Lateral Variations of Rayleigh-Wave Dispersions in the Philippine Sea Region

Chang, Wen‐Yen; Yu, G. C.; Hwang, Robert R.; Chiu, Jiou-Kwei

doi:10.3319/tao.2007.18.5.859(t)

Cited by 9 publications

(12 citation statements)

References 21 publications

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“…The phase velocity of the Rayleigh wave along the greatcircle path from the earthquake to the station was derived by the single-station method (cf., Hwang and Yu, 2005;Chang et al, 2007;Chang et al, 2010). Hence, the time it takes for the Rayleigh wave to travel from a source to a given station at period T can be written as follows.…”

Section: Data and Phase-velocity Measurementsmentioning

confidence: 99%

“…where C(T ) and t (T ) denote the phase-velocity and the corresponding travel time of a Rayleigh wave at a given period T , respectively; L is the epicentral distance; φ S R (T ) is the station phase after removing the instrumental response; φ 0R (T ) is the initial phase of the source, calculated from a known focal mechanism and the velocity structure of the source area; N is an arbitrary integer for detecting the reasonable phase-velocities in the long-period part (cf., Chang et al, 2007;Chang et al, 2010). Here, the focal mechanism (strike/dip/rake = 231…”

Section: Data and Phase-velocity Measurementsmentioning

confidence: 99%

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Rise time and source duration of the 2008 M W 7.9 Wenchuan (China) earthquake as revealed by Rayleigh waves

et al. 2011

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The fault parameters of the 2008 Wenchuan earthquake were studied in a rupture directivity analysis by simultaneously inverting the period of the rst Fourier spectral-node and the 100-s phase-delay time of the Rayleigh wave. The results show that the earthquake is a unilateral event with an optimal rupture azimuth of N59• E, consistent with the distribution of aftershocks. They also indicate that the fault plane strike is in the NE-SW direction, corresponding to the fault plane strike of 238• and NW-dipping (reported by the USGS). The inversion shows the source duration (including the rise time and rupture time) and rise time are 70±0.8 s and 9.3±0.6 s, respectively. The rupture velocity estimated only from the rupture time exhibits relatively higher value, 3.45±0.10 km/s, close to or larger than the S-wave velocity in the crust. One possible cause is that the rupture mechanism transferred from the thrust faulting in the southwestern portion of the fault to the strike-slip faulting in the northeastern one. The rise time offers an estimate of the dynamic stress drop (37.8±2.3 bars), from which through a macroscopic view the radiated seismic energy of (5.93±0.4) × 10 16 N m is calculated. Although the estimated rupture length (∼210 km) and source duration are shorter than several source rupture models, the current analyses show the rst-order rupture feature of the 2008 Wenchuan earthquake rupturing the Longmenshan fault zone.

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Section: Data and Phase-velocity Measurementsmentioning

confidence: 99%

Section: Data and Phase-velocity Measurementsmentioning

confidence: 99%

Rise time and source duration of the 2008 M W 7.9 Wenchuan (China) earthquake as revealed by Rayleigh waves

et al. 2011

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“…By combining the results of this study, the petrological evidence of Ohara (2006) and the depth constraint between the lithosphere and asthenosphere interface obtained from Chang et al (2007), we set up a 2D density model as shown in Fig. 6 to simulate the gravity anomaly along 15°N.…”

Section: Modeling Of Subsurface Density Structure Along 15°nmentioning

confidence: 99%

“…We assumed the top boundary of the asthenosphere is at depth of 38 km beneath the PVB and 50 km beneath the PKR. These values were inferred from Rayleigh wave dispersions (Chang et al 2007). We also assumed the density of the asthenosphere is 3.25 g cm -3 (Yang et al 1992).…”

Section: Modeling Of Subsurface Density Structure Along 15°nmentioning

confidence: 99%

“…Many geological and geophysical investigations into the PSP have been reported (Seekins and Teng 1977;Seno and Maruyama 1984;Yu and Chang 1991;Oda and Senna 1994;Hall et al 1995;Nakamura and Shibutani 1998;Okino et al 1998Okino et al , 1999Yang and Wang 1998;Fujioka et al 1999;Yu et al 2000;Kamimura et al 2002;Okino and Fujioka 2003;Ohara 2006;Chang et al 2007;Ishihara and Koda 2007;Nishizawa et al 2007Nishizawa et al , 2011Isse et al 2009;Yeh et al 2013). These previous studies suggested that different tectonic/geological structures show distinct velocity structures.…”

Section: Introductionmentioning

confidence: 99%

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The Crustal Thickness of the Philippine Sea Plate Derived from Gravity Data

Yen¹,

Lo²,

Yeh³

et al. 2015

Terr. Atmos. Ocean. Sci.

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We constructed a new free-air gravity anomaly map of the Philippine Sea Plate (PSP) using ship-tracked gravity data from the National Geophysical Data Center (NGDC). Our results show that the isogals trend correlates well with the tectonic structures in the PSP. After removing the gravity induced by sea water from the free-air gravity data, we obtained the regional Bouguer gravity anomaly, which is later used to compute the Moho geometry in the PSP by applying the Parker-Oldenburg iterative method. Our results indicate that in the southern part of the West Philippine Basin (WPB) the crustal thickness is nearly homogeneous with a value of about 5 km, which implies that the WPB is quite stable. The low-amplitude and near-zero free-air gravity anomalies clearly indicate that the whole WPB, except at trenches and island arcs, is nearly in a state of isostatic equilibrium. The average crustal thickness of the Palau Kyushu Ridge (PKR) is more than 10 km. In the eastern PSP the crustal thickness gradually increases eastward. Our results also imply that a relatively thin and low density mantle exists beneath the Parece Vela Basin (PVB) as a consequence of back-arc spreading and serpentinized upwells of the thin crustal thickness.

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Crust and upper mantle structure and its tectonic implications in the South China Sea and adjacent regions

Tang

Zheng

2013

Journal of Asian Earth Sciences

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Lateral Variations of Rayleigh-Wave Dispersions in the Philippine Sea Region

Cited by 9 publications

References 21 publications

Rise time and source duration of the 2008 M W 7.9 Wenchuan (China) earthquake as revealed by Rayleigh waves

Rise time and source duration of the 2008 M W 7.9 Wenchuan (China) earthquake as revealed by Rayleigh waves

The Crustal Thickness of the Philippine Sea Plate Derived from Gravity Data

Crust and upper mantle structure and its tectonic implications in the South China Sea and adjacent regions

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