Determination of seismic attenuation structure and source strength by inversion of seismic intensity data: Method and numerical experiment.

Hashida, Toshihiko; Shimazaki, Kunihiko

doi:10.4294/jpe1952.32.299

Cited by 29 publications

(16 citation statements)

References 26 publications

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“…The source acceleration and the dimensionless quality factor (Q) of each block are unknown parameters in the present problem. The frequency band related to the seismic intensity is 0.3-10 Hz (Hashida and Shimazaki 1984). For simplicity in the approach, 1 Hz has been assumed as the reference frequency in the present work.…”

Section: Formulation Of the Problemmentioning

confidence: 99%

“…It has been shown by Hashida and Shimazaki (1984) by numerical experiment that a quantitatively reliable Q structure and the earthquake source strength can be obtained in a region using intensity data. As many seismically active regions have very limited instrumental data, the method proposed by Hashida and Shimazaki (1984) has an advantage of obtaining reliable Q structure for regions where scarcity of digital data create obstacle for such seismological studies. Besides using attenuation structure in the seismological studies, this can be used for the purpose of seismic zonation.…”

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confidence: 98%

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Inversion of seismic intensity data for the determination of three-dimensional attenuation structures in the central gap region of Himalayas

Joshi

2007

Nat Hazards

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The central gap region of Himalaya, which lies in the northern part of the Indian subcontinent, is exposed to great seismic hazard. A three-dimensional attenuation structure (Q) of this region is obtained using the intensity data of four earthquakes (M 4.3-7.0) in the central Himalayan gap region and the damped least square inversion scheme. The technique is based on that given by Hashida and Shimazaki (J Phys Earth 32:299-316, 1984). The obtained Q structure explains the spatial distribution of isoseismals of the stronger earthquakes, which occurred in the recent past. The study area covers the Tehri town, which is the locale of one of the biggest earth fill dams of height 260 m. The spatial distribution of Q suggests that the Tehri town area is surrounded by lower Q medium, and hence any large earthquake in Tehri will pose great seismic hazard.

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Section: Formulation Of the Problemmentioning

confidence: 99%

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confidence: 98%

Inversion of seismic intensity data for the determination of three-dimensional attenuation structures in the central gap region of Himalayas

Joshi

2007

Nat Hazards

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“…In a preceding paper (HASHIDA and SHIMAZAKI, 1984; hereafter referred to as Paper I), we developed a method to estimate the seismic attenuation structure and earthquake source strength by inversion of seismic intensity data. This paper is the first one in which the method is applied to real intensity data.…”

Section: Introductionmentioning

confidence: 99%

Determination of seismic attenuation structure and source strength by inversion of seismic intensity data: Tohoku district, northeastern Japan arc.

Hashida

Shimazaki

1987

J,Phys,Earth

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As the first application of the method of Hashida and Shimazaki (J. Phys. Earth, 32, 299-316, 1984), a three-dimensional seismic attenuation structure and source strengths are estimated by inversion of seismic intensity data for earthquakes that occurred in the Tohoku district, Japan. We carefully selected 1,630 intensity data from 101 earthquakes so that the intensities are consistent with accelerations converted from Kawasumi's relation and so that a well-resolved attenuation structure is obtained. A reasonable fit of the formula proposed in our preceding paper to the actual intensity data guarantees that a systematically biased attenuation structure is not obtained. A comparison of the obtained attenuation structure with velocity structures estimated by previous studies shows that high (low) Q nearly corresponds to high (low) V. The correlation of both structures indicates that the attenuation structure estimated by the proposed method is reliable. The resultant attenuation structure shows a remarkable contrast in the attenuation coefficient and two prominent features. The first feature is low-Q zones down to a depth of 90 km, which corresponds to the distribution of volcanoes. The second is high-Q zones that correspond to the subducting Pacific slab. The high-Q slab is in contact with the high-Q zone in a depth range of 30-60 km, which lies on the east side of the volcanic front. The presence of high-stress earthquakes in this depth range, such as the 1978 Miyagi-ken-oki earthquake, is explained by a model in which the contact of the underthrusting Pacific plate with the surface high-Q zone accumulates higher stress and thus causes stronger seismic coupling. The estimated source strength, which is expressed as a point source acceleration, correlates well with earthquake magnitude. Normalized source acceleration, which is an average acceleration over a source area, is estimated. The acceleration suggests that the stress drop of an earthquake becomes higher with magnitude and with depth. The relation between JMA magnitude (MJ) and seismic intensity at a hypocentral * Now at Seismological and Volcanological Department , Japan Meteorological Agency, Tokyo, Japan. T. HASHIDA and K. SHIMAZAKI distance of 100 km (I100) is found to be I100=1.5 MJ-6.5 for crustal events. This I100 is in agreement with the value reported by Utsu (Bull. Earthq. Res. Inst., 59, 219-233, 1984) which was determined from events excluding those which show anomalous distributions of intensity data. This agreement suggests that our method of estimating earthquake magnitude from intensity data is effective for removing the effect of structure.

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“…Method 2.1 Formulation of predicting seismic intensity We briefly summarize a formulation of HASHIDA and SHIMAZAKI (1984) because it will be used for prediction of intensities. The relation given by KAWASUMI (1943) between JMA seismic intensity scale, integer 1 and the medium value of corresponding acceleration a is emtloved as follows.…”

Section: Introductionmentioning

confidence: 99%

“…Another is to predict a number of felt earthquakes at each JMA station based on the JMA earthquake catalogue. We use a formulation proposed by HASHIDA and SHIMAZAKI (1984) to calculate the seismic intensity and the 3-D attenuation structure together with an empirical relation between 'earthquake size' related to intensity and M_J, obtained by HASHIDA and SHIMAZAKI (1987).…”

Section: Introductionmentioning

confidence: 99%

Predicting JMA seismic intensities based on 3-D attenuation structure and surface amplifying factor: The Tohoku district, Japan.

Hashida

Shimazaki

1987

J,Phys,Earth

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Predictions of seismic intensities are attempted based on a three-dimensional attenuation structure and amplifying factors at stations obtained in the previous study for the Tohoku district, Japan. An empirical relation between `earthquake size' related to the intensity and JMA magnitude M_J is also used. The first prediction is to map spatial distribution of the minimum magnitude M_J of an earthquake which causes intensity 5 at a specific JMA station. The result shows that the effects of regional variation of attenuation and local site condition at the station are important in assessing the seismic hazard. Another attempt is made to predict an annual number of felt earthquakes at each JMA station based on the JMA earthquake catalogue for a period from 1963 to 1984. A comparison of predicted number with the observed one shows a good coincidence between them for each year. This may suggest that the proposed method can successfully predict intensities. However, a comparison of the predicted cumulative number for each intensity grade with the observed one shows that the cumulative numbers for intensities 2, 3, and 4 are underestimated by the proposed method. This result may suggest a nonlinearity between the JMA intensity scale and the logarithm of acceleration, which has been suggested by other evidences.

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Determination of seismic attenuation structure and source strength by inversion of seismic intensity data: Method and numerical experiment.

Cited by 29 publications

References 26 publications

Inversion of seismic intensity data for the determination of three-dimensional attenuation structures in the central gap region of Himalayas

Inversion of seismic intensity data for the determination of three-dimensional attenuation structures in the central gap region of Himalayas

Determination of seismic attenuation structure and source strength by inversion of seismic intensity data: Tohoku district, northeastern Japan arc.

Predicting JMA seismic intensities based on 3-D attenuation structure and surface amplifying factor: The Tohoku district, Japan.

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