Source Parameters of Weak Crustal Earthquakes of the Vrancea Region from Short-period Waveform Inversion

AbstractThis study comprehensively investigates the source mechanisms associated with the mainshock and aftershocks of the Mw = 6.3 Yogyakarta earthquake which occurred on May 27, 2006. The process involved using moment tensor inversion to determine the fault plane parameters and joint inversion which were further applied to understand the spatial and temporal slip distributions during the earthquake. Moreover, coseismal slip distribution was overlaid with the relocated aftershock distribution to determine the stress field variations around the tectonic area. Meanwhile, the moment tensor inversion made use of near-field data and its Green’s function was calculated using the extended reflectivity method while the joint inversion used near-field and teleseismic body wave data which were computed using the Kikuchi and Kanamori methods. These data were filtered through a trial-and-error method using a bandpass filter with frequency pairs and velocity models from several previous studies. Furthermore, the Akaike Bayesian Information Criterion (ABIC) method was applied to obtain more stable inversion results and different fault types were discovered. Strike–slip and dip-normal were recorded for the mainshock and similar types were recorded for the 8th aftershock while the 9th and 16th June were strike slips. However, the fault slip distribution from the joint inversion showed two asperities. The maximum slip was 0.78 m with the first asperity observed at 10 km south/north of the mainshock hypocenter. The source parameters discovered include total seismic moment M0 = 0.4311E + 19 (Nm) or Mw = 6.4 with a depth of 12 km and a duration of 28 s. The slip distribution overlaid with the aftershock distribution showed the tendency of the aftershock to occur around the asperities zone while a normal oblique focus mechanism was found using the joint inversion.

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Three-dimensional full waveform inversion of short-period teleseismic wavefields based upon the SEM–DSM hybrid method

Geophysical Journal International ◽

10.1093/gji/ggv189 ◽

2015 ◽

Vol 202 (2) ◽

pp. 811-827 ◽

Cited By ~ 36

Author(s):

Vadim Monteiller ◽

Sébastien Chevrot ◽

Dimitri Komatitsch ◽

Yi Wang

Keyword(s):

Hybrid Method ◽

Waveform Inversion ◽

Three Dimensional ◽

Full Waveform Inversion ◽

Full Waveform ◽

Short Period

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Determination of source parameters of small earthquakes from P-wave rise time

Bulletin of the Seismological Society of America ◽

10.1785/bssa0630020599 ◽

1973 ◽

Vol 63 (2) ◽

pp. 599-614 ◽

Cited By ~ 4

Author(s):

M. E. O'Neill ◽

J. H. Healy

Keyword(s):

Rise Time ◽

Source Parameters ◽

P Wave ◽

Simple Method ◽

Zero Crossing ◽

Basic Measurement ◽

Earthquake Source Parameters ◽

Short Period ◽

Stress Drops

abstract A simple method of estimating source dimensions and stress drops of small earthquakes is presented. The basic measurement is the time from the first break to the first zero crossing on short-period seismograms. Graphs relating these measurements to rise time as a function of Q and instrument response permit an estimate of earthquake source parameters without the calculation of spectra. Tests on data from Rangely, Colorado, and Hollister, California, indicate that the method gives reasonable results.

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Source characteristics of earthquakes along the southern San Jacinto and Imperial fault zones (1937 to 1954)

Bulletin of the Seismological Society of America ◽

10.1785/bssa0800051099 ◽

1990 ◽

Vol 80 (5) ◽

pp. 1099-1117 ◽

Cited By ~ 1

Author(s):

Diane I. Doser

Keyword(s):

Heat Flow ◽

Source Parameters ◽

Waveform Inversion ◽

High Heat ◽

Seismogenic Zone ◽

Data Sets ◽

Imperial Valley ◽

Rupture Length ◽

Lower Heat ◽

Inversion Techniques

Abstract Body waveform inversion techniques are used to study the source parameters of four earthquakes occurring between 1937 and 1954 along the southern San Jacinto and Imperial faults (1937 Buck Ridge, 1940 Imperial Valley, 1942 Borrego Mountain, and 1954 Salada Wash events). All earthquakes had simple rupture histories with the exception of the 1940 Imperial Valley main shock, which consisted of at least four subevents whose relative locations indicate unilateral rupture toward the southeast. Earthquakes in regions of high heat flow (>80 mW/m2) had focal depths near the base of the seismogenic zone (8 to 10 km). The 1937 Buck Ridge earthquake, located in a region of lower heat flow, however, appears to have occurred at a shallow (3 ± 2 km) depth. The location, mechanism, and aftershock distribution for the 1942 Borrego Mountain earthquake suggest it could have occurred along the Split Mountain fault, a recently identified northeast-trending cross fault located between the Elsinore and Coyote Creek faults or along an unnamed fault that parallels the trend of the Coyote Creek fault. Moment and rupture length estimates obtained from this study agree well with estimates obtained in previous studies that used different data sets.

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Source parameters and scaling relationships of small earthquakes in the northeastern Caribbean

Bulletin of the Seismological Society of America ◽

10.1785/bssa0710041173 ◽

1981 ◽

Vol 71 (4) ◽

pp. 1173-1190

Author(s):

Arthur Frankel

Keyword(s):

Seismic Moment ◽

Dynamic Stress ◽

Source Parameters ◽

Earthquake Swarm ◽

Fold Increase ◽

Virgin Islands ◽

Scaling Relationships ◽

Short Period ◽

Relative Stress ◽

Stress Drops

abstract The seismic moments and stress drops of 23 earthquakes (1.1 ≦ M ≦ 2.4) that occurred during an earthquake swarm in the Virgin Islands were determined from the analysis of their P waveforms. The data consist of digitally recorded seismograms collected by a short-period seismic network operating in the northeastern Caribbean. The events of the swarm are particularly useful for comparing the relative stress drops of small earthquakes, because their source to receiver paths and focal mechanisms are very similar. The static stress drops calculated for these earthquakes varied from about 0.2 to 2 bars. The data clearly illustrate that the static and dynamic stress drops of these earthquakes generally increased with the size (moment) of the events. The fault radii for these shocks increased with seismic moment, but only by a factor of 2 for a 100-fold increase in seismic moment. The velocity waveforms of the larger events were systematically more impulsive than those of the smaller earthquakes. These observations imply that, for this set of earthquakes, the final fault radius is a function of the stress drop that occurs during the rupture process.

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