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
Iio-Kobayashi Model (2002)
Iio & Kobayashi (2002, EPS)
Iio-Kobayashi
Model (2002)
Iio & Kobayashi (2002, EPS)
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)
Japan Sea Rifting
@Miocene 14Ma
Rifting
Normal Fault system
Ofofuji et al. (1985, Nature)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 14Hypocenter 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 conductorNorth 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 90South Island, New Zealand
Murchison EQ
Early 20th Century
M>7
Wannamaker et al. (2009, Nature) 19Wannamaker et al. (2009, Nature) 20
Wannamaker et al. (2009, Nature) 21
Volcano-Earthquake Link
Morioka
Sendai
Tokyo
• 2008 Iwate-Miyagi Nairiku Earthquake (M7.2)
22alldata800s5_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)
23Fluid branching
Equi-resistivity surface (10Ωm)
Hypocenter Fluid branching:
(1) One to the volcano
(2) The other to the hypocenter
24Co-, 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 log10ΩmPhilippine 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
LPhilippine 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 m3MAP@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 SWPhreatic 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)
38Formation 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.
40Volcanology 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 EMThank you very much for your attention!
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