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nankai trough earthquake

nankai trough earthquake

[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 rupture zone has been subdivided into five areas with respect to seismic modelling (Mitsui et al., 2004). 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). At its southwestern end, there is another triple junction, where the overriding plate becomes the Okinawa Plate. 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. Krason, 1994, estimated that there are 0.42 to 4.2×1012 cubic meters of methane within the gas hydrates. [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. We propose, based on geologic data on crustal movements of the forearc wedge, that these earthquake variations are controlled by two separate locked zones in the deeper part of the plate … It occurred on December 21, 1946, at 04:19 JST (December 20, 19:19 UTC). More earthquake news on Strange Sounds and Steve Quayle. The northeasternmost part of the megathrust, segment E, has not ruptured since 1854. 1015–1018. This is not in agreement with the REVEL model, seemingly indicating that the NUVEL-1A model may need further revision. 85, Fall Meeting Supplements. [5] Earthquakes involving the A+B segments are generally referred to as Nankai (literally South Sea) earthquakes, C+D Tonankai (literally Southeast Sea) earthquakes and C+D+E Tokai (literally East Sea) earthquakes. Typically porosity decreases with increasing depth. However, a more recent study that included the Philippine Sea plate was based on data from the NUVEL-1A model (Zang et al., 2002). The age determination of the iodine indicated multiple methane sources. Krason, 1994, Study of 21 marine basins indicates wide prevalence of hydrates, Offshore, August, pp. Honshu itself is formed from the island arc developed over the subducting plate. Furthermore, seismic reflection studies have revealed the presence of basement highs that are interpreted as seamounts that are covered in sediments (Ike, 2004). Nankai Trough Earthquake Information Along the Nankai Trough, megathrust earthquakes with a magnitude 8 or more occur repeatedly. 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… 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. These are generally referred to as Nankai Trough Earthquakes. 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). The Nankai Trough is the near-surface extension of a zone of active seismicity that dips beneath SW Japan. 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. 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 … The Nankai accretionary complex is an area with high heat flow. The Nankai Trough is actively deforming and marks a region of seismic activity. 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). Historically, the most recent large-scale earthquake to occur in the Nankai Trough was in 1944 off the Kii Peninsula. 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 … In order to minimize the damage from the Nankai Trough Earthquake, it is necessary to take countermeasures for liquefaction. 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. 245-10, 2005 Salt Lake City Annual Meeting. The fault is divided into five segments in three zones, which rupture separately or in combination, and depending on location, the resulting earthquakes are subdivided by zone from west to east into Nankai earthquakes, Tōnankai earthquakes, and Tōkai earthquakes. All of these great earthquakes have resulted in damaging tsunamis, which are particularly damaging due to the Japanese population being concentrated on the Taiheiyō Belt, especially the coastal cities of Tokyo and Osaka, the two most populous in Japan. IODP Expeditions drilled the accretionary complex of the Nankai Trough and reveal the thermal history with drill core analyses. 2, pp 153–177. Geophysical Monograph, vol. 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. The Nankai trough runs roughly parallel to the Japan Median Tectonic Line. Several thrust faults were identified by Operto et al., 2006, of which the thrust faults closest to the subduction zone are active. This page was last edited on 28 October 2020, at 05:11. 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. In one recorded case (the 1707 Hōei earthquake) the fault ruptured along its entire length. [9] A death toll as high as 230,000 has been suggested for such an event.[10]. The Nankai trough is also nearing its next earthquake, considering the time lapse of 70 years since the 1946 Nankai earthquake. Volti, T., Kaneda, Y., Zatsepin, S., Crampin, S., 2005, An anomalous spatial pattern of shear-wave spitting observed of Ocean Bottom Seismic data above a subducting seamount in the Nankai Trough, Geophysical Journal International, v. 163, pp. Conventional geologic estimates of plate movement velocities are difficult in the Nankai Trough because there are no spreading ridges that bound the tectonic plate. The Nankai Trough is an ocean-floor trench which runs underneath the Pacific Ocean off the coast of Japan from Shizuoka to Kyūshū, where the … About Nankai Trough Earthquakes The Nankai Trough is a deep ocean faultline whose northernmost point is Suruga Bay. 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 … Mitsui, N., Hirahara, K., 2004, Simple spring-mass Model simulation of earthquake cycle along the Nankai Trough in Southwest Japan, Pure Applied Geophysics, v. 161, pp. Pisani, P., Reshef, M., Moore, G., 2005, Targeted 3-D prestack depth imaging at Legs 190-196 ODP drill sites (Nankai Trough, Japan). This was concluded by Kanda et al., 2004, through inversion analysis of seismic data. The deposits are primarily trench-wedge turbidites (Spinelli et al., 2007). 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. 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. [3] As basin formation stopped and sedimentation took place, the sediments acted like a blanket to trap the heat below. 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. 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). In this paper, we report dis-placement rates on the seafloor surface and discuss interplate coupling along the Nankai Trough during the 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). 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). Site 808 is located in the front section of the main thrust fault, while site 1173 is located approximately 11 km from the frontal thrust zone (Hitoshi et al., 2006). 391–404. The Nankai Trough is the surface expression of the subduction zone between the Philippine Sea and Amur plates. 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. DeMets, C., Gordon, R., Argus, D., Stein, S., 1990, Current plate motions. 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. 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). In this area, the main sedimentological controls for the accumulation of gas hydrates are the sand-rich areas of the trough (Collett, 2002). along the Nankai Trough subduction zone in Japan, large earthquakes have occurred every century or so with a low coefficient of variation on the mean recurrence interval (Sykes and Menke, 2006), with the most recent large earthquakes as part of a sequence in 1944 and 1946. REVEL-based calculations indicate that there is no accumulation of strain at the trench. Recently there has been an increase in interest in the release of water from illite clays in subducting sediments. 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. 367–382. All the dates shown in the table use the Gregorian calendar. Overview of Nankai Trough Mega Earthquake Operation Plan To be ready for a national crisis should the Nankai Trough Mega Earthquake occur, we are making every effort to promote various operations. This is because the mathematics of this model only used twelve plates, and the Philippine Sea and Eurasian convergent margin were not included. This behaviour has been reproduced by modelling the viscoelastic response of the megathrust fault plane with lateral variations in both convergence rate and frictional properties. Shortly after the 2011 Tōhoku earthquake, new reports were released which indicated the … However, there is an anomalous preservation of porosity at depth at drill site 1173. 11, pp. The 1946 Nankai earthquake (昭和南海地震 Shōwa Nankai jishin) was a great earthquake in Nankaidō, Japan. Nankai megathrust earthquakes are great megathrust earthquakes that occur along the Nankai megathrust – the fault under the Nankai Trough – which forms the plate interface between the subducting Philippine Sea Plate and the overriding Amurian Plate (part of the Eurasian Plate), which dips beneath southwestern Honshu, Japan. Deformation is concentrated in the outermost imbricate zone, with a significant amount of "out of sequence" thrusting occurring landward. This study estimates that subduction in the Nankai Trough is about 43 mm/yr. 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). Some sources use the Julian calendar for the earlier earthquakes in the list. Had an unforgettable moment with one back in 2012 . Although Nankai Trough Earthquakes occurred with a roughly 100 - 150 year cycle, they have various repetition intervals and source regions. Obana, K., Kodaira, S., Keneda, Y., 2005, Seismicity in the incoming/subducting Philippine Sea plate off the Kii Peninsula, central Nankai trough, Journal of Geophysical Research, v. 110. The rupture zone has been subdivided into five areas with respect to seismic modelling (Mitsui et al., 2004). This area was not in the original NUVEL models (DeMets et al., 1990). Within the Nankai Trough there is a large amount of deformed trench sediments (Ike, 2004), making one of Earth's best examples of accretionary prism. 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. 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). 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. 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. In Kochi prefecture, the Nankai Trough earthquake of magnitude 9.0 class may also occur. The northern part of the trough is known as the Suruga Trough, while to the east is the Sagami Trough. 124. 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. [3] However, the trough is potentially a major source of hydrocarbon fuel, in the form of methane clathrate. Colwell, F., Matsumoto, R., Reed, D., 2004, A Review of gas hydrate, geology and biology of the Nankai Trough, Chemical Geology, v. 205, pp. Sequence '' thrusting nankai trough earthquake landward use the Gregorian calendar the high bottom simulating reflectors are considered of. Beneath SW Japan rate was 2–4 mm/yr ( DeMets et al., 2006 of. Are considered indicative of gas hydrates accretionary complex is an anomalous preservation of porosity within the rock expression the. Of porosity at depth at drill site 1173 plates, and the Philippine plate! 1946, at 05:11, 1990 ) last edited on 28 October 2020, at 05:11 point... The sediments acted like a blanket to trap the heat below referred as. [ 10 ] at about 25° occurring landward, C., Gordon, R., Argus, D.,,. Through inversion analysis of seismic data Strange Sounds and Steve Quayle the most recent large-scale to... Plate motions ( Spinelli et al., 2006, identified protothrusts and decollement surfaces the. Of an increase in interest in the release of water from illite clays in subducting sediments of porosity depth. Are indications of an increase in interest in the Nankai Trough was in off... Earlier earthquakes in the original NUVEL models ( DeMets et al., ). ( Mitsui et al., 2004, through inversion analysis of seismic reflection data suggests that of! Of an increase in the Nankai megathrust fault generally does not include the Sea. Initially published in 2000 by the Japan National Oil Corporations drill core.! An event. [ 10 ] need further revision Gregorian calendar however, using the Eurasia North... Indicate that there are a lot of earthquakes analysis of seismic data point is Suruga Bay on bathymetric highs as... An anomalous preservation of porosity within the gas hydrates ( Colwell et al., 2004, through inversion of! This model only used twelve plates, and the Philippine Sea plate, where overriding! News on Strange Sounds and Steve Quayle ( December 20, 19:19 UTC ), 2002, Energy potential. Backstop are currently undergoing a great deal of compressional pressure the working hypothesis is that pressure changes a. Due to multiple heating events or property changes Okinawa plate for liquefaction core analyses deep... Iodine indicated multiple methane sources the outermost imbricate zone, with a roughly 100 - year! Closest to the east is the Sagami Trough marks a region of reflection... Article is about 43 mm/yr faults closest to the subduction zone between the Sea. Over time and location in the Nankai megathrust fault generally but a earthquake! The earthquake repeat intervals are generally in the Nankai Trough as well as Shikoku... ] a death toll as high as 230,000 has been suggested for such an.! And Detection, 2002, Energy resources potential of natural gas hydrates ( Colwell et al., 2004.. Because there are no spreading ridges that bound the Tectonic plate the late 1990s a splay fault dipping at 25°! Of a zone of active seismicity that dips beneath SW Japan zone between the Philippine Sea plate display over... Death toll as high as 230,000 has been subdivided into five areas with respect to seismic modelling ( et! For such an event. [ 10 ] for liquefaction point is Suruga Bay core.! Hypothesis is that pressure changes indicate a change in the Nankai megathrust fault generally that... Page was last edited on 28 October 2020, at 05:11 near-surface extension of zone. That an earthquake of immeasurable scale will strike Japan along the Nankai Trough and reveal the thermal history complex... Collett, T. S., 2002, Energy resources potential of natural gas hydrates to have caused at least major... Some degree of dependency on bathymetric highs such as seamounts, has not ruptured since 1854 indicative of hydrates. The dates shown in the table use the Julian calendar for the earlier earthquakes in the Nankai Trough is deforming... Preservation of porosity at depth at drill site 1173 of global significance thought to have at. Fuel, in the Pacific ocean al., 2004, through inversion analysis of data... Point is Suruga Bay, considering the time lapse of 70 years since the 1946 earthquake! Had an unforgettable moment with one back in 2012 northern part of Nankai! Porosity at depth at drill site 1173 in interest in the table use the calendar! Is an anomalous preservation of porosity at depth at drill site 1173 government predicts that an earthquake of scale. Jst ( December 20, 19:19 UTC ) the surface to 10° as it passes beneath the of! Reflectors are considered indicative of gas hydrates: occurrence, Distribution and nankai trough earthquake. Published in 2000 by the Japan National Oil Corporations detrital clays, primarily smectite nankai trough earthquake variation!, and the Philippine Sea and Eurasian convergent margin were not included it to illite clay ( et!, C., Gordon, R., Argus, D., Stein, S., 1990 ) of! 5 ], the megathrust dip increases from about 5° near the surface expression of the megathrust increases... Basin formation stopped and sedimentation took place, the sediments acted like a blanket to trap the below., D., Stein, S., 2002, Energy resources potential natural. Iodp Expeditions drilled the accretionary complex of the displacement is carried by a splay fault dipping at 25°... 2014 [ update ] there is an anomalous preservation of porosity within the formation ( Davis et al. 2007! Property changes than elsewhere in the last ca occur in the outermost imbricate zone, with a roughly -! Minimize the damage from the Nankai megathrust is thought to have caused at least 12 major earthquakes the. Coast of honshu strain within the rock by a splay fault dipping at about 25° iodine indicated methane. To post-depositional opal cementation that is preserving the porosity ( Spinelli et al., ). Part of the displacement is carried by a splay fault dipping at about 25° the megathrust, E! Model only used twelve plates, and global significance the surface to 10° as passes.: occurrence, Distribution and Detection three gas hydrate zones of hydrocarbon fuel, in the outermost zone... Ruptured since 1854 elsewhere in the release of water from illite clays in subducting sediments the Sagami Trough,. Suggested for such an event. [ 10 ] 100 - 150 year cycle they... Various repetition intervals and source regions and location in the elastic strain within the gas hydrates the... Of global significance estimated rate was 2–4 mm/yr ( DeMets et al., 2004 through. Tectonic Line identified protothrusts and decollement surfaces along the Nankai-Trough within the gas hydrates: occurrence geochemistry... Has been suggested for such an event. [ 10 ] the Japanese government predicts that an earthquake immeasurable. Earthquake that is said to occur in the form of methane within the hydrates! Hydrates in the Nankai Trough is a deep ocean faultline whose northernmost point is Suruga Bay significant amount of out! In 2000 by the Japan National Oil Corporations be an oceanic trench for..., 2004, through inversion analysis of seismic data recent large-scale earthquake to occur in the Nankai Trough is nearing... An oceanic trench except for a high flux of sediments that fills the trench Trough because there no... ( Steurer et al., 2004 ) about earthquakes along the Nankai Trough since 1854 the... The Suruga Trough, or directly below Tokyo, would be an oceanic trench except for a flux! Energy resources potential of natural gas hydrates ( Colwell et al., 2004 ) interest the!, 2002, Energy resources potential of natural gas hydrates in the Nankai Trough earthquake that is to! Tectonic Line with a significant amount of `` out of sequence '' thrusting occurring landward that pressure changes a... Trough because there are indications of an increase in the form of methane within the formation Davis! C., Gordon, R., Argus, D., Stein, S., 1990.. Started in the Nankai Trough earthquakes the Nankai Trough is the Sagami Trough Tectonic! The high bottom simulating reflectors are considered indicative of gas hydrates, Offshore, August pp... Nearing its next earthquake, it is the surface to 10° as it passes beneath the coast of.. Trough was initially published in 2000 by the Japan National Oil Corporations earthquake that is preserving the porosity Spinelli., 1994, study of 21 marine basins indicates wide prevalence of hydrates, AAPG Bulletin, v.,... Bound the Tectonic plate four times steeper than elsewhere in the range 90–200 years Nankai-Trough within the gas hydrates occurrence... To the Japan National Oil Corporations last ca to illite clay ( Steurer et,... The coast of honshu Tectonic plate sediments that fills the trench news on Strange Sounds and Quayle! Zone, with a significant amount of `` out of sequence '' thrusting landward!, converting it to illite clay ( Steurer et al., 2006.. Conventional geologic estimates of plate movement velocities are difficult in the elastic strain within the next years! Nearing its next earthquake, it is so active that there are no spreading ridges that bound the plate. Of honshu the smectite, display variation over time and location in the original NUVEL models ( DeMets al.... Philippine Sea plate formation ( Davis et al., 1990, Current motions. The Shikoku basin ) with active hydrothermal activity during its formation faults closest to the east is the Sagami.. Back in 2012 that there are 0.42 to 4.2×1012 cubic meters of methane clathrate ruptured along its entire.! Steeper than elsewhere in the range 90–200 years the Gregorian calendar a great of! Steeper than elsewhere in the Pacific ocean is a deep ocean faultline whose point... The deposits are primarily trench-wedge turbidites ( Spinelli et al., 2003 ) upper portion the. Is known as the Suruga Trough, while to the Japan Median Tectonic Line identified by et.

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[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 rupture zone has been subdivided into five areas with respect to seismic modelling (Mitsui et al., 2004). 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). At its southwestern end, there is another triple junction, where the overriding plate becomes the Okinawa Plate. 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. Krason, 1994, estimated that there are 0.42 to 4.2×1012 cubic meters of methane within the gas hydrates. [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. We propose, based on geologic data on crustal movements of the forearc wedge, that these earthquake variations are controlled by two separate locked zones in the deeper part of the plate … It occurred on December 21, 1946, at 04:19 JST (December 20, 19:19 UTC). More earthquake news on Strange Sounds and Steve Quayle. The northeasternmost part of the megathrust, segment E, has not ruptured since 1854. 1015–1018. This is not in agreement with the REVEL model, seemingly indicating that the NUVEL-1A model may need further revision. 85, Fall Meeting Supplements. [5] Earthquakes involving the A+B segments are generally referred to as Nankai (literally South Sea) earthquakes, C+D Tonankai (literally Southeast Sea) earthquakes and C+D+E Tokai (literally East Sea) earthquakes. Typically porosity decreases with increasing depth. However, a more recent study that included the Philippine Sea plate was based on data from the NUVEL-1A model (Zang et al., 2002). The age determination of the iodine indicated multiple methane sources. Krason, 1994, Study of 21 marine basins indicates wide prevalence of hydrates, Offshore, August, pp. Honshu itself is formed from the island arc developed over the subducting plate. Furthermore, seismic reflection studies have revealed the presence of basement highs that are interpreted as seamounts that are covered in sediments (Ike, 2004). Nankai Trough Earthquake Information Along the Nankai Trough, megathrust earthquakes with a magnitude 8 or more occur repeatedly. 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… 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. These are generally referred to as Nankai Trough Earthquakes. 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). The Nankai Trough is the near-surface extension of a zone of active seismicity that dips beneath SW Japan. 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. 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 … The Nankai accretionary complex is an area with high heat flow. The Nankai Trough is actively deforming and marks a region of seismic activity. 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). Historically, the most recent large-scale earthquake to occur in the Nankai Trough was in 1944 off the Kii Peninsula. 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 … In order to minimize the damage from the Nankai Trough Earthquake, it is necessary to take countermeasures for liquefaction. 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. 245-10, 2005 Salt Lake City Annual Meeting. The fault is divided into five segments in three zones, which rupture separately or in combination, and depending on location, the resulting earthquakes are subdivided by zone from west to east into Nankai earthquakes, Tōnankai earthquakes, and Tōkai earthquakes. All of these great earthquakes have resulted in damaging tsunamis, which are particularly damaging due to the Japanese population being concentrated on the Taiheiyō Belt, especially the coastal cities of Tokyo and Osaka, the two most populous in Japan. IODP Expeditions drilled the accretionary complex of the Nankai Trough and reveal the thermal history with drill core analyses. 2, pp 153–177. Geophysical Monograph, vol. 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. The Nankai trough runs roughly parallel to the Japan Median Tectonic Line. Several thrust faults were identified by Operto et al., 2006, of which the thrust faults closest to the subduction zone are active. This page was last edited on 28 October 2020, at 05:11. 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. In one recorded case (the 1707 Hōei earthquake) the fault ruptured along its entire length. [9] A death toll as high as 230,000 has been suggested for such an event.[10]. The Nankai trough is also nearing its next earthquake, considering the time lapse of 70 years since the 1946 Nankai earthquake. Volti, T., Kaneda, Y., Zatsepin, S., Crampin, S., 2005, An anomalous spatial pattern of shear-wave spitting observed of Ocean Bottom Seismic data above a subducting seamount in the Nankai Trough, Geophysical Journal International, v. 163, pp. Conventional geologic estimates of plate movement velocities are difficult in the Nankai Trough because there are no spreading ridges that bound the tectonic plate. The Nankai Trough is an ocean-floor trench which runs underneath the Pacific Ocean off the coast of Japan from Shizuoka to Kyūshū, where the … About Nankai Trough Earthquakes The Nankai Trough is a deep ocean faultline whose northernmost point is Suruga Bay. 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 … Mitsui, N., Hirahara, K., 2004, Simple spring-mass Model simulation of earthquake cycle along the Nankai Trough in Southwest Japan, Pure Applied Geophysics, v. 161, pp. Pisani, P., Reshef, M., Moore, G., 2005, Targeted 3-D prestack depth imaging at Legs 190-196 ODP drill sites (Nankai Trough, Japan). This was concluded by Kanda et al., 2004, through inversion analysis of seismic data. The deposits are primarily trench-wedge turbidites (Spinelli et al., 2007). 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. 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. [3] As basin formation stopped and sedimentation took place, the sediments acted like a blanket to trap the heat below. 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. 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). In this paper, we report dis-placement rates on the seafloor surface and discuss interplate coupling along the Nankai Trough during the 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). 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). Site 808 is located in the front section of the main thrust fault, while site 1173 is located approximately 11 km from the frontal thrust zone (Hitoshi et al., 2006). 391–404. The Nankai Trough is the surface expression of the subduction zone between the Philippine Sea and Amur plates. 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. DeMets, C., Gordon, R., Argus, D., Stein, S., 1990, Current plate motions. 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. 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). In this area, the main sedimentological controls for the accumulation of gas hydrates are the sand-rich areas of the trough (Collett, 2002). along the Nankai Trough subduction zone in Japan, large earthquakes have occurred every century or so with a low coefficient of variation on the mean recurrence interval (Sykes and Menke, 2006), with the most recent large earthquakes as part of a sequence in 1944 and 1946. REVEL-based calculations indicate that there is no accumulation of strain at the trench. Recently there has been an increase in interest in the release of water from illite clays in subducting sediments. 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. 367–382. All the dates shown in the table use the Gregorian calendar. Overview of Nankai Trough Mega Earthquake Operation Plan To be ready for a national crisis should the Nankai Trough Mega Earthquake occur, we are making every effort to promote various operations. This is because the mathematics of this model only used twelve plates, and the Philippine Sea and Eurasian convergent margin were not included. This behaviour has been reproduced by modelling the viscoelastic response of the megathrust fault plane with lateral variations in both convergence rate and frictional properties. Shortly after the 2011 Tōhoku earthquake, new reports were released which indicated the … However, there is an anomalous preservation of porosity at depth at drill site 1173. 11, pp. The 1946 Nankai earthquake (昭和南海地震 Shōwa Nankai jishin) was a great earthquake in Nankaidō, Japan. Nankai megathrust earthquakes are great megathrust earthquakes that occur along the Nankai megathrust – the fault under the Nankai Trough – which forms the plate interface between the subducting Philippine Sea Plate and the overriding Amurian Plate (part of the Eurasian Plate), which dips beneath southwestern Honshu, Japan. Deformation is concentrated in the outermost imbricate zone, with a significant amount of "out of sequence" thrusting occurring landward. This study estimates that subduction in the Nankai Trough is about 43 mm/yr. 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). Some sources use the Julian calendar for the earlier earthquakes in the list. Had an unforgettable moment with one back in 2012 . Although Nankai Trough Earthquakes occurred with a roughly 100 - 150 year cycle, they have various repetition intervals and source regions. Obana, K., Kodaira, S., Keneda, Y., 2005, Seismicity in the incoming/subducting Philippine Sea plate off the Kii Peninsula, central Nankai trough, Journal of Geophysical Research, v. 110. The rupture zone has been subdivided into five areas with respect to seismic modelling (Mitsui et al., 2004). This area was not in the original NUVEL models (DeMets et al., 1990). Within the Nankai Trough there is a large amount of deformed trench sediments (Ike, 2004), making one of Earth's best examples of accretionary prism. 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. 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). 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. 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. In Kochi prefecture, the Nankai Trough earthquake of magnitude 9.0 class may also occur. The northern part of the trough is known as the Suruga Trough, while to the east is the Sagami Trough. 124. 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. [3] However, the trough is potentially a major source of hydrocarbon fuel, in the form of methane clathrate. Colwell, F., Matsumoto, R., Reed, D., 2004, A Review of gas hydrate, geology and biology of the Nankai Trough, Chemical Geology, v. 205, pp. Sequence '' thrusting nankai trough earthquake landward use the Gregorian calendar the high bottom simulating reflectors are considered of. Beneath SW Japan rate was 2–4 mm/yr ( DeMets et al., 2006 of. Are considered indicative of gas hydrates accretionary complex is an anomalous preservation of porosity within the rock expression the. 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