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April, 14, 1909 Taiwan earthquake 9 deaths, 51 injured, 122 houses destroyed, 252 half destroyed, 798 damaged 25 ° , 121.5 ° Taihoku (1936) 24 ° , 123 ° H=80 km, M=7.3 Gutenberg Richter (1954) Hsu(1971) used 25 ° , 121.5 ° , H=80 km, M=7.3
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April, 14, 1909 Taiwan earthquake • 9 deaths, 51 injured, 122 houses destroyed, • 252 half destroyed, 798 damaged • 25°, 121.5°Taihoku (1936) • 24°, 123°H=80 km, M=7.3 Gutenberg Richter (1954) • Hsu(1971) used 25°, 121.5°, H=80 km, M=7.3 • Work in progress with Kuo-Fong Ma and Willie Lee
Taihoku report Plus: Taihoku S-P 7.8s Keelung S-P 6.0 or 7.4 s Wang et al., 2011
Relocation S-P times of Taihoku Observatory, WHKL structure 25.1°, 121.38°, H=50 km JLOC Relocation 25.23°, 121.38°, H=72 km Taipei
Available seismograms Hongo Omori, tromometer Mizusawa Omori Nagano Omori GöttingenWiechert Strasbourg Wiechert Hamburg Wiechert DebiltWiechert, Bosch
3 pairs of deep and shallow earthquakes 2001 Geiyo H=47.4 km Mw=6.8 2000 Tottori H=15km Mw=6.7 Recorded at TATO (Taiwan) 2008 Iwate H=98.8km Mw=6.8 2008 Iwate-Miyagi H=12km Mw=6.9 Recorded at TATO (Taiwan) 2004 Taiwan H=102.1 km Mw=6.6 2001 Taiwan H=16.0km Mw=6.8 Recorded at TTO (Japan)
1909 Taiwan, Hongo, Omori, “Bido” T0=12.5s, V=120, h=0.2 S P 3 cm 3/24/2001 Geiyo H=47.4, Mw=6.8, TATO S P 13 cm 10/6/2000 Tottori H=15.0, Mw=6.7, TATO S P 70 cm 300 s
1909 Taiwan, Hongo, Omori, “Bido” T0=12.5s, V=120, h=0.2 S P 3 cm 7/23/2001 Iwate H=98.8, Mw=6.8, TATO P S 4 cm 6/13/2000 Iwate-Miyagi H=12.0, Mw=6.9, TATO S P 40 cm 300 s
1909 Taiwan, Hongo, Omori, “Bido” T0=12.5s, V=120, h=0.2 S P 3 cm 10/15/2004 Taiwan H=102.1, Mw=6.6, TTO P S 1.4 cm 12/18/2001 Taiwan H=16.0, Mw=6.8, TTO 16 cm P S 300 s
1909 Taiwan, GӧttingenWiechert EW V=158, T=13.6, Ɛ=4.0 1 cm P group (p-p amp. =1 mm) W S group (p-p amp.=3 mm) E surface wave M (p-p amp.=4 mm) 3 min
2001 Geiyo H=47.4 km Mw=6.8 2000 Tottori H=15km Mw=6.7 2004 Taiwan H=102.1 km Mw=6.6 2001 Taiwan H=16.0km Mw=6.8 p-p amp.=8 mm p-p amp.=1.1 mm p-p amp.=45 mm p-p amp.=60 mm 2008 Iwate H=98.8km Mw=6.8 2008 Iwate-Miyagi H=12km Mw=6.9 p-p amp.= 7 mm p-p amp.=54 mm
1909 Taipei W4 model (Kao, Shen and Ma, 1998) W4 W4 model δ=33°, λ=128°, φ=29° H=70 km Mw=6.5
July 23, 2008 Iwate, Mw=6.8 7/23/2008, Mw=6.8 H=98.8 km sideview
1909 Taipei W4 and Down-dip extension model down-dip extension model W4 model δ=20°, λ=-90°, φ=90° H=70 km Mw=6.5 δ=33°, λ=128°, φ=29° H=70 km Mw=6.5
1909 Taiwan, GӧttingenWiechert EW V=158, T=13.6, Ɛ=4.0 1 cm P group (p-p amp. =1 mm) W S group (p-p amp.=3 mm) E surface wave M (p-p amp.=4 mm) 3 min 1909 Taiwan model, Mw=6.5, H=70 km P group S group surface wave Down-dip tension model p-p amp=1.9 mm W4 model p-p amp=2.1 mm
1909 Taiwan, Hongo, Omori, “Bido” T0=12.5s, V=120, h=0.2 S P 3 cm 1909 Taiwan model, Mw=6.5, H=70 km Down-dip Extension model p-p amp. = 1.9 cm W4 model p-p amp. = 3.3 cm 300 s
July 23, 2008 Iwate, Mw=6.8 H=98.8 km, Moment-rate spectrum Moment, 1013 N-m
Ground motion from an intermediate depth earthquake, Iwate, Japan, Mw=6.8, H=98.8 km Spectral velocity Spectral acceleration
March 24, 2001 Geiyo, Mw=6.8, H=47.4 km, Moment-rate Spectrum Moment, 1013 N-m
Ground motion from an intermediate depth earthquake, Geiyo, Japan, Mw=6.8, H=47.4 km Spectral velocity Spectral acceleration
Conclusion The 1909 Taipei earthquake: most likely location, 50 to 100km just beneath Taipei. Magnitude: Mw=6 1/2 to 6 3/4. Probably an intraslab event and suggests that the slab beneath Taipei is capable of generating significant events. Intraslab events in other places are enriched in high frequency with strong ground shaking. In case of Taipei, Taipei basin response must be convolved. Intraslab events can be as large as Mw 8.