Transcript Japan__NZ_Webinar_summary.Bangs

SZO – Webinar
Organizers:
Yoshi Ito
Yoshi Tamura
Susan Ellis
Nathan Bangs
New Zealand and Japan
OVERVIEW OF NEW ZEALAND SUBDUCTION
-
NEW ZEALAND
TECTONICS
Hikurangi subduction
Taupo Volcanic Zone
and rift [most productive
rhyolitic system on earth;
magma-tectonic interactions]
-
Puysegur subduction
zone and Fiordland [juvenile
subduction zone, caught in the act
of initiation; root zone of an ancient
arc]
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Havre trough and
Kermadec arc [undersea
silicic magmatism; volatile fluxes in
back- arc setting; along-striie
changes in sediment input]
Bathymetry from NIWA
See also a summary of
relevant literature
https://www.iris.edu/hq/works hops/2016/09/szo_16
1. Tectonic overview
GNS Science
Key Opportunity:
Locking on interface and its relationship
to slow slip along the Hikurangi Margin
Wallace et al. 2004 (JGR)
Douglas et al., 2005 (GRL)
Wallace and Beavan, 2010 (JGR)
Wallace et al., 2012 (JGR)
Bartlow et al., 2014 (JGR)
Wallace et al., 2016 (Science)
2. Strain accumulation on subduction interface
GNS Science
Key Opportunity:
Along-strike margin transitions
Southern
segment
(Wairarapa)
Central
segment
(Hawke's Bay)
Northern
segment
(Raukumara)
INCREASING SEDIMENT THICKNESS
D E C R E A S I N G S U B D U C T I O N FL UI D C O M P O N E N T
T E C TO N I C E R O S I O N
BACKARC EXTENSION
F R O N TA L A C C R E T I O N
CONTRACTION
SHALLOW W EDGE
STEEP W EDGE
•
geophysical evidence for high fluid •
content within upper plate
Figure 1: Oblique view of North Island with depth contours of
subducting Pacific Plate (blue dashed lines) , convergence rates
at the Hikurangi Trench (red arrows), and locked (red) vs.
slipping interface. Black dashed line marks approximate location
of the change from locked to slipping behaviour.
Key Opportunity:
Examine seamount subduction, highly reflective zones, wedge structure, and the
developments along the plate interface
Barker et al., 2009; Bell et al.,
2010; IODP proposal 781A
Ghisetti et al., 2016; Plaza-Faverola et al., 2016
MBIE proposal 2016
4. Transitions along-strike
GNS Science
Key science questions- Hikurangi
1.Why is there a transition in locking depth from shallow in north to deep in
south?
Fluids pressures? Composition of interface? Roughness of interface? Composition of upper plate?
Other reasons?
2.What is the maximum rupture dimension for a Hikurangi megathrust
earthquake?
North and south rupture together? How deep/shallow? Role of splay faults? Tsunamogenic potential?
3.What causes SSEs and do they trigger LFEs, tremor, micro or
macroseismicity (and vice-versa)?
7. Questions for discussion
GNS Science
FUNDED PROJECTS (International Collaborations) - SHALLOW SLOW SLIP PART
1:
IODP
riserless drilling proposal 781A and APL:
- Expedition 375 - sample sediment input section, downhole logs, install observatories
[main cruise scheduled March-May 2018]
- Expedition 372 – LWD [scheduled ~ Dec 2017]
3D seismic investigation of faults around 781A drilling transect: US (NSF), UK,
Japan, NZ; Jan/Feb 2018 [Bangs et al., Bell, Kodaira, Henrys, Mochizuki]
6. Ongoing projects
GNS Science
FUNDED PROJECTS - SHALLOW SLOW SLIP PART 2:
MBIE contestable research fund- $6.5M NZD (NZ research time, paleoseismology, modeling, rolling
seafloor geodesy, science in support of drilling and active source surveys: NZ, Japan, US) [PI Wallace, Henrys]
HOBITSS (NSF)- APG data published (Wallace et al., 2016), seismological data (OBS) in progress- [PI
Schwartz, Sheehan]
Fry- tremor
locations,
mechanisms
MBIE proposal- onshore/offshore sampling
6. Ongoing projects
HOBITSS OBS data- Erin Todd- (WIP)
GNS Science
FUNDED PROJECTS- MEGATHRUST BEHAVIOR variations along-strike
MBIE fund (see last page)- paleoseismological part will analyse offshore (turbidites) [Barnes et al.]
and onshore (paleoseismic record) [Cochran, Clark]
SHIRE: integrated earth systems NSF project. Active source transects (McIntosh, van Avendonk,
Okaya) across and along-strike. Paleoseismology onshore (Marshall, Pilarczyk). Numerical
modeling (fluid-mechanical interactions, sediment underplating- 2D and 3D) (Saffer)
Land-based MT: GNS group [Opportunities for offshore MT]
NSF: time dependent inversions for slow-slip for Hikurangi and revise locking models [PIs Bartlow, Wallace];
Heatflow [PI Harris]
Marsden (NZ)- [PI Kaneko] Probing the Hikurangi subduction mega-thrust using full-waveform inversion
GNS MT group
data points
SHIRE IES proposal
6. Ongoing projects
GNS Science
There are many potential New Zealand partners
GeoNet
New Zealand Earthquake Commission
Ministry of Business, Innovation and Employment
Royal Society of New Zealand
GNS Science
NIWA
Victoria University of Wellington
U. Of Auckland
Waikato University
University of Canterbury
Otago University
East Coast LAB (Life at the Boundary)-
funded by NZ government and regional councils
GNS Science
Japan Subduction Overview
ADer The headquarters for Earthquake Research
Promo/ o n hIp://jishin.go.jp
Key Opportunity – Nankai Trough:
Mechanical and hydrologic properties of faults within
the shallow forearc of a sediment-rich, accretionary margin
Recent & Ongoing Project: Nankai Trough
IODP Nanaki drilling
• KANAME(FY2009-2013)[PI:Gaku Kimura]
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Understanding overall framework of the Nankai Trough
subducion zone
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Revealing materials, and mechanical and hydrologic
properties of seismogenic faults
Construct i o n a n d verification of a comprehensive
model for pre-and co-seismic processes
–
• KAKEN-S(FY2015-2019)[PI: Gaku Kimura]
hIp://www-solid.eps.s.utokyo.ac.jp/nantro~en/gaiyo.html
Key Opportunity – Nankai Trough:
Slow earthquakes
Recent & Ongoing Project: Slow
Earthquakes
Science of Slow earthquakes(FY2016-2020)[PI: Kazushige
Obara]
From “Discovery” to
“Understanding” From “regional” to
“general understanding”
Key Opportunity – Japan Trench:
Shallow slip and its relation to the megathrust
Recent & Ongoing Project: Japan Trench
History of Shallow Megathrust events
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JDASH(FY2014-2018)[PI: Ryota Hino]
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Revealing past shallow seismic slip and deformation from high-resolut i o n s eismic survey
Invest i gating past megathrust events from tsunami turbidit e layers based on core samples from ultra-deep piston coring
near the Japan trench
Ident i f y postseismic deformation processes on the shallow fault by using dense arrays of broadband seismic and geodet i c
sensors
Mapping potent i a l f a u l t s o f o u ter-rise earthquakes
•
KAKEN-S(FY2015-2019)[PI: Shuichi Kodaira]
Sun et al.,
2014
Kodaira et al. 2012
Key Opportunity: Co-existance of fast and slow
rupture on the megathrust
Scientific Questions & New Opportunities
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What controls on fast and slow rupture mode, especially shallow portion ?
Why both fast and slow ruptures co-exist ?
What controls the migration speeds, or rupture speeds ?
Periodic SSE
Coexsistence with
fast and slow
ruptures
Variation of migration speeds, or
rupture from SSE to megathrust
Kato et al.., 2013
Uchida et al.., 2016
Ito et al.., 2013
Partners & International Collaborations
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JAMSTEC
NIED
AIST
JCG
JMA
GSI
Japanese Universities
Crust-Mantle
Connections
From Izu-Ogasawara
(Bonin) and Aleutian
Arcs to Kermadec Arc
Yoshihiko Tamura, Takeshi Sato, Toshiya
Fujiwara Shuichi Kodaira & Alexander Nichols
(JAMSTEC)
Seismic velocity image along the
volcanic front of the IzuOgasawara arcs obtained by
seismic refraction tomography
(Kodaira et al., 2007).
Rising mantle diapirs stall near the base of the oceanic crust at depths
controlled by the thickness of the overlying crust. Where the crust is
thin, melting occurs at relatively low pressures in the mantle wedge
producing andesitic magmas. Where the crust is thick, melting
pressures are higher and only basaltic magmas tend to be produced.
Key Opportunity: Examine relationship between
island arc composition and
crustal thickness
Seismic velocity image along the
volcanic front of the IzuOgasawara arcs obtained by
seismic refraction tomography
(Kodaira et al., 2007).
FUNDED PROJECTS- FLUIDS/MECHANICS
NSF: [PI Jaime Barnes] Fluid-mobile and volatile element (Cl, B, and Li) cycling through the forearc
(+Waikato): Shaun Barker -detecting fluid changes associated with SSEs, N Hikurangi
Sticky/Creepy Marsden [PI Ellis], will be continued under IES/MBIE: fluid chemistry and flowrates;
fluid flow, modeling
Agnes Reyes, in prep.
Ellis et al., 2015
6. Ongoing projects
GNS Science
Seismic tomography
Interface contours in depth
Williams et al., 2013
Onshore MT
Heise et al., 2013
NORTH
EberhartPhillips et
al., 2010,
2013; 2015
VpVs on interface
SOUTH
- Tomography: high Vp/Vs along
interface in north
- MT: electrically conductive
interface in north
4. Transitions along-strike
GNS Science
Scientific Quetions & New Opportunties
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What is next infrastructures and facilities to observe various phenomena on the plate interface ?
How do we evaluate real-time monitoring data to mitigate earthquake and tsunami disasters ?
GPS/A: Japan Coast
Guard