Point-source inversion techniques

Langston, Charles A.; Barker, Jeffrey S.; Pavlin, Gregory B.

doi:10.1016/0031-9201(82)90110-8

Cited by 37 publications

(21 citation statements)

References 18 publications

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“…However, as a variable mechanism is not a reasonable assumption for weak events, the independent MTRFs must be reduced afterwards by retrieving their correlated part only, which represents the joint STF, and a constant MT. Thus, the scheme implements the indirect parameterization of the point source: instead of determining directly the MT and STF as traditional approaches do (e.g., LANGSTON et al, 1982;MAO et al, 1994), the independent MTRFs are involved. The advantage is that the bulk of the calculation -inversion of waveforms into the MTRFs -is performed in the linear step and thus it is very fast.…”

Section: Theorymentioning

confidence: 99%

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

Ardeleanu

Rădulian

Šı́lený

et al. 2005

Pure appl. geophys.

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High-frequency records of nine low magnitude shallow earthquakes of the Vrancea (Romania) seismic region are inverted for the seismic moment tensor (MT). An approach is suggested regarding how to obtain at least a rough estimate of the MT when the information on the structure of the crust is poor. Here simple 1-D layered models are used in the Green's function synthesis despite the fact that the structure of the region is undoubtedly very complex. Different 1-D models were used for different source-station paths to approximate lateral variations. Record of a station located on a ray path which crosses a structure differing substantially from a 1-D model may however bias the retrieved MT essentially. Therefore, we did not collectively process all records, but subsets of stations separately. We check the consistency of the MTs resulting from these individual ''bootstrap'' solutions, and reject those which differ substantially, assuming that this is due to the oversimplification of the forward modeling. Thereafter, the averaged moment tensor yielded by the consistent subsets is accepted. Moreover, the distribution of the T, N and P axes from the moment tensors used for averaging provides a rough estimate of their reliability.Following this simplistic procedure, we found seven acceptably constrained solutions among nine events processed. Their P axes are compared with the general trend of the stress in the area: three comply with it, the others should be attributed to the complex stress field active in the region.

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Section: Theorymentioning

confidence: 99%

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

Ardeleanu

Rădulian

Šı́lený

et al. 2005

Pure appl. geophys.

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“…We need strength and different tensor components acting in the focal regions of different earthquakes to represent the seismic moment tensors of earthquakes. The strength of force is calculated from the relation of seismic moment and magnitude mentioned earlier and their directions from the known fault plane solutions (LANGSTON et al, 1982;AKI and RICHARDS, 1980). The known focal mechanism solutions are assumed to be the representative of all earthquakes, which lie nearest to them.…”

Section: Discussionmentioning

confidence: 99%

Strain rates and earthquakes in the Himalayan and nearby regions.

Sigh

1987

J,Phys,Earth

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“…This pattern can be observed between the years of 1907 and 1917 and the 1940s, with maximum intensities of I ‫ס‬ VIII (see Table 1 et al, 2005), and invert for the deviatoric moment tensor by minimizing the L2-misfit between observed and predicted time-domain displacement seismograms (Langston et al, 1982). Waveforms are filtered in an intermediate period band (20-50 sec for the mainshock) to obtain appropriate path corrections.…”

Section: Focal Mechanismmentioning

confidence: 99%

An Overview of the Damaging and Low Magnitude Mw 4.8 La Paca Earthquake on 29 January 2005: Context, Seismotectonics, and Seismic Risk Implications for Southeast Spain

Benito

Capote

Murphy³

et al. 2007

Bulletin of the Seismological Society of America

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This article presents an overview of the La Paca earthquake of magnitude m bLg 4.7, which occurred on 29 January 2005, with its epicenter located near the town of Avilés in the Murcia region in southeast Spain. Despite its low magnitude, the earthquake caused important damage in two towns of the epicentral area, La Paca and Zarcilla de Ramos. These areas recorded intensities of VI-VII (European Macroseismic Scale, 1998) and sustained estimated economic losses amounting to 10 million €. Aftershocks continued for more than 2 weeks, producing considerable alarm in the population and mobilizing emergency services from the whole region. The La Paca seismic series is the third registered in the region in the past 8 years, being preceded by the Mula (1999) and southwest Bullas (2002) seismic series. These main events had also low magnitudes (m bLg 4.8) and caused damage levels similar to the 2005 earthquake. The case is an example of a moderate seismic zone where low-magnitude and frequent earthquakes have important implications on the seismic hazard and risk of the region. Although these are not the largest expected earthquakes, they have yielded important information for improving the knowledge of the seismic activity of the area. With this aim in mind, different topics have been analyzed from a multidisciplinary perspective, including seismicity, local tectonics and surface geology, focal mechanisms, macroseismic effects, and ground motion. Results indicate a local tectonic interpretation, consistent with a strike-slip focal mechanism, the confirmation of a triggering process between the 2002 and 2005 earthquakes, a geotechnical and ground-motion characterization for the damaged sites (supporting local amplification effects and estimated peak ground acceleration values of ϳ0.1g), and an understanding of damage patterns in relation to local building trends. The results may be used as guidelines for future revisions of the Spanish Building Code (Norma de la Construcción Sismorresistente Española [NCSE-02], 2002). The study results should contribute to risk mitigation in a region where strong-motion records from the maximum expected earthquakes are not available. This approach can be extended to other regions with similar seismic backgrounds and a lack of strong-motion records.

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Point-source inversion techniques

Cited by 37 publications

References 18 publications

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

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

Strain rates and earthquakes in the Himalayan and nearby regions.

An Overview of the Damaging and Low Magnitude Mw 4.8 La Paca Earthquake on 29 January 2005: Context, Seismotectonics, and Seismic Risk Implications for Southeast Spain

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