Global compilation of the LVL-410 observations. RF: receiver functions, LVL: low velocity layer.
| S.N. . | Region . | Method . | Finding . | Cause . | Reference . |
|---|---|---|---|---|---|
| 1 | East of southern Africa | S RFs | Observed intermittently between 280 and 360 km depth | Dehydration melting due to thermal plume, causal relation with large volume of flood basalts | Vinnik & Farra (2002) |
| 2 | Arabian plate | P & S RFs | 350–410 km deep, absent beneath Gulf of Aden | Marks separation of dry mantle root of Arabian Plate from the wet underlying mantle | Vinnik et al. (2003) |
| 3 | NW US | S wave triplications | 20–90 km thick intermittent LVLs with 5 per cent drop in shear wave velocity | LVLs possibly linked to Farallon Plate subduction and backarc extension | Song et al. (2004) |
| 4 | Yellowstone Hotspot US | P RFs | At 380 km depth | Release of water from mantle flux across 410 km | Fee & Dueker (2004) |
| 5 | Eastern Mexico | P & S wave triplications | 50 km thick LVL above 410 km discontinuity | Partial melting induced by water release from the transition zone | Gao et al. (2006) |
| 6 | Japan (Northern Honshu Slab) | P wave triplications | Excess temperature of 200 K and <1 per cent melt can explain the LVL | Thermal origin, partial melting | Obayashi et al. (2006) |
| 7 | Northern Rocky Mountains | P RFs | |$\sim$|22 km thick layer with 8.9 per cent shear wave velocity reduction | Dehydration melting due to difference in water content in the MTZ and overlying mantle. Affirms water filter model | Jasbinsek & Dueker (2007) |
| 8 | Tasman and Coral Seas | ScS reverberations | At |$\sim$|352 km depth, atop the 410 km discontinuity | Partial melting resulting from volatile induced melting | Courtier & Revenaugh (2007) |
| 9 | SW US (Tucson) | Electro-Magnetics | Intermittent, not a global feature, 5–30 km thick layer atop 410 km discontinuity | Dehydration melting. Supports water filter model | Toffelmier & Tyburczy (2007) |
| 10 | Global | S RFs | |$\sim$|350 km depth | Association with Mesozoic/Cenozoic mantle plumes, dehydration of water bearing silicates. Contradicts water filter model | Vinnik & Farra (2007) |
| 11 | Kalahari Craton (Africa) | P & S RFs | 300–350 km depth | Remains of a giant basaltic reservoir that formerly fed the flood basalts or the ceiling of a layer of dense molten silicates generated by transformations above 410 km | Wittlinger & Farra (2007) |
| 12 | Japan (Oceanward Honshu Slab) | ScS rever-berations | 50–75 km thick layer at an average depth of 356 km | Partial melt entrained from above by subduction or produced in situ by combined effects of water and temperature | Bagley et al. (2009) |
| 13 | California US | S RFs | |$\sim$|2 per cent reduction in S velocity | Dehydration melting due to difference in water solubility across 410 km, observed in the vicinity of hot spot | Vinnik et al. (2010) |
| 14 | Global | P RFs | Observed globally, no particular affinity to a particular tectonic environment | Weaker water storage capacity of mantle minerals may induce partial melting of water-bearing silicates throughout | Tauzin et al. (2010) |
| 15 | NW Canada | P & S RFs | |$\sim$|36 km thick layer with an S velocity contrast of −7.8 per cent at a nominal depth of |$\sim$|340 km | Possibly dense, hydrous, silicate melt ponding over the 410 km discontinuity | Schaeffer & Bostock (2010) |
| 16 | SW part of North America | P RFs | 4.6 per cent shear velocity reduction | Melt layer. Supports transition zone water filter model | Jasbinsek et al. (2010) |
| 17 | Western US | P RFs | 25–60 km thick layer above 410 km discontinuity | Partial melt resulting from upwelling of hydrated mantle due to water solubility contrast across 410 km | Schmandt et al. (2011) |
| 18 | Western US | P RFs | 19.1 to 98.8 km thick layer at 350 km depth | Increased water content due to oceanic material accumulated in the last 100 Myr. | Tauzin et al. (2013) |
| 19 | Hawaii | P RFs | Layer at |$\sim$|355 km depth | Combined effects of water and temperature | Huckfeldt et al. (2013) |
| 20 | Central Mexico | P RFs | LVL atop 410 km discontinuity. Seen on the continental side where the slab pierces 410 km | Hydration due to interaction of the subducted slab with the 410 km | Pérez-Campos & Clayton (2014) |
| 21 | Gibraltar Arc | P & S RFs | An intermittent, |$\sim$|50 km LVL atop 410 km near the Atlantic margin | Water release and melting atop 410 km discontinuity | Morais et al. (2015) |
| 22 | Afar Triple Junction | P RFs | Stable melt layer atop 410 km | Hydrous upwelling creating melt layer atop 410 km | Thompson et al. (2015) |
| 23 | Ibero-Maghrebian region | P RFs | Presence of low velocity layer atop 410 km | Increase in water concentration in the TZ due to dehydration of a stagnant slab | Bonatto et al. (2015) |
| 24 | Japan Subduction Zone | P RFs | Intermittent LVZ atop the 410 km discontinuity | Dehydration melting, interactions between subducted slab and surrounding mantle | Liu et al. (2016) |
| 25 | Western US | P RFs | 25–70 km thick LVL with a 1.6 per cent reduction in shear wave speed | Compositional heterogeneity, caused by release of volatiles from the subducted Farallon slab | Hier-Majumder & Tauzin (2017) |
| 26 | NW Pacific and the margin of Eastern Asia | P RFs | 50 km thick layer atop 410 km with a −2 to −4 per cent low shear wave velocity, global feature | Compositional heterogeneities | Tauzin et al. (2017) |
| 27 | SE Tibetan Plateau | P wave triplications | 20–40 km thick LVL with a P-wave velocity reduction of 5.3 to 4.3 per cent | Partial melting induced by water and/or other volatiles released from subduction of the Indian Plate and the stagnant Pacific Plate | Li et al. (2017) |
| 28 | Pacific Ocean | SS precursors | Lateral variation, global presence | Partial melting due to dehydration of ascending mantle | Wei & Shearer (2017) |
| 29 | SE Asia | P RFs | |$\sim$|30–50 km thick LVL atop 410 km at |$\sim$|368 km depth | Water induced melt layer related to earlier subductions | Wölbern & Rümpker (2018) |
| 30 | European Alps | P RFs | Observed near Alpine Orogeny | Upwelling of water rich rocks from MTZ in response to downwelled materials from the orogeny | Liu et al. (2018) |
| 31 | Northern Anatolia | P RFs | Evidence for Low-velocity zones above the 410 km discontinuity | Hydration of the MTZ from the Tethys/Cyprus slab and upward convection of MTZ material into the upper mantle | Taylor et al. (2018) |
| 32 | NE part of South China Sea | P wave triplications | 92.5 |$\pm$| 11 km thick LVL with a P-velocity decrease of 1.5 |$\pm$| 0.1 per cent | Dehydration melting of a Mesozoic Oceanic plate | Guohui et al. (2019) |
| 33 | Eastern South China | P wave triplications | 20–57 km thick LVL with a lateral variation | Related to Pacific Plate subduction, based on melt fractions estimates | Ma et al. (2020) |
| 34 | Colorado Plateau US | P RFs | Low velocity regions having −1.8 per cent low average amplitude compared to Z component | Dehydration melting, supports water filter model at a small scale | Zhang & Dueker (2020) |
| 35 | Northern South China Sea | P wave triplications | 2.0–2.5 per cent decrease in P-wave velocity | Partial melting induced by upwelling MTZ materials, hydrated by water released from stagnant slab | Li et al. (2020) |
| 36 | NW Pacific Subduction Zone | P & S wave triplications | |$\sim$|55–80 km thick low velocity layer | Melts caused by hydrous stagnant slab | Han et al. (2021) |
| 37 | Yellowstone US | P RFs | 10–50 km LVL above 410 km discontinuity | Water release, phase transformations induced by the descent of a Farallon slab fragment and ascent of deeply rooted Yellowstone plume | Frazer & Park (2021) |
| 38 | Western Junggar | P and SH triplications | 29 km thick LVL with a reduction of 5.6 per cent in SH and 4.4 per cent in P velocity. | Upwelling through a slab window due to mid-oceanic ridge subduction or self-buoyancy | Li et al. (2022c) |
| 39 | Qiangtang Terrane | P wave triplications | 36 km thick LVL with a P velocity drop of 2 per cent | Hydrous partial melt affected by dehydration and temperature | Li et al. (2022a) |
| 40 | Western Central Asian Orogenic Belt | P and sP triplications | 21–23 km thick LVL, with a P-wave velocity drop of 5.7–5.8 per cent | Partial melting induced by water and/or other volatiles released from the subducted Paleo Asian oceanic slab | Li et al. (2022b) |
| 41 | North-Central Pacific Ocean | SS precursors | Dehydration induced partial melting | Sharp interface (|$\le$|10 km at 0.5 Hz) | Frazer & Park (2023) |
| S.N. . | Region . | Method . | Finding . | Cause . | Reference . |
|---|---|---|---|---|---|
| 1 | East of southern Africa | S RFs | Observed intermittently between 280 and 360 km depth | Dehydration melting due to thermal plume, causal relation with large volume of flood basalts | Vinnik & Farra (2002) |
| 2 | Arabian plate | P & S RFs | 350–410 km deep, absent beneath Gulf of Aden | Marks separation of dry mantle root of Arabian Plate from the wet underlying mantle | Vinnik et al. (2003) |
| 3 | NW US | S wave triplications | 20–90 km thick intermittent LVLs with 5 per cent drop in shear wave velocity | LVLs possibly linked to Farallon Plate subduction and backarc extension | Song et al. (2004) |
| 4 | Yellowstone Hotspot US | P RFs | At 380 km depth | Release of water from mantle flux across 410 km | Fee & Dueker (2004) |
| 5 | Eastern Mexico | P & S wave triplications | 50 km thick LVL above 410 km discontinuity | Partial melting induced by water release from the transition zone | Gao et al. (2006) |
| 6 | Japan (Northern Honshu Slab) | P wave triplications | Excess temperature of 200 K and <1 per cent melt can explain the LVL | Thermal origin, partial melting | Obayashi et al. (2006) |
| 7 | Northern Rocky Mountains | P RFs | |$\sim$|22 km thick layer with 8.9 per cent shear wave velocity reduction | Dehydration melting due to difference in water content in the MTZ and overlying mantle. Affirms water filter model | Jasbinsek & Dueker (2007) |
| 8 | Tasman and Coral Seas | ScS reverberations | At |$\sim$|352 km depth, atop the 410 km discontinuity | Partial melting resulting from volatile induced melting | Courtier & Revenaugh (2007) |
| 9 | SW US (Tucson) | Electro-Magnetics | Intermittent, not a global feature, 5–30 km thick layer atop 410 km discontinuity | Dehydration melting. Supports water filter model | Toffelmier & Tyburczy (2007) |
| 10 | Global | S RFs | |$\sim$|350 km depth | Association with Mesozoic/Cenozoic mantle plumes, dehydration of water bearing silicates. Contradicts water filter model | Vinnik & Farra (2007) |
| 11 | Kalahari Craton (Africa) | P & S RFs | 300–350 km depth | Remains of a giant basaltic reservoir that formerly fed the flood basalts or the ceiling of a layer of dense molten silicates generated by transformations above 410 km | Wittlinger & Farra (2007) |
| 12 | Japan (Oceanward Honshu Slab) | ScS rever-berations | 50–75 km thick layer at an average depth of 356 km | Partial melt entrained from above by subduction or produced in situ by combined effects of water and temperature | Bagley et al. (2009) |
| 13 | California US | S RFs | |$\sim$|2 per cent reduction in S velocity | Dehydration melting due to difference in water solubility across 410 km, observed in the vicinity of hot spot | Vinnik et al. (2010) |
| 14 | Global | P RFs | Observed globally, no particular affinity to a particular tectonic environment | Weaker water storage capacity of mantle minerals may induce partial melting of water-bearing silicates throughout | Tauzin et al. (2010) |
| 15 | NW Canada | P & S RFs | |$\sim$|36 km thick layer with an S velocity contrast of −7.8 per cent at a nominal depth of |$\sim$|340 km | Possibly dense, hydrous, silicate melt ponding over the 410 km discontinuity | Schaeffer & Bostock (2010) |
| 16 | SW part of North America | P RFs | 4.6 per cent shear velocity reduction | Melt layer. Supports transition zone water filter model | Jasbinsek et al. (2010) |
| 17 | Western US | P RFs | 25–60 km thick layer above 410 km discontinuity | Partial melt resulting from upwelling of hydrated mantle due to water solubility contrast across 410 km | Schmandt et al. (2011) |
| 18 | Western US | P RFs | 19.1 to 98.8 km thick layer at 350 km depth | Increased water content due to oceanic material accumulated in the last 100 Myr. | Tauzin et al. (2013) |
| 19 | Hawaii | P RFs | Layer at |$\sim$|355 km depth | Combined effects of water and temperature | Huckfeldt et al. (2013) |
| 20 | Central Mexico | P RFs | LVL atop 410 km discontinuity. Seen on the continental side where the slab pierces 410 km | Hydration due to interaction of the subducted slab with the 410 km | Pérez-Campos & Clayton (2014) |
| 21 | Gibraltar Arc | P & S RFs | An intermittent, |$\sim$|50 km LVL atop 410 km near the Atlantic margin | Water release and melting atop 410 km discontinuity | Morais et al. (2015) |
| 22 | Afar Triple Junction | P RFs | Stable melt layer atop 410 km | Hydrous upwelling creating melt layer atop 410 km | Thompson et al. (2015) |
| 23 | Ibero-Maghrebian region | P RFs | Presence of low velocity layer atop 410 km | Increase in water concentration in the TZ due to dehydration of a stagnant slab | Bonatto et al. (2015) |
| 24 | Japan Subduction Zone | P RFs | Intermittent LVZ atop the 410 km discontinuity | Dehydration melting, interactions between subducted slab and surrounding mantle | Liu et al. (2016) |
| 25 | Western US | P RFs | 25–70 km thick LVL with a 1.6 per cent reduction in shear wave speed | Compositional heterogeneity, caused by release of volatiles from the subducted Farallon slab | Hier-Majumder & Tauzin (2017) |
| 26 | NW Pacific and the margin of Eastern Asia | P RFs | 50 km thick layer atop 410 km with a −2 to −4 per cent low shear wave velocity, global feature | Compositional heterogeneities | Tauzin et al. (2017) |
| 27 | SE Tibetan Plateau | P wave triplications | 20–40 km thick LVL with a P-wave velocity reduction of 5.3 to 4.3 per cent | Partial melting induced by water and/or other volatiles released from subduction of the Indian Plate and the stagnant Pacific Plate | Li et al. (2017) |
| 28 | Pacific Ocean | SS precursors | Lateral variation, global presence | Partial melting due to dehydration of ascending mantle | Wei & Shearer (2017) |
| 29 | SE Asia | P RFs | |$\sim$|30–50 km thick LVL atop 410 km at |$\sim$|368 km depth | Water induced melt layer related to earlier subductions | Wölbern & Rümpker (2018) |
| 30 | European Alps | P RFs | Observed near Alpine Orogeny | Upwelling of water rich rocks from MTZ in response to downwelled materials from the orogeny | Liu et al. (2018) |
| 31 | Northern Anatolia | P RFs | Evidence for Low-velocity zones above the 410 km discontinuity | Hydration of the MTZ from the Tethys/Cyprus slab and upward convection of MTZ material into the upper mantle | Taylor et al. (2018) |
| 32 | NE part of South China Sea | P wave triplications | 92.5 |$\pm$| 11 km thick LVL with a P-velocity decrease of 1.5 |$\pm$| 0.1 per cent | Dehydration melting of a Mesozoic Oceanic plate | Guohui et al. (2019) |
| 33 | Eastern South China | P wave triplications | 20–57 km thick LVL with a lateral variation | Related to Pacific Plate subduction, based on melt fractions estimates | Ma et al. (2020) |
| 34 | Colorado Plateau US | P RFs | Low velocity regions having −1.8 per cent low average amplitude compared to Z component | Dehydration melting, supports water filter model at a small scale | Zhang & Dueker (2020) |
| 35 | Northern South China Sea | P wave triplications | 2.0–2.5 per cent decrease in P-wave velocity | Partial melting induced by upwelling MTZ materials, hydrated by water released from stagnant slab | Li et al. (2020) |
| 36 | NW Pacific Subduction Zone | P & S wave triplications | |$\sim$|55–80 km thick low velocity layer | Melts caused by hydrous stagnant slab | Han et al. (2021) |
| 37 | Yellowstone US | P RFs | 10–50 km LVL above 410 km discontinuity | Water release, phase transformations induced by the descent of a Farallon slab fragment and ascent of deeply rooted Yellowstone plume | Frazer & Park (2021) |
| 38 | Western Junggar | P and SH triplications | 29 km thick LVL with a reduction of 5.6 per cent in SH and 4.4 per cent in P velocity. | Upwelling through a slab window due to mid-oceanic ridge subduction or self-buoyancy | Li et al. (2022c) |
| 39 | Qiangtang Terrane | P wave triplications | 36 km thick LVL with a P velocity drop of 2 per cent | Hydrous partial melt affected by dehydration and temperature | Li et al. (2022a) |
| 40 | Western Central Asian Orogenic Belt | P and sP triplications | 21–23 km thick LVL, with a P-wave velocity drop of 5.7–5.8 per cent | Partial melting induced by water and/or other volatiles released from the subducted Paleo Asian oceanic slab | Li et al. (2022b) |
| 41 | North-Central Pacific Ocean | SS precursors | Dehydration induced partial melting | Sharp interface (|$\le$|10 km at 0.5 Hz) | Frazer & Park (2023) |
Global compilation of the LVL-410 observations. RF: receiver functions, LVL: low velocity layer.
| S.N. . | Region . | Method . | Finding . | Cause . | Reference . |
|---|---|---|---|---|---|
| 1 | East of southern Africa | S RFs | Observed intermittently between 280 and 360 km depth | Dehydration melting due to thermal plume, causal relation with large volume of flood basalts | Vinnik & Farra (2002) |
| 2 | Arabian plate | P & S RFs | 350–410 km deep, absent beneath Gulf of Aden | Marks separation of dry mantle root of Arabian Plate from the wet underlying mantle | Vinnik et al. (2003) |
| 3 | NW US | S wave triplications | 20–90 km thick intermittent LVLs with 5 per cent drop in shear wave velocity | LVLs possibly linked to Farallon Plate subduction and backarc extension | Song et al. (2004) |
| 4 | Yellowstone Hotspot US | P RFs | At 380 km depth | Release of water from mantle flux across 410 km | Fee & Dueker (2004) |
| 5 | Eastern Mexico | P & S wave triplications | 50 km thick LVL above 410 km discontinuity | Partial melting induced by water release from the transition zone | Gao et al. (2006) |
| 6 | Japan (Northern Honshu Slab) | P wave triplications | Excess temperature of 200 K and <1 per cent melt can explain the LVL | Thermal origin, partial melting | Obayashi et al. (2006) |
| 7 | Northern Rocky Mountains | P RFs | |$\sim$|22 km thick layer with 8.9 per cent shear wave velocity reduction | Dehydration melting due to difference in water content in the MTZ and overlying mantle. Affirms water filter model | Jasbinsek & Dueker (2007) |
| 8 | Tasman and Coral Seas | ScS reverberations | At |$\sim$|352 km depth, atop the 410 km discontinuity | Partial melting resulting from volatile induced melting | Courtier & Revenaugh (2007) |
| 9 | SW US (Tucson) | Electro-Magnetics | Intermittent, not a global feature, 5–30 km thick layer atop 410 km discontinuity | Dehydration melting. Supports water filter model | Toffelmier & Tyburczy (2007) |
| 10 | Global | S RFs | |$\sim$|350 km depth | Association with Mesozoic/Cenozoic mantle plumes, dehydration of water bearing silicates. Contradicts water filter model | Vinnik & Farra (2007) |
| 11 | Kalahari Craton (Africa) | P & S RFs | 300–350 km depth | Remains of a giant basaltic reservoir that formerly fed the flood basalts or the ceiling of a layer of dense molten silicates generated by transformations above 410 km | Wittlinger & Farra (2007) |
| 12 | Japan (Oceanward Honshu Slab) | ScS rever-berations | 50–75 km thick layer at an average depth of 356 km | Partial melt entrained from above by subduction or produced in situ by combined effects of water and temperature | Bagley et al. (2009) |
| 13 | California US | S RFs | |$\sim$|2 per cent reduction in S velocity | Dehydration melting due to difference in water solubility across 410 km, observed in the vicinity of hot spot | Vinnik et al. (2010) |
| 14 | Global | P RFs | Observed globally, no particular affinity to a particular tectonic environment | Weaker water storage capacity of mantle minerals may induce partial melting of water-bearing silicates throughout | Tauzin et al. (2010) |
| 15 | NW Canada | P & S RFs | |$\sim$|36 km thick layer with an S velocity contrast of −7.8 per cent at a nominal depth of |$\sim$|340 km | Possibly dense, hydrous, silicate melt ponding over the 410 km discontinuity | Schaeffer & Bostock (2010) |
| 16 | SW part of North America | P RFs | 4.6 per cent shear velocity reduction | Melt layer. Supports transition zone water filter model | Jasbinsek et al. (2010) |
| 17 | Western US | P RFs | 25–60 km thick layer above 410 km discontinuity | Partial melt resulting from upwelling of hydrated mantle due to water solubility contrast across 410 km | Schmandt et al. (2011) |
| 18 | Western US | P RFs | 19.1 to 98.8 km thick layer at 350 km depth | Increased water content due to oceanic material accumulated in the last 100 Myr. | Tauzin et al. (2013) |
| 19 | Hawaii | P RFs | Layer at |$\sim$|355 km depth | Combined effects of water and temperature | Huckfeldt et al. (2013) |
| 20 | Central Mexico | P RFs | LVL atop 410 km discontinuity. Seen on the continental side where the slab pierces 410 km | Hydration due to interaction of the subducted slab with the 410 km | Pérez-Campos & Clayton (2014) |
| 21 | Gibraltar Arc | P & S RFs | An intermittent, |$\sim$|50 km LVL atop 410 km near the Atlantic margin | Water release and melting atop 410 km discontinuity | Morais et al. (2015) |
| 22 | Afar Triple Junction | P RFs | Stable melt layer atop 410 km | Hydrous upwelling creating melt layer atop 410 km | Thompson et al. (2015) |
| 23 | Ibero-Maghrebian region | P RFs | Presence of low velocity layer atop 410 km | Increase in water concentration in the TZ due to dehydration of a stagnant slab | Bonatto et al. (2015) |
| 24 | Japan Subduction Zone | P RFs | Intermittent LVZ atop the 410 km discontinuity | Dehydration melting, interactions between subducted slab and surrounding mantle | Liu et al. (2016) |
| 25 | Western US | P RFs | 25–70 km thick LVL with a 1.6 per cent reduction in shear wave speed | Compositional heterogeneity, caused by release of volatiles from the subducted Farallon slab | Hier-Majumder & Tauzin (2017) |
| 26 | NW Pacific and the margin of Eastern Asia | P RFs | 50 km thick layer atop 410 km with a −2 to −4 per cent low shear wave velocity, global feature | Compositional heterogeneities | Tauzin et al. (2017) |
| 27 | SE Tibetan Plateau | P wave triplications | 20–40 km thick LVL with a P-wave velocity reduction of 5.3 to 4.3 per cent | Partial melting induced by water and/or other volatiles released from subduction of the Indian Plate and the stagnant Pacific Plate | Li et al. (2017) |
| 28 | Pacific Ocean | SS precursors | Lateral variation, global presence | Partial melting due to dehydration of ascending mantle | Wei & Shearer (2017) |
| 29 | SE Asia | P RFs | |$\sim$|30–50 km thick LVL atop 410 km at |$\sim$|368 km depth | Water induced melt layer related to earlier subductions | Wölbern & Rümpker (2018) |
| 30 | European Alps | P RFs | Observed near Alpine Orogeny | Upwelling of water rich rocks from MTZ in response to downwelled materials from the orogeny | Liu et al. (2018) |
| 31 | Northern Anatolia | P RFs | Evidence for Low-velocity zones above the 410 km discontinuity | Hydration of the MTZ from the Tethys/Cyprus slab and upward convection of MTZ material into the upper mantle | Taylor et al. (2018) |
| 32 | NE part of South China Sea | P wave triplications | 92.5 |$\pm$| 11 km thick LVL with a P-velocity decrease of 1.5 |$\pm$| 0.1 per cent | Dehydration melting of a Mesozoic Oceanic plate | Guohui et al. (2019) |
| 33 | Eastern South China | P wave triplications | 20–57 km thick LVL with a lateral variation | Related to Pacific Plate subduction, based on melt fractions estimates | Ma et al. (2020) |
| 34 | Colorado Plateau US | P RFs | Low velocity regions having −1.8 per cent low average amplitude compared to Z component | Dehydration melting, supports water filter model at a small scale | Zhang & Dueker (2020) |
| 35 | Northern South China Sea | P wave triplications | 2.0–2.5 per cent decrease in P-wave velocity | Partial melting induced by upwelling MTZ materials, hydrated by water released from stagnant slab | Li et al. (2020) |
| 36 | NW Pacific Subduction Zone | P & S wave triplications | |$\sim$|55–80 km thick low velocity layer | Melts caused by hydrous stagnant slab | Han et al. (2021) |
| 37 | Yellowstone US | P RFs | 10–50 km LVL above 410 km discontinuity | Water release, phase transformations induced by the descent of a Farallon slab fragment and ascent of deeply rooted Yellowstone plume | Frazer & Park (2021) |
| 38 | Western Junggar | P and SH triplications | 29 km thick LVL with a reduction of 5.6 per cent in SH and 4.4 per cent in P velocity. | Upwelling through a slab window due to mid-oceanic ridge subduction or self-buoyancy | Li et al. (2022c) |
| 39 | Qiangtang Terrane | P wave triplications | 36 km thick LVL with a P velocity drop of 2 per cent | Hydrous partial melt affected by dehydration and temperature | Li et al. (2022a) |
| 40 | Western Central Asian Orogenic Belt | P and sP triplications | 21–23 km thick LVL, with a P-wave velocity drop of 5.7–5.8 per cent | Partial melting induced by water and/or other volatiles released from the subducted Paleo Asian oceanic slab | Li et al. (2022b) |
| 41 | North-Central Pacific Ocean | SS precursors | Dehydration induced partial melting | Sharp interface (|$\le$|10 km at 0.5 Hz) | Frazer & Park (2023) |
| S.N. . | Region . | Method . | Finding . | Cause . | Reference . |
|---|---|---|---|---|---|
| 1 | East of southern Africa | S RFs | Observed intermittently between 280 and 360 km depth | Dehydration melting due to thermal plume, causal relation with large volume of flood basalts | Vinnik & Farra (2002) |
| 2 | Arabian plate | P & S RFs | 350–410 km deep, absent beneath Gulf of Aden | Marks separation of dry mantle root of Arabian Plate from the wet underlying mantle | Vinnik et al. (2003) |
| 3 | NW US | S wave triplications | 20–90 km thick intermittent LVLs with 5 per cent drop in shear wave velocity | LVLs possibly linked to Farallon Plate subduction and backarc extension | Song et al. (2004) |
| 4 | Yellowstone Hotspot US | P RFs | At 380 km depth | Release of water from mantle flux across 410 km | Fee & Dueker (2004) |
| 5 | Eastern Mexico | P & S wave triplications | 50 km thick LVL above 410 km discontinuity | Partial melting induced by water release from the transition zone | Gao et al. (2006) |
| 6 | Japan (Northern Honshu Slab) | P wave triplications | Excess temperature of 200 K and <1 per cent melt can explain the LVL | Thermal origin, partial melting | Obayashi et al. (2006) |
| 7 | Northern Rocky Mountains | P RFs | |$\sim$|22 km thick layer with 8.9 per cent shear wave velocity reduction | Dehydration melting due to difference in water content in the MTZ and overlying mantle. Affirms water filter model | Jasbinsek & Dueker (2007) |
| 8 | Tasman and Coral Seas | ScS reverberations | At |$\sim$|352 km depth, atop the 410 km discontinuity | Partial melting resulting from volatile induced melting | Courtier & Revenaugh (2007) |
| 9 | SW US (Tucson) | Electro-Magnetics | Intermittent, not a global feature, 5–30 km thick layer atop 410 km discontinuity | Dehydration melting. Supports water filter model | Toffelmier & Tyburczy (2007) |
| 10 | Global | S RFs | |$\sim$|350 km depth | Association with Mesozoic/Cenozoic mantle plumes, dehydration of water bearing silicates. Contradicts water filter model | Vinnik & Farra (2007) |
| 11 | Kalahari Craton (Africa) | P & S RFs | 300–350 km depth | Remains of a giant basaltic reservoir that formerly fed the flood basalts or the ceiling of a layer of dense molten silicates generated by transformations above 410 km | Wittlinger & Farra (2007) |
| 12 | Japan (Oceanward Honshu Slab) | ScS rever-berations | 50–75 km thick layer at an average depth of 356 km | Partial melt entrained from above by subduction or produced in situ by combined effects of water and temperature | Bagley et al. (2009) |
| 13 | California US | S RFs | |$\sim$|2 per cent reduction in S velocity | Dehydration melting due to difference in water solubility across 410 km, observed in the vicinity of hot spot | Vinnik et al. (2010) |
| 14 | Global | P RFs | Observed globally, no particular affinity to a particular tectonic environment | Weaker water storage capacity of mantle minerals may induce partial melting of water-bearing silicates throughout | Tauzin et al. (2010) |
| 15 | NW Canada | P & S RFs | |$\sim$|36 km thick layer with an S velocity contrast of −7.8 per cent at a nominal depth of |$\sim$|340 km | Possibly dense, hydrous, silicate melt ponding over the 410 km discontinuity | Schaeffer & Bostock (2010) |
| 16 | SW part of North America | P RFs | 4.6 per cent shear velocity reduction | Melt layer. Supports transition zone water filter model | Jasbinsek et al. (2010) |
| 17 | Western US | P RFs | 25–60 km thick layer above 410 km discontinuity | Partial melt resulting from upwelling of hydrated mantle due to water solubility contrast across 410 km | Schmandt et al. (2011) |
| 18 | Western US | P RFs | 19.1 to 98.8 km thick layer at 350 km depth | Increased water content due to oceanic material accumulated in the last 100 Myr. | Tauzin et al. (2013) |
| 19 | Hawaii | P RFs | Layer at |$\sim$|355 km depth | Combined effects of water and temperature | Huckfeldt et al. (2013) |
| 20 | Central Mexico | P RFs | LVL atop 410 km discontinuity. Seen on the continental side where the slab pierces 410 km | Hydration due to interaction of the subducted slab with the 410 km | Pérez-Campos & Clayton (2014) |
| 21 | Gibraltar Arc | P & S RFs | An intermittent, |$\sim$|50 km LVL atop 410 km near the Atlantic margin | Water release and melting atop 410 km discontinuity | Morais et al. (2015) |
| 22 | Afar Triple Junction | P RFs | Stable melt layer atop 410 km | Hydrous upwelling creating melt layer atop 410 km | Thompson et al. (2015) |
| 23 | Ibero-Maghrebian region | P RFs | Presence of low velocity layer atop 410 km | Increase in water concentration in the TZ due to dehydration of a stagnant slab | Bonatto et al. (2015) |
| 24 | Japan Subduction Zone | P RFs | Intermittent LVZ atop the 410 km discontinuity | Dehydration melting, interactions between subducted slab and surrounding mantle | Liu et al. (2016) |
| 25 | Western US | P RFs | 25–70 km thick LVL with a 1.6 per cent reduction in shear wave speed | Compositional heterogeneity, caused by release of volatiles from the subducted Farallon slab | Hier-Majumder & Tauzin (2017) |
| 26 | NW Pacific and the margin of Eastern Asia | P RFs | 50 km thick layer atop 410 km with a −2 to −4 per cent low shear wave velocity, global feature | Compositional heterogeneities | Tauzin et al. (2017) |
| 27 | SE Tibetan Plateau | P wave triplications | 20–40 km thick LVL with a P-wave velocity reduction of 5.3 to 4.3 per cent | Partial melting induced by water and/or other volatiles released from subduction of the Indian Plate and the stagnant Pacific Plate | Li et al. (2017) |
| 28 | Pacific Ocean | SS precursors | Lateral variation, global presence | Partial melting due to dehydration of ascending mantle | Wei & Shearer (2017) |
| 29 | SE Asia | P RFs | |$\sim$|30–50 km thick LVL atop 410 km at |$\sim$|368 km depth | Water induced melt layer related to earlier subductions | Wölbern & Rümpker (2018) |
| 30 | European Alps | P RFs | Observed near Alpine Orogeny | Upwelling of water rich rocks from MTZ in response to downwelled materials from the orogeny | Liu et al. (2018) |
| 31 | Northern Anatolia | P RFs | Evidence for Low-velocity zones above the 410 km discontinuity | Hydration of the MTZ from the Tethys/Cyprus slab and upward convection of MTZ material into the upper mantle | Taylor et al. (2018) |
| 32 | NE part of South China Sea | P wave triplications | 92.5 |$\pm$| 11 km thick LVL with a P-velocity decrease of 1.5 |$\pm$| 0.1 per cent | Dehydration melting of a Mesozoic Oceanic plate | Guohui et al. (2019) |
| 33 | Eastern South China | P wave triplications | 20–57 km thick LVL with a lateral variation | Related to Pacific Plate subduction, based on melt fractions estimates | Ma et al. (2020) |
| 34 | Colorado Plateau US | P RFs | Low velocity regions having −1.8 per cent low average amplitude compared to Z component | Dehydration melting, supports water filter model at a small scale | Zhang & Dueker (2020) |
| 35 | Northern South China Sea | P wave triplications | 2.0–2.5 per cent decrease in P-wave velocity | Partial melting induced by upwelling MTZ materials, hydrated by water released from stagnant slab | Li et al. (2020) |
| 36 | NW Pacific Subduction Zone | P & S wave triplications | |$\sim$|55–80 km thick low velocity layer | Melts caused by hydrous stagnant slab | Han et al. (2021) |
| 37 | Yellowstone US | P RFs | 10–50 km LVL above 410 km discontinuity | Water release, phase transformations induced by the descent of a Farallon slab fragment and ascent of deeply rooted Yellowstone plume | Frazer & Park (2021) |
| 38 | Western Junggar | P and SH triplications | 29 km thick LVL with a reduction of 5.6 per cent in SH and 4.4 per cent in P velocity. | Upwelling through a slab window due to mid-oceanic ridge subduction or self-buoyancy | Li et al. (2022c) |
| 39 | Qiangtang Terrane | P wave triplications | 36 km thick LVL with a P velocity drop of 2 per cent | Hydrous partial melt affected by dehydration and temperature | Li et al. (2022a) |
| 40 | Western Central Asian Orogenic Belt | P and sP triplications | 21–23 km thick LVL, with a P-wave velocity drop of 5.7–5.8 per cent | Partial melting induced by water and/or other volatiles released from the subducted Paleo Asian oceanic slab | Li et al. (2022b) |
| 41 | North-Central Pacific Ocean | SS precursors | Dehydration induced partial melting | Sharp interface (|$\le$|10 km at 0.5 Hz) | Frazer & Park (2023) |
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