Quantitative relations of seismic source parameters and a classification of earthquakes

Purcaru, G.; Berckhemer, H.

doi:10.1016/0040-1951(82)90154-8

Cited by 104 publications

(37 citation statements)

References 140 publications

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“…The Pingluo earthquake (M ¼ 8.0, 1739) caused surface rupture of about 85 km (ZHANG et al, 1986). If the width is taken to be 7 km for this ''gap,'' then the ratios of the length to the width of the ruptures were found to be about 34 for the Haiyuan and 12 for the Pingluo earthquakes, which is very close to the value range of 2 -30 given by PURCARU and BERCKHEMER (1982) for the strike-slip type. Haiyuan fault composes a complex boundary zone among the Alashan block, Ordos block and Qinghai-Tibet block (WANG et al, 1990).…”

Section: Discussionmentioning

confidence: 72%

“…It should be pointed out that relation (5) was strongly affected by relations (2) and (3). Since both (2) and (3) are empirical relations that may have sizable fluctuations for different regions, especially for the latter one with the strike-slip case (PURCARU and BERCKHEMER, 1982), the suitability of the relations is the pre-requisite of the result. Support for the general distribution of the seismogenic layer thus defined is provided by comparison of the maximum depth distribution of numerous microearthquakes (Fig.…”

Section: Discussionmentioning

confidence: 99%

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The Thickness of Seismogenic Layer Under the Areas Surrounding the Ordos Block, Northern China

Qin¹

2002

Pure and Applied Geophysics

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A seismic approach was used to calculate the thickness distribution of the seismogenic layer under the block Ordos in northern China. This block was chosen because of its stability, the complicated tectonics around its boundaries and the completeness of the data set. Several strong earthquakes occurred in this area in the 20 th century, with the largest one (Haiyuan, M ¼ 8.4, 1920) in the southwest of the Ordos. Most of the large faults around the Ordos are strike-slip ones. The breaking point (i.e., the saturation of earthquake magnitudes M c ) of the self-similarity from small to large events based on the Gutenberg-Richter relation is calculated. Under the assumption of the L model which expresses that the offset is proportional to the length of the fault (SCHOLZ, 1982(SCHOLZ, , 1990(SCHOLZ, , 1994, the thickness (W c ) of the seismogenic layer is directly related to M c . To display smoothly the change of the thickness of the seismogenic layer and to ensure the reliability of the results, a moving cell of 150 events, with a moving step of 0.1 degree, was adopted. To take advantage of the existing data set, the ''mean value method,'' which is based on the latest complete data information to make the existing data set a 'complete' one, was used to extrapolate it so that the data covers the whole time period. The results show that the average thickness of the seismogenic layer in the southwest, in the northwest and in the east of the Ordos is around 30, 9 and 17 km, respectively. The thickness generally decreases from the southwest to the northeast. This kind of spatial variation is in agreement with the maximum depth distribution of large amounts of microearthquakes, with the correlation coefficient to be about 0.88, and the Moho depth.

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Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

The Thickness of Seismogenic Layer Under the Areas Surrounding the Ordos Block, Northern China

Qin¹

2002

Pure and Applied Geophysics

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“…To simplify the analysis we make the following approximation (3.5) Studies of earthquake rupture processes suggest that observed values of rupture velocity are in this range (e.g., PURCARU and BERCKHEMER, 1982).…”

Section: Expression For Root Mean Square Accelerationmentioning

confidence: 99%

“…Three kinds of distributions are assumed for the crack tip velocity, and the values 200, 300, and 500 are assumed for Q. Each of the assumed distributions of crack tip velocity has an average value in the observed range of earthquake rupture velocity (PURCARU and BERCKHEMER, 1982). HANKS (1980) andMCGUIRE (1981) assumed Q=300 for California earthquakes.…”

Section: Expression For Root Mean Square Accelerationmentioning

confidence: 99%

Peak and root-mean-square accelerations radiated from circular cracks and stress-drop associated with seismic high-frequency radiation.

Yamashita

1983

J,Phys,Earth

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We derive an approximate expression for far-field spectral amplitude of acceleration radiated by circular cracks. The crack tip velocity is assumed to make abrupt changes, which can be the sources of high-frequency radiation, during the propagation of crack tip. This crack model will be usable as a source model for the study of high-frequency radiation.The expression for the spectral amplitude of acceleration is obtained in the following way. In the high-frequency range its expression is derived, with the aid of geometrical theory of diffraction, by extending the two-dimensional results.In the low-frequency range it is derived on the assumption that the source can be regarded as a point. Some plausible assumptionsare made for its behavior in the intermediatefrequency range.Theoretical expressions for the root-mean-square and peak accelerations are derived by use of the spectral amplitude of acceleration obtained in the above way.Theoretically calculated accelerations are compared with observed ones.The observations are shown to be well explained by our source model if suitable stress-drop and crack tip velocity are assumed. Using Brune's model as an earthquake source model, Hanks and McGuire showed that the seismic accelerations are well predicted by a stress-drop which is higher than the statically determined stress-drop. However, their conclusion seems less reliable sinceBrune's source model cannot be applied to the study of high-frequency radiation. According to our results, the seismic accelerations can be explained by a lower stress-drop, even by the same value of static stress-drop, if there are more abrupt changes in the crack tip velocity, the magnitude of its change is larger, or the crack tip velocity averaged over the crack surface is higher. Precise information about crack tip velocity is necessary to estimate the stress-drop associated with high-frequency radiation.It is well known that low-frequency seismic waves provide useful information on earthquake source processes. Low-frequency seismic waves are usually analysed with the aid of a simple dislocation source model. Here, the source parameters, rise time, rupture velocity and final displacement discontinuity, are assumed 225

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“…The earthquake source is represented as a first approximation by a moving dislocation on a fault plane (e.g., HASKELL, 1964;HIRASAWA and STAUDER, 1965;AKI, 1967;KANAMORI and ANDERSON, 1975). Especially, the study of the source process in a long-period domain has been advancing ever since the 1960 Chilean earthquake, and source parameters of recent large earthquakes have been determined very precisely (e.g., PURUCARU and BERCKHERMER, 1982).…”

Section: Introductionmentioning

confidence: 99%

High resolution relative hypocenters of similar earthquakes by cross-spectral analysis method.

Ito

1985

J,Phys,Earth

117

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Temporal seismic observation at Kamikuga (KKG) in Tochigi Prefecture was carried out from December 18, 1982 to February 11, 1983. Four temporal stations have been installed and more than 300 seismic events have been observed. Cross-spectral analysis method (CSAM) are applied for the precise determination of relative hypocenters of microearthquakes.An earthquake swarm, which consists of events with very similar waveforms, was analyzed by CSAM. For some groups of similar earthquakes, it has been demonstrated that relative hypocenters are determined, with an accuracy of about 50 m. We found two kinds of such groups of similar earthquakes.The first kind is characterized by similar earthquakes, occurring in a very short time interval within a very small area. Characteristic separation among the hypocenters of similar events is smaller than a wavelength of P-waves. The second kind is characterized by similar events occurring rather intermittently in a region with a linear dimension much larger than the wavelength. Although the former would correspond to stick-slip similar events studied by many seismologists, the latter will be similar events controlled by frequency characteristics of propagation paths.

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Quantitative relations of seismic source parameters and a classification of earthquakes

Cited by 104 publications

References 140 publications

The Thickness of Seismogenic Layer Under the Areas Surrounding the Ordos Block, Northern China

The Thickness of Seismogenic Layer Under the Areas Surrounding the Ordos Block, Northern China

Peak and root-mean-square accelerations radiated from circular cracks and stress-drop associated with seismic high-frequency radiation.

High resolution relative hypocenters of similar earthquakes by cross-spectral analysis method.

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