geophysical observations of the 100 km region around kamland tohru watanabe dept. of earth sciences...
TRANSCRIPT
Geophysical observations of the 100 km region around KamLAND
Tohru Watanabe
Dept. of Earth SciencesUniversity of Toyama (Japan)
Today’s Talk
1. Geophysical observations around KamLAND
2. Laboratory data on seismic velocities in rocks around KamLAND
Toyama
KamLAND
Niigata-Kobe Tectonic Zone (High strain-rate zone)
Atotsugawa Fault 1858 Hiestu Earthquake (M7)
Geophysical Observations Seismological Obs. MT surveys Gravity Obs.
1. Geophysical Observations
Iio et al. (2002) EPSL
Depth Contours of Pacific and Philippine Sea Plates
Nakajima et al. (2010)
KamLAND
NKTZ
Seismological Studies on Crustal Structure
Nakajima et al. (2010)
NKTZ
Iidaka et al. (2003)
Kato et al. (2006, 2007)
Nakajima et al. (2010)
Iidaka et al. (2003)
Seismic refraction survey
6 explosive sources
391 seismic stations
L~250 km
P-wave velocity structure (Iidaka et al., 2003)
N S
Toyama Plain (sediments)
KamLAND
Kato et al. (2006, 2007)
2006
2007
Travel-time Tomography
Explosive sources +Local Earthquakes
Nakajima et al. (2010)
P-wave velocity structure (Kato et al.,2007)
Toyama Plain (sediments)
Nakajima et al. (2010)
Nakajima et al. (2010)
Travel-time Tomography
P-wave velocity perturbationsD=0 km D=5 km D=10 km
D=15 km D=25 km D=40 km
Nakajima et al. (2010)
Structure along Atotsugawa Fault
Hakusan Tateyama
Nakajima et al. (2010)
Velocity Perturbations across Atotsugawa Fault
SN
Nakajima et al. (2010)
Summary of Seismological Observations
Seismological observations have revealed
(1) A complicated configuration of subducted plates
(2) Low velocity regions associated with active volcanoes
(3) Surface low velocity regions caused by thick sediments
2. Laboratory Data on Seismic Velocity
Upper, Middle Crust (D<10 km) Kagami and Watanabe (2009)
Surface rocks
Lower Crust (D>20 km) Nishimoto et al. (2008) Xenoliths (Rocks collected by magma
during its ascent)
Surface geology around KamLAND
after Yamada et al. (1989)
11 rock samples
P-wave Velocity vs Confining Pressure
D~7kmD~2km
Granodiorite (TKA-b1)
Density vs Vp (180MPa)Hida granites
Hida metamorphic rocks
Vs vs Vp (180 MPa)Hida granites
Hida metamorphic rocks
Comparison with Observed Velocity
Hida metamorphic rocks (+Hida granites)
Kato et al. (2007)
KamLAND
Ichino-megata
KamLAND
Ichino-megata mafic-ultramafic xenoliths
Lower Crust Xenoliths
Iio et al. (2002) EPSL
Nishimoto et al. (2008) (1) Hornblende gabbro (2) Hornblende-pyroxene gabbro (3) Amphibolite (4) Pyroxene amphibolite (5) Hornblendite
Measured Velocity at High T and High P
Nishimoto et al. (2008)
D~25 km
Inference of Lower Crustal Material
Nakajima et al. (2010)
D=25 km
Rock + aqueous fluids
D=25 km
Pyroxeneamphibolite
Hornblende-pyroxenegabbro
Nakajima et al. (2010)
Summary of Laboratory Data
Upper and middle crust Hida metamorphic rocks Hida granites
Lower crust Pyroxene amphibolite Hornblende-pyroxene gabbro
