Slant-stack velocity analysis for one-dimensional upper mantle structure using short-period data from MAJO

Erdoĝan, Nurcan; Nowack, Robert L.

doi:10.1007/bf00876231

Cited by 7 publications

(13 citation statements)

References 21 publications

(29 reference statements)

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“…The deconvolution process also approximately removes the broadening of pulses caused by attenuation. An example of this type of deconvolution process is given by Erdogan & Nowack (1993). The deconvolved waveforms are then band‐pass filtered from 0.1 to 1.2 Hz.…”

Section: Data and Analysismentioning

confidence: 99%

“…The observation that the northern Philippine Sea anomaly does not extend beyond the northwestern edge of the Philippine Sea plate is supported by two other independent studies. Using short‐period waveform data recorded by the seismic station at Matsushiro, Japan (MAJO), Erdogan & Nowack (1993) constructed a composite seismic profile along the Japan subduction zone. In their regional P ‐wave velocity model, there is no evidence for anomalously fast Vp in the transition zone of the mantle near Japan.…”

Section: Introductionmentioning

confidence: 99%

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A seismic profile of the upper mantle along the southwestern edge of the Philippine Sea plate using short-period array data

Nowack

Chen

et al. 1999

Geophysical Journal International

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We investigated the structure of the P‐wave velocity (Vp) in the upper mantle beneath the southwestern edge of the Philippine Sea plate using traveltimes and waveforms from a dense, short‐period seismic array of approximately 75 seismographs in Taiwan. Using the seismograms from 39 shallow‐focus earthquakes, a composite seismic profile was constructed for a distance range of up to 4000 km. We picked the traveltimes of the first arrivals to construct a smoothly varying model for Vp which also served as a basis for static corrections. After band‐pass filtering and deconvolution to remove effects of source‐time functions and attenuation, we modelled the waveforms and triplicated arrivals in order to constrain the nature of the upper‐mantle discontinuities. Finally, after slant stacking, the entire observed wavefield was downward continued to obtain a regional model TS.406. This model includes a small low‐velocity zone between depths of 105 and 190 km, and then a gradual increase in Vp down to the depth of 406 km. At this discontinuity, Vp increases by 5.5 per cent. The P‐wave velocity then varies linearly in the transition zone with a moderate gradient of 0.0027 km s−1 km−1 until the base of the transition zone at 662 km, where Vp increases by 5.4 per cent. When compared with other models for the Philippine Sea region and average global models, model TS.406 has lower velocities above a depth of 300 km and then faster Vp in the upper part of the transition zone. For example, above 300 km the TS.406 model is slower than IASP91 by 1.5 per cent, but in the upper transition zone (406 to 571 km), it is faster by 1.2 per cent. Thus, the moderate‐amplitude anomaly of fast Vp in the middle of the transition zone reported by tomographic studies seems to occur at shallower depths. Furthermore, unlike the pronounced Northern Philippine Sea anomaly, Vp near the bottom of the transition zone is close to the global average under the southwestern edge of the Philippine Sea.

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Section: Data and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A seismic profile of the upper mantle along the southwestern edge of the Philippine Sea plate using short-period array data

Nowack

Chen

et al. 1999

Geophysical Journal International

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“…While some models in this region have well-established low-velocity zones (Fukao, 1977;Erdögan and Nowack, 1993), model sn12c as well as its mother model 12 of Nakanishi (1989, 1999) does not have a distinct lid; velocity increases smoothly between Moho and the 410-km discontinuity. Strong signature of the low-velocity zone such as shadow zone or discontinuous jump in travel time curve is not seen in our observations.…”

Section: Discussionmentioning

confidence: 99%

“…We first examine several published models for the Kurile-Alaska path (Kanamori, 1967;Fukao, 1977;Erdögan and Nowack, 1993;Nakanishi, 1989 and as well as those for the other part of Pacific (Walck, 1984 and1985;Gaherty et al, 1996), which are tested whether they could explain several possible branches that are . Even for such teleseismic distances, the correlation of the waveforms within the array is low, which indicates that effects of the sites cannot be negligible at MSAS (Kato et al, 2000).…”

Section: Model For the Nej Pathmentioning

confidence: 99%

“…An abrupt change of apparent velocity of direct P phase (e.g., Kishimoto, 1956) and triplicated arrivals in regional distances (e.g., Niazi and Anderson, 1965;Walck, 1984) have been used to construct upper mantle velocity models. Several velocity models have been presented for the western Pacific region, some of which are constructed with measurements of travel times and apparent velocities of P phase (Kanamori, 1967;Fukao, 1977;Inatani and Kurita, 1980;Nakanishi, 1989 and, some are by direct waveform analyses (Erdögan and Nowack, 1993;.…”

Section: Introductionmentioning

confidence: 99%

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Upper mantle velocity structure in the western Pacific rim estimated from short-period recordings at Matsushiro Seismic Array System

Kato

2014

Earth Planet Sp

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We investigate lateral variation of the upper mantle P-wave velocity structure in the western Pacific rim using travel times of P phases from regional shallow events. Onsets of direct and later arrivals are manually picked up from short-period waveforms at Matsushiro Seismic Array System in central Japan by consulting the correlation among the waveforms at seven array stations. For the path along Kurile and Alaska seismic zones, observed first arrivals of shallow events (d = 5-50 km) are well explained by a standard travel time table for Japan. Observations provide no strong evidence of a distinct low-velocity zone in the uppermost mantle, and triplicated branches are adequately explained by a slight modification of model 12 by Nakanishi (1989, 1999). Observed travel times of direct P phases from events along the eastern and western Philippine Sea are slightly larger at around 15• and slightly smaller at around 25• , and the upper mantle is slower and the transition zone and uppermost lower mantle faster in the eastern and western Philippine Sea than in the northwestern Pacific. Such differences could reflect a high temperature in the upper mantle, and accumulation of subducted material at the base of transition zone as a result of the past subduction.

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Applications of Inverse Methods to the Analysis of Refraction and Wide-Angle Seismic Data

Nowack

1997

Inverse Problems in Wave Propagation

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Slant-stack velocity analysis for one-dimensional upper mantle structure using short-period data from MAJO

Cited by 7 publications

References 21 publications

A seismic profile of the upper mantle along the southwestern edge of the Philippine Sea plate using short-period array data

A seismic profile of the upper mantle along the southwestern edge of the Philippine Sea plate using short-period array data

Upper mantle velocity structure in the western Pacific rim estimated from short-period recordings at Matsushiro Seismic Array System

Applications of Inverse Methods to the Analysis of Refraction and Wide-Angle Seismic Data

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