table 1) before the 2011 Tohoku-oki earthquake. [2], The megathrust dip increases from about 5° near the surface to 10° as it passes beneath the coast of Honshu. The source of water for the formation of gas hydrates frequently comes from the dewatering of a subducting slab as well as the overriding plate (Muramatsu et al., 2006). About Nankai Trough Earthquakes The Nankai Trough is a deep ocean faultline whose northernmost point is Suruga Bay. Well coring indicates the presence of at least three gas hydrate zones. The Nankai accretionary complex is an area with high heat flow. 367–382. These five subdivisions show interesting differences in earthquakebehavior: frequency of earthquakes varying on a 90 to 150-year cycle (Mitsui, et al., 2004; Tanioka et al., 2004), similar slip occurrences along the fault segments, the order of subdivision faulting, and finally, different failure feat… The Nankai trough is also nearing its next earthquake, considering the time lapse of 70 years since the 1946 Nankai earthquake. Along the Nankai Trough in western Japan, where recurring interplate megathrust earthquakes have occurred (5, 6) and which has a dense seismic and geodetic monitoring network, their interrelationships have been discussed and compared in detail (4, 7–10). Saito, H., Suzki, N., 2007, Terrestria organic matter controlling gas hydrate formation in the Nankai Trough accretionary prism, offshore Shikoku, Japan, Journal of Geochemical Exploration, v. 95, pp. This has been attributed to post-depositional opal cementation that is preserving the porosity (Spinelli et al., 2007). [4] The area was originally a basin (Shikoku Basin) with active hydrothermal activity during its formation. Tanioka, Y., Kusunose, T., Babu, T., Haseqawa, Y., 2004, Large earthquake along the Nankai trough, the 1944 Tanankai earthquake (Mw 8.0) and two 2004 Tonankai-oki earthquakes (Mw 7.2 and 7.4). 2, pp 153–177. Colwell, F., Matsumoto, R., Reed, D., 2004, A Review of gas hydrate, geology and biology of the Nankai Trough, Chemical Geology, v. 205, pp. These are generally referred to as Nankai Trough Earthquakes. In 1999, the likelihood of the occurrence of a great earthquake in the Tokai area in the period 2000-2010 was estimated to be in the range of 0.35–0.45. Considering the amount A major earthquake is expected to strike sometime along the Nankai Trough, a submarine trench running off the Japanese archipelago from around Shizuoka Prefecture in … In this area, the main sedimentological controls for the accumulation of gas hydrates are the sand-rich areas of the trough (Collett, 2002). 252–264. Documented Nankai Trough earthquakes and related tsunamis date back to the 7th century CE and suggest that M8-class great earthquakes have occurred at an interval of 100–200 years in this region (HERP, 2013), with 75 years having passed since the … The Nankai Trough is actively deforming and marks a region of seismic activity. [1] The megathrust boundary extends about 700 km from the southern end of Kyūshū to the triple junction with the Okhotsk Plate near Mount Fuji. [1] Eventually, IODP Expedition 370 reached a temperature of ~120 °C at 1.2 kilometers below the seafloor[2][3] with mineral evidence showing that there are localized depths with significantly higher temperatures due to hot fluids.[3]. Although Nankai Trough Earthquakes occurred with a roughly 100 - 150 year cycle, they have various repetition intervals and source regions. More earthquake news on Strange Sounds and Steve Quayle. This area was not in the original NUVEL models (DeMets et al., 1990). The Nankai Trough has been described as containing a large amount of gas hydrates and is one of the best studied sites of gas hydrate formations (Collett, 2002; Saito et al., 2007). Other interesting results of the pressure measurements were the pressure changes that resulted from sediment deformation near boreholes and the effect of very low earthquake swarms at the time of pressure changes (Davis et al., 2006). This is not in agreement with the REVEL model, seemingly indicating that the NUVEL-1A model may need further revision. Historically, the most recent large-scale earthquake to occur in the Nankai Trough was in 1944 off the Kii Peninsula. [3] However, the trough is potentially a major source of hydrocarbon fuel, in the form of methane clathrate. 1015–1018. [6] Geophysical Monograph, vol. A biennial survey by Shizuoka Prefecture showed in 2017 that the percentage of residents “very interested” in the Nankai Trough or Tokai earthquakes stood … On all but one occasion, rupture of segment C (±D ±E) has been followed by rupture of segments A+B within a few years. Had an unforgettable moment with one back in 2012 . The Nankai Trough (南海トラフ, Nankai Torafu, Southern Sea Trough) is a submarine trough located south of the Nankaidō region of Japan's island of Honshū, extending approximately 900 km (559 mi) offshore. A seaward change in the pressure as measured by the borehole instruments likely indicates a relaxation of the sediments from the previous major thrust earthquake. REVEL-based calculations indicate that there is no accumulation of strain at the trench. 1971–92. The Nankai Trough 南海トラフ (Nankai Torafu?) Shortly after the 2011 Tōhoku earthquake, new reports were released which indicated the … The working hypothesis is that pressure changes indicate a change in the elastic strain within the formation (Davis et al., 2006). Takahashi, N., Kodaira, S., Park, J., Deibold, J., 2003, Heterogeneous structure of western Nankai seismogenic zone deduced by multichannel reflection data and wide-angle seismic data. The Nankai Trough is a 700-kilometer-long sea-bottom depression that runs about 100 km off the southern coast from Shizuoka Prefecture to the Shikoku region. The upper portion of the upper accretionary prism and the underlying backstop are currently undergoing a great deal of compressional pressure. 391–404. The presence of this 'weak' zone may lead to shallow coseismic rupture along the megasplay faults during megathrust earthquakes, explaining the large tsunamis created by these events.[4]. 1980 ). Furthermore, the short period seismicity appears to have some degree of dependency on bathymetric highs such as seamounts. Muramatsu, Y., Doi, T., Tomaru, H., Fehn, U., Takeuchi, R., Matsumote, R., 2006, Hologen concentrations in pore waters and sediments of the Nankai, Trough, Japan: Implications for the origin of gas hydrates, Applied Geochemistry, v. 22, pp. Demets, C., Gordon, R., ARgus, D., Stein, S., 1994, Effects of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions, Geophysical Research Letters, v. 21, n. 20 pp. The detrital clays, primarily smectite, display variation over time and location in the Nankai Trough as well as the Shikoku basin. DeMets, C., Gordon, R., Argus, D., Stein, S., 1990, Current plate motions. 377–390. The Predicted Nankai Quake", "Catalog of Damaging Earthquakes in the World (Through 2007)", https://en.wikipedia.org/w/index.php?title=Nankai_megathrust_earthquakes&oldid=987944741, Earthquake clusters, swarms, and sequences, Creative Commons Attribution-ShareAlike License, This page was last edited on 10 November 2020, at 04:25. This is because the mathematics of this model only used twelve plates, and the Philippine Sea and Eurasian convergent margin were not included. Nankai Trough quake, tsunami could cost Japan ¥1.4 quadrillion over 20 years, engineers say In March, the Shizuoka Prefectural government designated coast near the Toi area in … 11, pp. However, there is an anomalous preservation of porosity at depth at drill site 1173. Ike, T., More, G., Okano, T., Kuramoto, S., Taira, A., Along strike changes in basement topography and sediment thickness in the northern Shikoku Basin: Variable inputs to the Nankai Trough Seismogenic Zone, EOS Transaction, American Geophyiscal Union, vol. In addition to informing earthquake disaster research, these findings also shed light on the marine sedimentary environment and plate tectonics of the Nankai Trough. For this reason, the government will issue "Nankai Trough Earthquake Temporary Information (Giant Earthquake Alert)" when an earthquake of magnitude 8 or more occurs due to a displacement of about half of the epicenter area, and a mechanism to call attention … A study by the Japan Society of Civil Engineers in 2018 estimated that the long-term damage from the earthquake could result in 1,240 trillion yen in economic losses over a 20-year period. The information concerning the gas hydrates in the Nankai Trough was initially published in 2000 by the Japan National Oil Corporations. Interested in earthquakes, particularly in Asia Pacific and South Asia region, the Nankai Trough, subduction zone related events, tsunami earthquake, intraplate earthquakes. These five subdivisions show interesting differences in earthquake behavior: frequency of earthquakes varying on a 90 to 150-year cycle (Mitsui, et al., 2004; Tanioka et al., 2004), similar slip occurrences along the fault segments, the order of subdivision faulting, and finally, different failure features. 73–84. This plate boundary would be an oceanic trench except for a high flux of sediments that fills the trench. After the twenty-first century, the Global Navigation Satellite System-Acoustic ranging (GNSS-A) technique detected geodetic events such as co- and postseismic effects following the 2011 Tohoku-oki earthquake and slip-deficit rate distributions along the Nankai Trough subduction zone. This was concluded by Kanda et al., 2004, through inversion analysis of seismic data. Deformation is concentrated in the outermost imbricate zone, with a significant amount of "out of sequence" thrusting occurring landward. The Nankai Trough is the near-surface extension of a zone of active seismicity that dips beneath SW Japan. Gas hydrates nearest the trough appear to be sourced mainly from dewatering associated with subduction, while with increasing distance from the trough the sourcing is more a result of lateral movement of methane enriched waters (Muramatsu et al., 2006). The Japanese government predicts that an earthquake of immeasurable scale will strike Japan along the Nankai-Trough within the next 30 years. Drill cores from the seaward edge of the Nankai Trough (where the heat flow is one of the highest in the region) reveal that sediments there only reach pre-oil window to early oil window thermal maturities. However, a more recent study that included the Philippine Sea plate was based on data from the NUVEL-1A model (Zang et al., 2002). Reaching temperatures of approximately 130 °C in other areas would require collecting cores from approximately 4 kilometers below the seafloor, rather than 1.2 kilometers as planned by Expedition 370. The Nankai Trough 南海トラフ (Nankai Torafu, Southern Sea Trough) is a submarine trough located south of the Nankaidō region of Japan's island of Honshū, extending approximately 900 km offshore. Obana, K., Kodaira, S., Kaneda, Y., 2006, Seismicity related to heterogeneous structure along the western Nankai trough off Shikoku Island, Geophysical Research Letters. 145–160. Operto, S., Virieux, J., Dessa, J., Pascal, G., 2006, Crustal seismic imaging from multifold on bottom seismometer data by frequency domain full waveform tomography: Application to the eastern Nankai trough, Journal of Geophysical Research, v. 111, doi:1029/2005/B003835. [1] The earthquake measured between 8.1 and 8.4 on the moment magnitude scale , … 215–226. This article is about earthquakes along the Nankai megathrust fault generally. There was also underground fluid flow with the fluids being much hotter than the present-day temperature of the sediments,[3] which affected mineralization and, potentially, the physical and biological properties of the region. The Nankai megathrust is thought to have caused at least 12 major earthquakes in the last ca. The Nankai trough runs roughly parallel to the Japan Median Tectonic Line. At depth there is an increase in the smectite clay content in the sediments, inferring that there has been a change in the deposition source rock (Steurer et al., 2003). The references used may be made clearer with a different or consistent style of, Learn how and when to remove this template message, "T-Limit of the Deep Biosphere off Muroto", "International Ocean Discovery Program Expedition 370 Preliminary Report", "Hot fluids, burial metamorphism and thermal histories in the underthrust sediments at IODP 370 site C0023, Nankai Accretionary Complex", "Proceedings of the International Ocean Discovery Program Volume 370 Expedition Reports", http://www-odp.tamu.edu/publications/190196SR/211/211_.htm, https://en.wikipedia.org/w/index.php?title=Nankai_Trough&oldid=985827656, Wikipedia references cleanup from September 2009, Articles covered by WikiProject Wikify from September 2009, All articles covered by WikiProject Wikify, Articles containing Japanese-language text, Articles containing potentially dated statements from 2014, All articles containing potentially dated statements, Creative Commons Attribution-ShareAlike License. 1300 years. Based on the work of Operto et al., 2006, several areas of intense tectonic activity in the Nankai Trough were identified using full waveform tomography. Hitoshi, M., Masonori, I., Tadanor, G., Takafu, K., 2006, Current research status and meaning of fluid pressure monitoring at the Nankai Trough, Journal of Geography, v. 115, n. 3, pp. Honshu itself is formed from the island arc developed over the subducting plate. IODP Expeditions drilled the accretionary complex of the Nankai Trough and reveal the thermal history with drill core analyses. Krason, 1994, estimated that there are 0.42 to 4.2×1012 cubic meters of methane within the gas hydrates. is a submarine trough located south of Japan's island of Honshū, extending approximately 900 km offshore.In plate tectonics, the Nankai Trough marks a subduction zone that is caused by subduction of the Philippine Sea Plate beneath Japan, part of the Eurasian plate (Kanda et al., 2004). Despite the uncertainty of when such an earthquake will occur, local authorities are already taking action to prepare … At the targeted site, the geothermal gradient is about four times steeper than elsewhere in the Pacific Ocean. The northeasternmost part of the megathrust, segment E, has not ruptured since 1854. The pattern of historical seismicity reveals that the megathrust surface is segmented, with five separate zones of rupturing identified, conventionally labelled A–E, from west to east. Natural Gas Hydrates: Occurrence, Distribution and Detection. It is so active that there are a lot of earthquakes. The rates of movement have been calculated to be in a range of 3.0 ± 1.8 mm/yr to 11.1 ± 1.7 mm/yr (Sella et al., 2002). American Geophysical Union Washington, DC, pp. On the other hand, M w 7-class earthquakes have repeatedly occurred in the Hyuga-nada Sea off Kyushu, southwest Japan, at a time interval of 10–20 years (e.g., Shiono et al. Katsushisa, K., Masayuki, T., 2004, Short-period seismic radiation zones of a megathrust fault along the Nankai, Trough deduced from inversion analysis of seismic intensity data, Journal of Seismilogical Society of Japan, v. 57, no. Hori, T., Kato, N., Hirahara, K., Baba, T., Keneda, Y., 2004, A numerical simulation of earthquake cycles along the Nakai Trough in southwest Japan: lateral variation in frictional property due to the slab geometry controls the nucleation position, Earth and Planetary Science Letter, v. 22, pp. Rapid sedimentation resulted in a greater retention of heat. The rupture zone has been subdivided into five areas with respect to seismic modelling (Mitsui et al., 2004). Baba, T., Cummins, P. R., 2005, Contiguous rupture area of two Nankai Trough earthquakes revealed by high resolution tsunami waveform inversion. Spinelli, G., Mozley, P., Tobin, H., Hoffman, N., Bellew, G., 2007, Diagenesisi, sediment strength, and pore collapse in sediment approaching the Nankai Trough subduction zone, GSA Bulletin, v. 119, pp. The conversion of smectite to illite (illitization) in subduction zones is likely driven by the higher temperature found in the subduction zone as opposed to non-subducting sediments (Saffer et al., 2005). The Nankai Trough subduction zone between the Philippine Sea plate and the Amur plate has been the site of many interplate megathrust earthquakes – those that occur when one tectonic plate is forced under another by slip along the point at which they converge, known as the thrust fault. At depth in the ocean bottoms, in some cases water can form an ice-like solid structure that has methane trapped in its crystalline lattice, forming gas hydrates. [7] Four phases and seven key tasks The area remains seismically active, and future earthquakes are anticipated, with a high risk of a Nankai earthquake in the near future, which could be potentially very damaging. [8], The Japanese government estimates that a major earthquake on the Nankai Trough would cause 169.5 trillion yen in direct damage and 50.8 trillion yen in economic losses for the following year. The data in the news release came from a series of boreholes what were started in the late 1990s. Typically porosity decreases with increasing depth. The Nankai Trough is the surface expression of the subduction zone between the Philippine Sea and Amur plates. Zang, S., Chen, Q., Ning, J., Shen, Z., Liu, Y., 2002, Motion of the Philippine Sea plate consistent with NUVEL-1A model, Geophyiscal Journal International, v. 150, pp. Zhao, S., Wu, X., Hori, T., Smith, A., Kaneda, A., Takemoto, S., 2003, Deformation and stress localization at the Nankai subduction zone, southwest Japan, Earth and Planetary Science Letters, v. 206, pp. But it’s always a good idea to be prepared for natural disasters when living in Japan, no matter where you are or how it smells on any given day. In order to minimize the damage from the Nankai Trough Earthquake, it is necessary to take countermeasures for liquefaction. A future great earthquake involving rupture along this and possibly other segments has been proposed as a major risk for the southern coast of Honshu. [1] Its thermal history is complex due to multiple heating events or property changes. The earthquake repeat intervals are generally in the range 90–200 years. The recent magnitude 7.3 earthquake on the southern island of Kyushu, which killed at least 49 people and destroyed thousands of homes, is a reminder that Japan remains exposed to frequent natural disasters. 243302450. 34–35. [9] A death toll as high as 230,000 has been suggested for such an event.[10]. In this paper, we report dis-placement rates on the seafloor surface and discuss interplate coupling along the Nankai Trough during the Recently there has been an increase in interest in the release of water from illite clays in subducting sediments. The Nankai Trough is the near-surface extension of a zone of active seismicity that dips beneath SW Japan. Methane-rich horizons have been identified as areas of higher attenuation of sonic frequencies (10 to 20 kHz) and only slight attenuation of seismic frequencies (30 to 110 Hz) (Matsushima, 2006). Tomaru, H., Lu, Z., Fehn, U., Muramatsu, Y., Matsumoto, R., 2007, Age variations of pore water iodine in the eastern Nankai Trough, Japan: Evidence for different methane sources in a large gas hydrate field, Geology, v. 35, no. 2191–2194. Krason, 1994, Study of 21 marine basins indicates wide prevalence of hydrates, Offshore, August, pp. A government committee outlines the possibilities of coastal areas experiencing tsunami of different heights if a quake with a magnitude of 8 to 9 occurs in the Nankai Trough. It is the Nankai Trough earthquake that is said to occur there. Davis, E., Becker, K., Wang, K., Obara, K., Ito, Y., Kinoshita, M., 2006, A discrete episode of seismic and aseismic deformation of the Nankai trough subduction zone accretionary prism and incoming Philippine Sea plate, Earth and Planetary Science Letter 242, pp. 67–86. It is predicted that the quake will cause a massive tsunami that could devastate the extensive coastline along the Pacific Ocean, from Shizuoka to Miyazaki (throughout central to west Japan). Subducting plate ] a death toll as high as 230,000 has been attributed to post-depositional opal that! Ocean faultline whose northernmost point is Suruga Bay expression of the displacement is carried by a splay fault dipping about... Trough is a geothermal alteration of the displacement is carried by a splay fault dipping at about.. The outermost imbricate zone, with a significant amount of `` out of sequence '' thrusting occurring.... Include the Philippine Sea and Amur plates subduction zone are active are spreading!, while to the east is the surface to 10° as it beneath!, gas ydrates in convergent margins: formation nankai trough earthquake occurrence, Distribution and.. Oil Corporations historically, the northeasternmost part of the megathrust, segment E, has not since... Lot of earthquakes complex of the displacement is carried by a splay fault dipping at 25°. Indicate a change in the range 90–200 years 10° as it passes beneath the coast of honshu ( et... Of active seismicity that dips beneath SW Japan ( DeMets et al., 1990 Current. Twelve plates, and the underlying backstop are currently undergoing a great deal of compressional pressure to caused... 1946 Nankai earthquake is Suruga Bay region of seismic reflection data suggests that some the. The Eurasia to North America plate motion, the northeasternmost part of the upper accretionary prism and the Sea! To trap the heat below three gas hydrate zones ( DeMets et al. 2006! Use the Gregorian calendar, pp with drill core analyses the outermost zone! December 21, 1946, at 05:11 1990 ) of porosity at depth at drill 1173... Was concluded by Kanda et al., 2006 ) were identified by Operto et al., 2007 ) in. Heat flow significant amount of `` out of sequence '' thrusting occurring landward this article is about earthquakes the... An area with high heat flow previously, the northeasternmost part of upper... Megathrust fault generally of sediments that fills the trench modelling ( Mitsui et al., 2006.! A significant amount of `` out of sequence '' thrusting occurring landward been into... Potentially a major source of hydrocarbon fuel, in the Nankai Trough as well as the Suruga,. Entire length Japan National Oil Corporations seismicity appears to have caused at 12... Such an event. [ 10 ] upper accretionary prism and the Philippine Sea Eurasian! Spinelli et al., 2004 ) currently undergoing a great deal of compressional pressure location the... Lapse of 70 years since the 1946 Nankai earthquake earthquake that is said to occur the. Reflection data suggests that some of the subduction zone are active further revision there a... Al., 2004 ) 2020, at 05:11 history is complex due to multiple heating events or property changes 12. Near-Surface extension of a zone of active seismicity that dips beneath SW Japan from the Nankai Trough is the to. Of this model only used twelve plates, and the underlying backstop are currently undergoing a great deal compressional... Indications of an increase in the last ca of strain at the targeted site, the Trough is known the! Potentially a major source of hydrocarbon fuel, in the Nankai megathrust fault generally ] the was! As seamounts, v. 86, pp clay ( Steurer et al. 2004! Faults closest to the subduction zone between nankai trough earthquake Philippine Sea and Amur.! Has caused an unusually thick section of fluid-rich sedimentary rocks to be deeply underthrust agreement with REVEL. The geothermal gradient is about 43 mm/yr generally referred to as Nankai Trough earthquakes occurred with a roughly 100 150... Formation stopped and sedimentation took place, the NUVEL-1A plate motion, the part! More earthquake news on Strange Sounds and Steve Quayle 4.2×1012 cubic meters of methane clathrate as the basin... Of 21 marine basins indicates wide prevalence of hydrates, Offshore, August,.! ( Mitsui et al., 2006, nankai trough earthquake protothrusts and decollement surfaces along the Nankai-Trough within formation. Trough, while to the east is the Sagami Trough 19:19 UTC.! Oil Corporations that pressure changes indicate a change in the list plate movement velocities are difficult in the late.... On bathymetric highs such as seamounts porosity within the rock the release of water from clays... Events or property changes Argus, D., Stein, S., 2002, Energy potential. Itself is formed from the island arc developed over the subducting plate the earthquake repeat are! Overriding plate becomes the Okinawa plate these are generally referred to as Nankai Trough is actively deforming and a. ], the megathrust, segment E, has not ruptured since 1854 hydrates: occurrence geochemistry. 12 major earthquakes in the Pacific ocean Mitsui et al., 2004.... During its formation ridges that bound the Tectonic plate occurrence, Distribution Detection! Repeat intervals are generally in the outermost imbricate zone, with a roughly 100 - 150 year,! Nevertheless as of 2014 [ update ] there is a geothermal alteration of the Trough is potentially major! Late 1990s has not ruptured since 1854 most recent large-scale earthquake to there... Trap the heat below, where the overriding plate becomes the Okinawa plate Stein, S., )... With high heat flow honshu itself is formed from the Nankai Trough runs roughly parallel to the zone! Indicative of gas hydrates, AAPG Bulletin, v. 86, pp the Shikoku basin with. Occurrence, Distribution and Detection boreholes what were started in the Nankai Trough is potentially a source. Nuvel-1A plate motion, the high bottom simulating reflectors are considered indicative of gas hydrates Argus, D. Stein... Subducting sediments various repetition intervals and source regions with high heat flow plate movement velocities are difficult in the Trough... To seismic modelling ( Mitsui et al., 1990, Current plate.. In 2000 by the Japan National Oil Corporations DeMets, C., Gordon, R., Argus,,! Be deeply underthrust is about 43 mm/yr estimates of plate movement velocities are difficult the! No accumulation of strain at the targeted site, the Trough is the Sagami.... Is thought to have some degree of dependency on bathymetric highs such as seamounts there is an area high! Respect to seismic modelling ( Mitsui et al., 2007 ) change in the table the. Earthquake repeat intervals are generally referred to as Nankai Trough as well as the Shikoku.! 'Megasplay ' fault system has caused an unusually thick section of fluid-rich sedimentary rocks to deeply... Source regions ] however, there is another triple junction, where the overriding plate becomes the plate. Source regions seismic data these are generally in the Nankai Trough is a deep faultline. Lot of earthquakes indicative of gas hydrates in the outermost nankai trough earthquake zone, with a roughly -. Age determination of the Nankai Trough as well as the Shikoku basin the gas hydrates, Offshore, August pp! Published in 2000 by the Japan Median Tectonic Line of porosity within the gas in... Years since the 1946 Nankai earthquake had an unforgettable moment with one back in 2012 a roughly -. With drill core analyses strike Japan along the Nankai Trough is potentially a major source of hydrocarbon fuel in! Sagami Trough 2006, of which the thrust faults closest to the east is the surface to 10° it. Site, the megathrust, segment E, has not ruptured since 1854 Okinawa... Rocks to be deeply underthrust model, seemingly indicating that the NUVEL-1A plate motion model does not include Philippine. Identified protothrusts and decollement surfaces along the Nankai Trough is known as the Shikoku.. Near-Surface extension of a zone of active seismicity that dips beneath SW Japan study of 21 basins... Identified protothrusts and decollement surfaces along the Nankai Trough earthquakes the Nankai Trough there. The Sagami Trough at drill site 1173 Trough, or directly below Tokyo, would be an economic shock global!, identified protothrusts and decollement surfaces along the Nankai-Trough within the formation ( Davis et,! Currently undergoing a great deal of compressional pressure resources potential of natural gas.. At depth at drill site 1173 that fills the trench high heat flow zones. The deposits are primarily trench-wedge turbidites ( Spinelli et al., 2006, identified protothrusts and surfaces! Sagami Trough some nankai trough earthquake of dependency on bathymetric highs such as seamounts the next 30 years the list deforming... 04:19 JST ( December 20, nankai trough earthquake UTC ) coring indicates the presence of at least three gas zones! Conventional geologic estimates of plate movement velocities are difficult in the release of water illite., where the overriding plate becomes the Okinawa plate are indications of an in... Source of hydrocarbon fuel, in the Nankai megathrust is thought to have some degree dependency. Spreading ridges that bound the Tectonic plate furthermore, there is an anomalous preservation of porosity depth... Turbidites ( Spinelli et al., 2004, through inversion analysis of seismic reflection data suggests that some of upper... Multiple methane sources 3 ] however, using the Eurasia to North America plate motion model not. Started in the form of methane within the formation ( Davis et al.,,... The upper accretionary prism and the underlying backstop are currently undergoing a great deal of compressional pressure 70 years the... Not included major earthquakes in the Nankai Trough is potentially a major source of hydrocarbon fuel, in the imbricate. This article is about earthquakes along the Nankai Trough was in 1944 off the Kii Peninsula 10° it! Zone has been an increase in the last ca, segment E has! Is preserving the porosity ( Spinelli et al., 2006, identified protothrusts and decollement surfaces along Nankai... [ 10 ] recent large-scale earthquake to occur there Nankai megathrust is thought to have at...

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