Seismic moment tensor resolution by waveform inversion of a few local noisy records-I. Synthetic tests

SUMMARY Seismic moment tensors are an important tool and input variable for many studies in the geosciences. The theory behind the determination of moment tensors is well established. They are routinely and (semi-) automatically calculated on a global scale. However, on regional and local scales, there are still several difficulties hampering the reliable retrieval of the full seismic moment tensor. In an earlier study, we showed that the waveform inversion for seismic moment tensors can benefit significantly when incorporating rotational ground motion in addition to the commonly used translational ground motion. In this study, we test, what is the best processing strategy with respect to the resolvability of the seismic moment tensor components: inverting three-component data with Green’s functions (GFs) based on a 3-D structural model, six-component data with GFs based on a 1-D model, or unleashing the full force of six-component data and GFs based on a 3-D model? As a reference case, we use the inversion based on three-component data and 1-D structure, which has been the most common practice in waveform inversion for moment tensors so far. Building on the same Bayesian approach as in our previous study, we invert synthetic waveforms for two test cases from the Korean Peninsula: one is the 2013 nuclear test of the Democratic People’s Republic of Korea and the other is an Mw 5.4 tectonic event of 2016 in the Republic of Korea using waveform data recorded on stations in Korea, China and Japan. For the Korean Peninsula, a very detailed 3-D velocity model is available. We show that for the tectonic event both, the 3-D structural model and the rotational ground motion, contribute strongly to the improved resolution of the seismic moment tensor. The higher the frequencies used for inversion, the higher is the influence of rotational ground motions. This is an important effect to consider when inverting waveforms from smaller magnitude events. The explosive source benefits more from the 3-D structural model than from the rotational ground motion. Nevertheless, the rotational ground motion can help to better constraint the isotropic part of the source in the higher frequency range.

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Seismic moment tensor resolution by waveform inversion of a few local noisy records-II. Application to the Phlegraean Fields (Southern Italy) volcanic tremors

Geophysical Journal International ◽

10.1111/j.1365-246x.1996.tb04694.x ◽

1996 ◽

Vol 126 (3) ◽

pp. 620-634 ◽

Cited By ~ 15

Author(s):

G. Cespuglio ◽

P. Campus ◽

J. Ŝílený

Keyword(s):

Seismic Moment ◽

Southern Italy ◽

Moment Tensor ◽

Waveform Inversion ◽

Seismic Moment Tensor ◽

Phlegraean Fields

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Rotational Ground Motion Measurements for Regional Seismic Moment Tensors: a Review

10.31223/x5jg9m ◽

2021 ◽

Author(s):

Stefanie Donner

Keyword(s):

Ground Motion ◽

Seismic Moment ◽

Spatial Scales ◽

Moment Tensor ◽

Waveform Inversion ◽

Seismic Source ◽

Seismic Moment Tensor ◽

Moment Tensors ◽

Rotational Ground Motion ◽

Motion Measurements

Seismic moment tensors are an important tool in geosciences on all spatial scales and for a broad range of applications. The basic underlying theory is established since decades. However, various factors influence the reliability of the inversion result, several of them are mutually dependent. Hence, a reliable retrieval of seismic moment tensors is still hampered in many cases, especially at regional event-receiver distances.To sample the entire wavefield due to a seismic source we need six components: three translational and three rotational ones. Up to now, only translational ground motion recordings were used for moment tensor retrieval, missing out valuable information. Using rotational in addition to the classical translational ground motions during waveform inversion for moment tensors mainly adds information on the vertical displacement gradient to the inversion problem. Furthermore, having available six instead of only three components per receiver location provides additional constraints on the sampling of the radiation pattern. As a result, the moment tensor components are resolved with higher precision and accuracy, even when the number of recording receivers is considerably reduced. Especially, components with a dependence to depth as well as the centroid depth can benefit significantly from additional rotational ground motion. Up to the time of writing this review only a few studies are published on the topic. Here, I summarise their findings and provide an overview over the possible capabilities of including rotational ground motion measurements to waveform inversion for seismic moment tensor retrieval.

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Seismic moment tensor and dynamic parameters of earthquakes in the Central Tien Shan

Geosystems of Transition Zones ◽

10.30730/gtrz.2020.4.2.178-191.192-209 ◽

2020 ◽

Vol 4 (2) ◽

pp. 178-209

Author(s):

N.A. Sycheva ◽

Keyword(s):

Seismic Moment ◽

Moment Tensor ◽

Tien Shan ◽

Seismic Moment Tensor ◽

Dynamic Parameters

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Seismic Moment Tensor Screening on the Hypersphere

10.2172/1499980 ◽

2019 ◽

Author(s):

Sean R. Ford ◽

Gordon D. Kraft

Keyword(s):

Seismic Moment ◽

Moment Tensor ◽

Seismic Moment Tensor

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HybridMT: A MATLAB/Shell Environment Package for Seismic Moment Tensor Inversion and Refinement

Seismological Research Letters ◽

10.1785/0220150251 ◽

2016 ◽

Vol 87 (4) ◽

pp. 964-976 ◽

Cited By ~ 30

Author(s):

Grzegorz Kwiatek ◽

Patricia Martínez‐Garzón ◽

Marco Bohnhoff

Keyword(s):

Seismic Moment ◽

Moment Tensor ◽

Moment Tensor Inversion ◽

Seismic Moment Tensor

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Seismic Moment Tensor Inversion of an Induced Microseismic Event, Offshore Norway: An Insight into the Possible Cause of Wellbore Liner Failure during a Drilling Operation

Seismological Research Letters ◽

10.1785/0220200464 ◽

2021 ◽

Vol 92 (6) ◽

pp. 3460-3470

Author(s):

Zoya Zarifi ◽

Fredrik Hansteen ◽

Florian Schopper

Keyword(s):

Seismic Moment ◽

Moment Tensor ◽

Moment Tensor Inversion ◽

Seismic Moment Tensor ◽

Isotropic Component ◽

High Pump ◽

Dc Component ◽

Pump Pressure ◽

Microseismic Event ◽

Possible Cause

Abstract A microseismic event with Mw∼0.8 was recorded at the Grane oilfield, offshore Norway, in June 2015. This event is believed to be associated with a failure of the wellbore liner in well 25/11-G-8 A. The failure mechanism has been difficult to explain from drilling parameters and operational logs alone. In this study, we analyzed the detected microseismic event to shed light on the possible cause of this event. We inverted for the seismic moment tensor, analyzed the S/P amplitude ratio and radiation pattern of seismic waves, and then correlated the microseismic data with the drilling reports. The inverted seismic moment indicates a shear-tensile (dislocation) event with a strong positive isotropic component (67% of total energy) accompanied by a positive compensated linear vector dipole (CLVD) and a reverse double-couple (DC) component. Drilling logs show a strong correlation between high pump pressure and the occurrence of several microseismic events during the drilling of the well. The strongest microseismic event (Mw∼0.8) occurred during peak pump pressure of 277 bar. The application of high pump pressure was associated with an attempt to release the liner hanger running tool (RT) in the well, which had been obstructed. Improper setting of the liner hanger could have caused the forces from the RT release to be transferred to the liner and might have resulted in ripping and parting of the pipe. The possible direct impact of the ripped liner with the formation or the likely sudden hydraulic pressure exposure to the formation caused by the liner ripping may explain the estimated isotropic component in the moment tensor inversion in the well. This impact can promote slip along the pre-existing fractures (the DC component). The presence of gas in the formation or the funneled fluid to the formation caused by the liner ripping may explain the CLVD component.

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