Depth variation of seismic moment and recurrence interval in Japan

AbstractIn repeating seismic event sequences within a specialized horizontal area, the moment magnitude is usually scaled with the recurrence interval. In addition to two horizontal dimensions, the vertical dimension plays a certain role in affecting the scaling law. However, whether and how the changing depth influences the scaling law remain enigmatic. Based on a large number of earthquake records with high-resolution epicenter locations in recent decades in Japan, we focus on a comparison between the 3-D seismic moment and seismic interval, which recognize the vertical dimension as the same dimension as the horizontal distances. The results show that (1) the seismic moment scaling law is applicable in the multiparameter 3-D models by visiting the 1.8 million events collected during a period of 15 years; (2) the vertical dimension of depth plays an important role in the Mo–SI relationship as well as in the variance in the 3-D seismic moment–interval magnitudes; and (3) the seismic moment rate, attributable to the plate convergence rate, varies with area and depth in influencing the regional earthquake recurrence frequency.

Download Full-text

Seismic moment rate and earthquake mean recurrence interval in the major tectonic boundaries around Oman

Journal of Geophysics and Engineering ◽

10.1088/1742-2132/9/6/773 ◽

2012 ◽

Vol 9 (6) ◽

pp. 773-783 ◽

Cited By ~ 10

Author(s):

A Deif ◽

I El-Hussain

Keyword(s):

Seismic Moment ◽

Recurrence Interval ◽

Tectonic Boundaries ◽

Seismic Moment Rate

Download Full-text

The slip deficit along the North Anatolian Fault (Turkey) in the Marmara Sea: Insights from paleoseismicity, seismicity and geodetic data

10.5194/egusphere-egu2020-8809 ◽

2020 ◽

Author(s):

Ersen Aksoy ◽

Mustapha Meghraoui ◽

Renaud Toussaint

Keyword(s):

Seismic Moment ◽

North Anatolian Fault ◽

Marmara Sea ◽

Fault Segment ◽

Seismic Slip ◽

The North ◽

Future Earthquake ◽

Spatial Grid ◽

The Moment ◽

Seismic Moment Rate

The North Anatolian Fault experienced large earthquakes with 250 to 400 years recurrence time. In the Marmara Sea region the 1999 (Mw = 7.4) and the 1912 (Mw = 7.4) earthquake ruptures bound the Central Marmara Sea fault segment. Using historical-instrumental catalogue and paleoseismic results (&#8771; 2000-year database), the mapped fault segments, fault kinematic and GPS data, we compute the paleoseismic-seismic moment rate and geodetic moment rate. The geodetic moment rate is obtained by projecting the measured surface displacements to estimate the strain rate, and evaluating the associated elastic stress rate over a regular spatial grid. The paleoseismic-seismic moment rate is obtained by summing the moment tensors over regions of the spatial grid and periods of time. A clear discrepancy appears between the moment rates and implies a significant delay in the seismic slip along the fault. The rich database allows us to identify the size of the seismic gap and related fault segment and estimate the moment rate deficit. Our modeling suggest that the locked Central Marmara Sea fault segment even including a creeping section bears a moment rate deficit &#160;= 6.4*1017 N.m./yr. that corresponds to Mw &#8771; 7.4 for a future earthquake with an average &#8771; 3.25 m coseismic slip. Taking into account the uncertainty in the strain accumulation along the 130-km-long Central fault segment, our estimate of the seismic slip deficit being &#8771; 10 mm/yr implies the size of the future earthquake ranges between Mw = 7.4 and 7.5.

Download Full-text

THE CONTRIBUTION OF EARTHQUAKES TO THE DEFORMATION OF ZAGROS TECTONIC PROVINCE

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-4-w18-993-2019 ◽

2019 ◽

Vol XLII-4/W18 ◽

pp. 993-999

Author(s):

M. A. Sharifi ◽

A. Bahroudi ◽

S. Mafi

Keyword(s):

Strain Rate ◽

Seismic Moment ◽

Deformation Rate ◽

Seismic Energy ◽

Strain Rates ◽

Average Amount ◽

The Moment ◽

Seismic Moment Rate ◽

Different Parts

Abstract. In this study, we investigate the contribution of earthquakes to the deformation of Zagros province and compare the seismicity and the density of earthquakes in different parts of the province. The mathematics used in this research is based on calculations of moment rates. The seismic moment rate is the average amount of seismic energy releases from the tectonic province in each year. The geodetic moment rate is the average amount of energy which is consumed every year to make deformation in Zagros. The ratio of these two moment rates expresses the contribution of earthquakes in making deformation in Zagros province. According to the calculations, this ratio is estimated to be 13.06%. Along with the information obtained from the moment rates, we can also obtain the shear and the dilative strain rates from the strain rate tensors, which show the volumetric changes and the deformation rate in different parts of the Zagros, respectively. The data used in this study include the focal coordinates of the Zagros earthquakes with their magnitude and the velocity vectors of the Zagros geodynamic network, which are used to calculate the seismic and the geodetic moment rates.

Download Full-text

An algorithm for automated tsunami warning in French Polynesia based on mantle magnitudes

Bulletin of the Seismological Society of America ◽

10.1785/bssa0790041177 ◽

1989 ◽

Vol 79 (4) ◽

pp. 1177-1193

Author(s):

Jacques Talandier ◽

Emile A. Okal

Keyword(s):

Rayleigh Wave ◽

Seismic Moment ◽

Rayleigh Waves ◽

French Polynesia ◽

Tsunami Warning ◽

Period Range ◽

Wave Duration ◽

T Wave ◽

The Moment ◽

Historical References

Abstract We have developed a new magnitude scale, Mm, based on the measurement of mantle Rayleigh-wave energy in the 50 to 300 sec period range, and directly related to the seismic moment through Mm = log10M0 − 20. Measurements are taken on the first passage of Rayleigh waves, recorded on-scale on broadband instruments with adequate dynamical range. This allows estimation of the moment of an event within minutes of the arrival of the Rayleigh wave, and with a standard deviation of ±0.2 magnitude units. In turn, the knowledge of the seismic moment allows computation of an estimate of the high-seas amplitude of a range of expectable tsunami heights. The latter, combined with complementary data from T-wave duration and historical references, have been integrated into an automated procedure of tsunami warning by the Centre Polynésien de Prévention des Tsunamis (CPPT), in Papeete, Tahiti.

Download Full-text

Seismic moment catalog of large shallow earthquakes, 1900 to 1989

Bulletin of the Seismological Society of America ◽

10.1785/bssa0820031306 ◽

1992 ◽

Vol 82 (3) ◽

pp. 1306-1349 ◽

Cited By ~ 2

Author(s):

Javier F. Pacheco ◽

Lynn R. Sykes

Keyword(s):

Seismic Moment ◽

Subduction Zones ◽

B Value ◽

Reference List ◽

Transform Faults ◽

Shallow Earthquakes ◽

Seismicity Rates ◽

Chile Earthquake ◽

The Moment ◽

Earthquake Process

Abstract We compile a worldwide catalog of shallow (depth < 70 km) and large (Ms ≥ 7) earthquakes recorded between 1900 and 1989. The catalog is shown to be complete and uniform at the 20-sec surface-wave magnitude Ms ≥ 7.0. We base our catalog on those of Abe (1981, 1984) and Abe and Noguchi (1983a, b) for events with Ms ≥ 7.0. Those catalogs, however, are not homogeneous in seismicity rates for the entire 90-year period. We assume that global rates of seismicity are constant on a time scale of decades and most inhomogeneities arise from changes in instrumentation and/or reporting. We correct the magnitudes to produce a homogeneous catalog. The catalog is accompanied by a reference list for all the events with seismic moment determined at periods longer than 20 sec. Using these seismic moments for great and giant earthquakes and a moment-magnitude relationship for smaller events, we produce a seismic moment catalog for large earthquakes from 1900 to 1989. The catalog is used to study the distribution of moment released worldwide. Although we assumed a constant rate of seismicity on a global basis, the rate of moment release has not been constant for the 90-year period because the latter is dominated by the few largest earthquakes. We find that the seismic moment released at subduction zones during this century constitutes 90% of all the moment released by large, shallow earthquakes on a global basis. The seismic moment released in the largest event that occurred during this century, the 1960 southern Chile earthquake, represents about 30 to 45% of the total moment released from 1900 through 1989. A frequency-size distribution of earthquakes with seismic moment yields an average slope (b value) that changes from 1.04 for magnitudes between 7.0 and 7.5 to b = 1.51 for magnitudes between 7.6 and 8.0. This change in the b value is attributed to different scaling relationships between bounded (large) and unbounded (small) earthquakes. Thus, the earthquake process does have a characteristic length scale that is set by the downdip width over which rupture in earthquakes can occur. That width is typically greater for thrust events at subduction zones than for earthquakes along transform faults and other tectonic environments.

Download Full-text

The relations between the corner frequency, seismic moment and source dynamic parameters derived from the spontaneous rupture of a circular fault

Geophysical Journal International ◽

10.1093/gji/ggab346 ◽

2021 ◽

Vol 228 (1) ◽

pp. 134-146

Author(s):

Jian Wen ◽

Jiankuan Xu ◽

Xiaofei Chen

Keyword(s):

Stress Drop ◽

Seismic Moment ◽

Dynamic Models ◽

Scaling Law ◽

Boundary Integral ◽

Corner Frequency ◽

Dynamic Parameters ◽

Zone Size ◽

Dynamic Rupture ◽

Scaling Relationships

SUMMARY The stress drop is an important dynamic source parameter for understanding the physics of source processes. The estimation of stress drops for moderate and small earthquakes is based on measurements of the corner frequency ${f_c}$, the seismic moment ${M_0}$ and a specific theoretical model of rupture behaviour. To date, several theoretical rupture models have been used. However, different models cause considerable differences in the estimated stress drop, even in an idealized scenario of circular earthquake rupture. Moreover, most of these models are either kinematic or quasi-dynamic models. Compared with previous models, we use the boundary integral equation method to simulate spontaneous dynamic rupture in a homogeneous elastic full space and then investigate the relations between the corner frequency, seismic moment and source dynamic parameters. Spontaneous ruptures include two states: runaway ruptures, in which the rupture does not stop without a barrier, and self-arresting ruptures, in which the rupture can stop itself after nucleation. The scaling relationships between ${f_c}$, ${M_0}$ and the dynamic parameters for runaway ruptures are different from those for self-arresting ruptures. There are obvious boundaries in those scaling relations that distinguish runaway ruptures from self-arresting ruptures. Because the stress drop varies during the rupture and the rupture shape is not circular, Eshelby's analytical solution may be inaccurate for spontaneous dynamic ruptures. For runaway ruptures, the relations between the corner frequency and dynamic parameters coincide with those in the previous kinematic or quasi-dynamic models. For self-arresting ruptures, the scaling relationships are opposite to those for runaway ruptures. Moreover, the relation between ${f_c}$ and ${M_0}$ for a spontaneous dynamic rupture depends on three factors: the dynamic rupture state, the background stress and the nucleation zone size. The scaling between ${f_c}$ and ${M_0}$ is ${f_c} \propto {M_0^{ - n}}$, where n is larger than 0. Earthquakes with the same dimensionless dynamic parameters but different nucleation zone sizes are self-similar and follow a ${f_c} \propto {M_0^{ - 1/3}}$ scaling law. However, if the nucleation zone size does not change, the relation between ${f_c}$ and ${M_0}$ shows a clear departure from self-similarity due to the rupture state or background stress.

Download Full-text

Analysis of strong-motion data of the 1990 Eastern Sicily earthquake

Annals of Geophysics ◽

10.4401/ag-4124 ◽

1995 ◽

Vol 38 (2) ◽

Author(s):

M. Di Bona ◽

M. Cocco ◽

A. Rovelli ◽

R. Berardi ◽

E. Boschi

Keyword(s):

Frequency Band ◽

Stress Drop ◽

Seismic Moment ◽

Ground Motions ◽

Broad Band ◽

Strong Motion ◽

Moment Magnitude ◽

Corner Frequency ◽

Local Magnitude ◽

The Moment

The strong motion accelerograms recorded during the 1990 Eastern Sicily earthquake have been analyzed to investigate source and attenuation parameters. Peak ground motions (peak acceleration, velocity and displacement) overestimate the values predicted by the empirical scaling law proposed for other Italian earthquakes, suggesting that local site response and propagation path effects play an important role in interpreting the observed time histories. The local magnitude, computed from the strong motion accelerograms by synthesizing the Wood-Anderson response, is ML = 5.9, that is sensibly larger than the local magnitude estimated at regional distances from broad-band seismograms (ML = 5.4). The standard omega-square source spectral model seems to be inadequate to describe the observed spectra over the entire frequency band from 0.2 to 20 Hz. The seismic moment estimated from the strong motion accelerogram recorded at the closest rock site (Sortino) is Mo = 0.8 x 1024 dyne.cm, that is roughly 4.5 times lower than the value estimated at regional distances (Mo = 3.7 x 1024 dyne.cm) from broad-band seismograms. The corner frequency estimated from the accelera- tion spectra i.5 J; = 1.3 Hz, that is close to the inverse of the dUl.ation of displacement pulses at the two closest recording sites. This value of corner tì.equency and the two values of seismic moment yield a Brune stress drop larger than 500 bars. However, a corner frequency value off; = 0.6 Hz and the seismic moment resulting from regional data allows the acceleration spectra to be reproduced on the entire available frequency band yielding to a Brune stress drop of 210 bars. The ambiguity on the corner frequency value associated to this earthquake is due to the limited frequency bandwidth available on the strong motion recordil1gs. Assuming the seismic moment estimated at regional distances from broad-band data, the moment magnitude for this earthquake is 5.7. The higher local magnitude (5.9) compared with the moment magnitude (5.7) is due to the weak regional attenuation. Beside this, site amplifications due to surface geology have produced the highest peak ground motions among those observed at the strong motion sites.

Download Full-text

Long-period mechanism of the 8 November 1980 Eureka, California, earthquake

Bulletin of the Seismological Society of America ◽

10.1785/bssa0720020439 ◽

1982 ◽

Vol 72 (2) ◽

pp. 439-456

Author(s):

Thorne Lay ◽

Jeffrey W. Given ◽

Hiroo Kanamori

Keyword(s):

Point Source ◽

Seismic Moment ◽

Moment Tensor ◽

Strike Slip ◽

The Body ◽

Body Waves ◽

Long Period ◽

Amplitude Data ◽

The Moment ◽

Scalar Moment

Abstract The seismic moment and source orientation of the 8 November 1980 Eureka, California, earthquake (Ms = 7.2) are determined using long-period surface and body wave data obtained from the SRO, ASRO, and IDA networks. The favorable azimuthal distribution of the recording stations allows a well-constrained mechanism to be determined by a simultaneous moment tensor inversion of the Love and Rayleigh wave observations. The shallow depth of the event precludes determination of the full moment tensor, but constraining Mzx = Mzy = 0 and using a point source at 16-km depth gives a major double couple for period T = 256 sec with scalar moment M0 = 1.1 · 1027 dyne-cm and a left-lateral vertical strike-slip orientation trending N48.2°E. The choice of fault planes is made on the basis of the aftershock distribution. This solution is insensitive to the depth of the point source for depths less than 33 km. Using the moment tensor solution as a starting model, the Rayleigh and Love wave amplitude data alone are inverted in order to fine-tune the solution. This results in a slightly larger scalar moment of 1.28 · 1027 dyne-cm, but insignificant (<5°) changes in strike and dip. The rake is not well enough resolved to indicate significant variation from the pure strike-slip solution. Additional amplitude inversions of the surface waves at periods ranging from 75 to 512 sec yield a moment estimate of 1.3 ± 0.2 · 1027 dyne-cm, and a similar strike-slip fault orientation. The long-period P and SH waves recorded at SRO and ASRO stations are utilized to determine the seismic moment for 15- to 30-sec periods. A deconvolution algorithm developed by Kikuchi and Kanamori (1982) is used to determine the time function for the first 180 sec of the P and SH signals. The SH data are more stable and indicate a complex bilateral rupture with at least four subevents. The dominant first subevent has a moment of 6.4 · 1026 dyne-cm. Summing the moment of this and the next three subevents, all of which occur in the first 80 sec of rupture, yields a moment of 1.3 · 1027 dyne-cm. Thus, when the multiple source character of the body waves is taken into account, the seismic moment for the Eureka event throughout the period range 15 to 500 sec is 1.3 ± 0.2 · 1027 dyne-cm.

Download Full-text

Postseismic variations in seismic moment and recurrence interval of repeating earthquakes

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2010.08.027 ◽

2010 ◽

Vol 299 (1-2) ◽

pp. 118-125 ◽

Cited By ~ 43

Author(s):

Kate Huihusan Chen ◽

Roland Bürgmann ◽

Robert M. Nadeau ◽

Ting Chen ◽

Nadia Lapusta

Keyword(s):

Seismic Moment ◽

Recurrence Interval ◽

Repeating Earthquakes

Download Full-text

Seismic Moment Tensor Solutions from GeoNet Data to Provide a Moment Magnitude Scale for New Zealand

10.26686/wgtn.16947268.v1 ◽

2021 ◽

Author(s):

◽

Elizabeth de Joux Robertson

Keyword(s):

New Zealand ◽

Seismic Moment ◽

Moment Tensor ◽

Velocity Model ◽

Moment Tensor Inversion ◽

Moment Magnitude ◽

Seismic Moment Tensor ◽

Waveform Data ◽

Moment Tensors ◽

The Moment

The aim of this project is to enable accurate earthquake magnitudes (moment magnitude, MW) to be calculated routinely and in near real-time for New Zealand earthquakes. This would be done by inversion of waveform data to obtain seismic moment tensors. Seismic moment tensors also provide information on fault-type. I use a well-established seismic moment tensor inversion method, the Time-Domain [seismic] Moment Tensor Inversion algorithm (TDMT_INVC) and apply it to GeoNet broadband waveform data to generate moment tensor solutions for New Zealand earthquakes. Some modifications to this software were made. A velocity model can now be automatically used to calculate Green's functions without having a pseudolayer boundary at the source depth. Green's functions can be calculated for multiple depths in a single step, and data are detrended and a suitable data window is selected. The seismic moment tensor solution that has either the maximum variance reduction or the maximum double-couple component is automatically selected for each depth. Seismic moment tensors were calculated for 24 New Zealand earthquakes from 2000 to 2005. The Global CMT project has calculated CMT solutions for 22 of these, and the Global CMT project solutions are compared to the solutions obtained in this project to test the accuracy of the solutions obtained using the TDMT_INVC code. The moment magnitude values are close to the Global CMT values for all earthquakes. The focal mechanisms could only be determined for a few of the earthquakes studied. The value of the moment magnitude appears to be less sensitive to the velocity model and earthquake location (epicentre and depth) than the focal mechanism. Distinguishing legitimate seismic signal from background seismic noise is likely to be the biggest problem in routine inversions.

Download Full-text