Eminar R Imaging fluids in the crust: seismological and volcanological applications
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Eminar https://www.mtnet.info/EMinars/EMinars.html Imaging fluids Prof. Yasuo in the crust: Ogawa seismological Registration 07 July 2021 08:00 R Tokyo Institute and link of Technology volcanological applications July 7th, 17:00 Japanese Local Time
Imaging fluids in the crust: seismological and volcanological applications Yasuo Ogawa Volcanic Fluid Research Center Tokyo Institute of Technology Date Time: Jul 7, 2021 08:00 Universal Time UTC
Outline • Review on our magnetotelluric studies • Seismology targets • Intraplate earthquakes • Plate interface at subduction zones • Volcanology targets • Imaging Geothermal system • Temporal resistivity changes
Seismology targets • Intraplate earthquakes • Active faults, shear zones, fluid reservoir, deformation • NE-Japan • North Anatolian Fault(NAF) • NZ • Volcano-Earthquake link • Plate interface at subduction zones • NZ • SW Japan
that the continued predominance of rupturing on steep reverse faults release and solute transport from approxim Fault Valve model throughout NE Honshu necessarily involves local accumulation of fluid-overpressure to near-lithostatic values. mogenic zone (Fyfe et al., 1978; Ague et al., 19 fracture systems may then be reduced by h Fig. 2. Hypothetical frictional strength profiles in relation to fluid-pressure regimes in a fault zone: (a) Hydrostatic fluid-pressures throughout ‘Hydrostatic–Byerlee’ strength profile; (b) Compartmentalised fluid overpressure in the fault zone (postfailure profiles assume a rupture transectin Sibson et al (1988, Geology) Sibson (2009, Tectonophysics)
Pore pressure, Rheological properties at the Brittle-Ductile Transition BDT Sealed by Silica solubility breakdown @400 deg C (Saishu et al, 2014, Terra Nova) Fig. 2. Hypothetical frictional strength profiles in relation to fluid-pressure regimes in a fault zone: (a) Hydrostat Wannamaker et al strength profile; (b) Compartmentalised ‘Hydrostatic–Byerlee’ Sibson fluid overpressure in the fault zone (postfailure profil (2009, Nature) (2009, Tectonophysics)
NE Japan • Volcanic arc • Reactivated fault • Flow supply from the slab Sibson (2009, Tectonophysics)
mechanisms (e.g., Ha- The evolution of late Neogene tectonics in northern Honshu can be effectively subdivided in three main stages: (i) a period NE Japan eparated from the Eur- ting in early Miocene Tectonic background of widespread extensional deformation of early Miocene age; (ii) a period of relative tectonic quiescence of late Miocene tenuation of northern ning of the adjacent Neogene time this do- ormation which led to folds. However, evi- Reverse faulting is well preserved in ematic attenuation to- Using the existing faults al., 2001). Honshu, pre-Neogene y complex locally in- Inversion tectonics tensively crop out in rgin of the Kitakami er anomaly gradient c structure. The distri- sediments is bounded e structural expression g normal fault system Normal faulting e normal fault system, Japan Sea Opening in Miocene ection profiles, gravity al information, is de- tions. y Miocene extensional km along the western efined as the Kitakami he early Miocene vol- n edge of the Miocene Fig. 2. Neogene tectonic evolution of Northern Honshu modified after Sato , 1989; Tatsumi et al., and Amano (1991). VF: volcanic front, TR: trench axis, KFS: Kitakami fault system.
NE Japan • Volcanic arc • Reactivated fault • Flow supply from the slab Sibson (2009, Tectonophysics)
NE Japan (1) Kitayuri-Senya M7.1 M7.2 13 (Ogawa et al.,2001,GRL)
NE Japan (1) Kitayuri-Senya Japan Kitak ami Dewa Hills Yok ote Basin Ou Back bone R an ge Sea Lowlan d Kitayuri Thr ust F Senya F KLWB F V.E. = 1.0 10000 De pth(km) 10 C2 1000 6. 6km/s C1 C3 100 20 Moho C4 10 30 7.6 -7 .7km/s 1 m -40 -20 0 20 40 Distance(km) High seismicity at the rim of the mid-crustal conductors (Ogawa et al., 2001,GRL) Starts: Seismic reflectors 14
Hypocenter region of NE Japan (2) Northern Miyagi 1962 Northern-Miyagi Earthquake (Mitsuhata et al., 2001, GRL) Seismicity above the conductor 15 Cutoff depth of seismicity = top of conductor
North Anatolian Fault, Turkey Seismic GAP 16 Kaya (2012, PhD Theis)
Compilation of NAF 2D profiles Along strike variation Segmentation “Asperities” as “resistors” Kaya et al. (2013, Geophys. J. Int)
3d inversion result Depth:-11.714 Depth:-11.714 km km Depth:-5.207 Depth:-5.207 km km 4040 44 4040 “seismic gap” as a resistor 4 4 Northing (km) Northing (km) (km) 2020 2020 (km) 0 0 Depth:-5.207 km 22 0 0 Depth:-11.714 Depth: -12 kmkm Ωm2 2 Northing 40 4 Northing 40 -20 -20 4 -20 -20 (km) (km) 20 20 -40 -40 00 -40 -40 00 0 -60 -60 2 0 -60 -60 2 Northing Northing -20-60 -60-30 -30 0 0 303060609090 -20-60 -60-30 -30 0 0 303060609090 -40 Easting Easting (km (km ) ) 0 -40 Easting Easting (km (km ) ) 0 -60 -60 -60 -30 0 30 60 90 -60 -30 0 30 60 90 Easting (km ) Easting (km ) Depth: -20 km Depth:-19.955 Depth:-19.955 km km Ωm Depth: -44 km Depth:-44.112 Depth:-44.112 km km Ωm 4040 44 4040 44 Northing (km) Northing (km) (km) 2020 2020 (km) 0 0 Depth:-19.955 km 22 0 0 Depth:-44.112 km 22 Northing 40 4 40 4 Northing -20 -20 -20 -20 (km) (km) 20 -40 20 -40 00 -40 -40 00 0 -60 -60 2 0 -60 -60 2 Northing Northing -20-60 -60-30 -30 0 0 303060609090 -20-60 -60-30 -30 0 0 303060609090 -40 Easting Easting (km (km ) ) 0 -40 Easting Easting (km (km ) ) 0 -60 -60 -60 -30 0 30 60 90 -60 -30 Kaya 0 30(2012, PhD Theis) 60 90
South Island, New Zealand Murchison EQ Early 20th Century M>7 Wannamaker et al. (2009, Nature) 19
Wannamaker et al. (2009, Nature) 20
Wannamaker et al. (2009, Nature) 21
Volcano-Earthquake Link Morioka Sendai Tokyo • 2008 Iwate-Miyagi Nairiku Earthquake (M7.2) 22
alldata800s5_model.02 : z=10km:9.8km to 13km: EQ;+−2km 30 4 alldata800s5_model.02 : z=5km:4.3km to 5.6km: EQ;+−2km 30 4 iwatemiyagi_Ichihara_Mishina_model.final : z=5km:4.3km to 5.6km: EQ;+−2km 10km depth 5km depth 30 3.5 4 20 3.5 20 3.5 20 3 Kurikoma Volcano C2 3 3 10 10 2.5 10 distance(km) N+ 2.5 2.5 distance(km) N+ distance(km) N+ 0 2 0 C1 0 2 2 1.5 1.5 1.5 −10 −10 −10 C3 1 1 1 −20 −20 −20 0.5 0.5 0.5 10km −30 10km 0 −30 0 −30 −30 −20 −30 −10 −20 0 −10 0 distance(km) E+ 10 10 20 20 30 log10Ωm 0 30 −30 −20 −10 0 distance(km) E+ 10 20 30 distance(km) E+ RMS=1.53 Red star:The epicenter Aftershocks @ Resistive area Black circles: Aftershocks (Okada et al.(2009)) @5km:C1 @ Kurikoma volcano Student Version of MATLAB C2@ low seismicity zone Student Version of MATLAB Student Version of MATLAB @10km: C1 & C2 connected (volcano-hypocenter link) 23
Fluid branching Equi-resistivity surface (10Ωm) Hypocenter Fluid branching: (1) One to the volcano (2) The other to the hypocenter 24
Co-, post-seismic slips and resistivity distribution on the fault planes Coseismic N Postseismic logΩm N alldata800s5_model.02 : z=5km:4.3km to 5.6km: EQ;+−2km 4 Slip Slip 30 4 3.5 20 R1 C2 3 3 10 2.5 distance(km) N+ 0 2 2 C1 R2 1.5 −10 1 1 −20 R1 0.5 10km 10km −30 0 0 (Contour line: Slip, Cont. Int.: 1 m) (Contour line: Slip, Cont. Int.: 4 cm) −30 −20 −10 0 distance(km) E+ 10 20 30 Co-seismic slip corresponds Post-seismic slip corresponds to R1 (asperity) either to R or C Postseismic slips are caused by static stress change or pore pressure change (Iinuma et al., 2009)
Seismology targets • Intraplate earthquakes • Active faults, shear zones, fluid reservoir, deformation • NE-Japan • North Anatolian Fault(NAF) • NZ • Volcano-Earthquake link • Plate interface at subduction zones • NZ • SW Japan
Hikurangi subduction, NZ Observed data in 2015-2016 MT measurements in 2016-2017 at Transition zone from weekly- to strongly- coupled. Heise et al (2019, EPSL)
Comparison between areal strain rate and resistivity at the plate interface Initial model Best fit model Heise et al (2019, EPSL) Subducting Plate fixed: 5 km below the plate interface
Philippine Sea Subduction, SW Japan Study Area (Obara and Kato et al., 2016)
Philippine Sea Subduction, SW Japan depth : 3km depth : 5km R1 C2 C1 50km R1 depth : 10km depth : 20km C2 R1 C2 R1 C1 C1 PHS depth : 30km depth : 40km R1 PHS PHS log10Ωm
Philippine Sea Subduction, SW Japan 10km depth NW SE C1 R1 C2 R1 Three NNW-SSE profiles c k ed Lo Non-volcanic tremor (white dots) are located above the place, adjacent to the large silicic consolidated magma body. R1 Kinoshita (2018, M.Thesis) o c ked 50km L
Philippine Sea Subduction, SW Japan If the plate is not constrained Kinoshita (2018, M.Thesis)
Volcanology targets Imaging Magma pathways Imaging Geothermal system • Clay cap • Silica Cap • Super Critical Fluids below the BDT Temporal resistivity changes • Magnetotelluric monitoring • Controlled source monitoring (EM-ACROSS)
Kusatsu-Shirane Volcano, Japan Objective Understanding the phreatic eruption architecture in particular for the 2014 unrest [edifice inflation / seismicity / increased lake temperature/ increased magmatic gases] Kusatsu-Shirane by 3D resistivity distribution to 2~3km depth Volcano using 91 MT/AMT sites Key Words: Phreatic eruption, Clay Cap, Brine, Supercritical Fluid Final Paper Number: GP006-06 Session Date and Time: Tuesday, 15 December 2020; 04:00 - 05:00 PST
り検知能力が下がっている。 2014 Volcanic Unrest Daily Seismicity 月(JMA, 24 日 149 回 2016) 100 Inflation period Point source analysis for 2014 Jan to 2016 May Obs Cal East Down KSE(EW) Or North Down Inflation period KSW(NS) KSW(EW) East UP KSS(EW) Or KSE(NS) North Up KSS(NS) 2014 2015 2016 • Source Depth at 1500m(ASL): 500m below surface 35 Terada et al.(2016) • Total volume 1.2×105 m3
MAP@1400mASL(600m below surface) S-N Section FEMTIC code: Usui et al. (2017, GJI) Unstructured tetrahedral meshes C1: Bell-Shaped Clay Cap Rock C2: Columnar fluid path C3: Brine (Super Critical Fluid) Seismicity: dots Mag- Demag sources: starts Inflation source: X W-E Section 3D View from SW
Phreatic eruption architecture C1: Clay cap (400 degC) : Super-Critical Fluid Capped by Silica Episodic magmatic gas flux through the brine (C3) broke the silica cap and induced seismicity, migration of vapor and inflated the edifice under the clay cap (C1) Tseng, Ogawa, Nurhasan et al. (2020, EPS) doi.org/10.1186/s40623-020-01283-2, Modified from Hutnak et al. (2009, JGR)
Silica Seal at Brittle-Ductile Transition (~400 degC) Sealing by low-solubility of silica Saishu et al. (2015, Tera Nova) 38
Formation of Brine Lenses shown in Fig. 5. We used to calculate the conducti and Archie’s law to acco trix, see Supplementary m Afanasyev et al. (2018, EPSL) The central part of th culated electrical resistivi 1 !·m). A vapour-rich re is clearly seen at the mo (Fig. 8b). As the lens coo the resistivity distribution The transition between t fluid remains sharp becau increases fluid conductivi served on MT images on degassing. 6. Discussion and conclu Our modelling results way for a rapid ascent o for brine lens formation. ther static permeability d conduit (our model) or dy fluid ascent (Weis, 2015) of the brine lenses whos phase transitions, althoug ologically realistic. The br ascending supercritical flu upper surface by halite p We show that brine l system in which fluids a overlying rocks whose pe meable column within le is likely beneath any vo With a conduit, brine lenses can be formed at 2-4km depth. Fig. 8. Temporal evolution of (a) bulk salinity and (b) electrical resistivity follow- ing abrupt cessation of degassing for the reference scenario in Fig. 5. Time (t ∗ ) is that case the permeable duit system, now filled given as kyr since cessation of degassing. Symbol v as in Fig. 6. Isotherms contours and solidified magma and are every 25 ◦ C. Electrical resistivity is calculated as described in Supplementary material, for direct comparison to Fig. 1. Note equivalent colour scale in the range ated host rock damage z Brine can stay for 250 kyr. 1–104 ! ·m in Fig. 1 and Fig. 8b. develop under a wide ran favoured in the followin precipitates, but even at t ∗ = 750 kyr after the cessation of de- relatively high, i.e. at or gassing a large salinity anomaly persists at 3 to 4 km depth. Thus, (∼670 ◦ C); the salinity o 39 though a focussed (local the permeability decrease with depth is an important feature of our models, that, in contrast to Gruen et al.’s (2014) adoption of fective radius.
1,000 µm Porphyry model 15.0 kv BSE 10 µm UoB-ES 24/10/2013 WD 11.0 mm 15 :14 : 53 Blundy et al (2015) Figure 3 | Comparison of experimental and natural mineralization textures. a, Reflected-light photomicrograph of chalcopyrite (cp) and minor magnetite Stage (mt)1:mantled by anhydrite (an) within vesicle in dacite porphyry from the potassicStage alteration 2: zone, Don Manuel PCD prospect, Chile. The rock’s matrix is Slowcomposed process of finely crystalline plagioclase (An51 ), biotite, oxides, pyrite and apatite. The bulk composition is almost identical to the felsic experimental to create brines for 10k-100k years. Gas from the mafic magma interact with the starting material. b, Detail from run product M4 (Fig. 1) showing digenite (white) with a thin corona of magnetite (pale grey) filling a vesicle (black) in brine partially crystalline dacite. Additional run products listed in Supplementary Table 1. Scale bar is 10 µm. a Lava dome b Phyllic Silicic magma alteration with crystals Mafic magma Volcanic rocks Supercritical gas with crystals Low-salinity vapour Sulphur-rich gas Brine Copper sulphide Vapour flow Brine Host rocks Gas flow Gas flow Potassic alteration Phyllic alteration 2–4 km Brine + vapour Silicic Gas 6–10 km Mafic Figure 4 | Gas–brine reaction model for PCD formation. a, Stage 1. Slow accumulation, crystallization and degassing of dacite magma beneath small dome volcano. Below 2–4 km depth exsolved gas is supercritical, condensing at shallower levels to brine, which becomes trapped and accumulates (driving potassic alteration of host rocks), and low-salinity vapour, which escapes upwards. b, Stage 2. Periodic destabilization of a deeper magmatic system releases mafic magmas and sulphurous gases that react with trapped brines, forming sulphide minerals at temperatures of 850 C. Mingling between mafic and silicic magmas may occur, but is not required. Hydrogen chloride produced by sulphide precipitation drives phyllic alteration in overlying rocks by feldspar hydrolysis below ⇠600 C. Unreacted sulphurous gases drive alteration in the shallow lithocap. 40
Volcanology targets Imaging Magma pathways Imaging Geothermal system • Clay cap • Silica Cap • Super Critical Fluids below the BDT Temporal resistivity changes • Magnetotelluric monitoring • Controlled source monitoring (EM-ACROSS)
Temporal resistivity changes • MT monitoring • Aizawa et al. (2011, JVGR) Sakurajima volcano • Peacock et al. (2013, Geophysics) , Thiel (2017, Surv Geophys) EGS • Hill et al.(2020, GRL) Tongariro eruption, NZ • Controlled source monitoring • Tseng et al. (2020, PhD thesis) EM-ACROSS
Sakurajima Volcano, Japan: resistivity monitoring by MT Aizawa et al. (2011, JVGR)
Resistivity change in response to tilt: Ground water migration? r(Volcanic fluid) < r(ground water) ra (22.5Hz) @HARMT near (2km) the vent r(Volcanic fluid) > r(saline ground water) ra (97Hz) @KURMT far (4km) from the vent near the shore Tilt record: “start of the magma intrusion” Limited number of sites (2) Limited impedance components Limited frequencies Aizawa et al. (2011, JVGR)
2012 eruption of Mount Tongariro, NZ (Hill et al., 2020, GRL) MT survey (・2008 ‒ 2010) Before the phreatic eruption from T(Te Maari) crater Te Maari eruption in Nov 2012 Repeat MT survey (・June 2013) After the phreatic eruption from T(Te Maari) crater
Conductive brine was lost after the phreatic eruption
Summary • Review on our magnetotelluric studies • Seismology targets • Intraplate earthquakes • Plate interface at subduction zones • Volcanology targets • Imaging Geothermal system • Temporal resistivity changes ... Challenging topic MT removal of galvanic distortion (which can also vary with time) temporal alignment error (magnetic sensor) quest for high quality data Controlled source EM
Thank you very much for your attention! Yugama Crater, Kusatsu-Shirane Volcano, Jap
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