scholarly journals Shallow seismic source parameter determination using intermediate-period surface wave amplitude spectra

2012 ◽  
Vol 191 (2) ◽  
pp. 601-615 ◽  
Author(s):  
Benjamin D. Fox ◽  
Neil D. Selby ◽  
Ross Heyburn ◽  
John H. Woodhouse
Keyword(s):  
Surface Wave ◽  
Wave Amplitude ◽  
Seismic Source ◽  
Source Parameter ◽  
Parameter Determination ◽  
Intermediate Period ◽  
Shallow Seismic ◽  
Amplitude Spectra

The 4.6 mb,Lg Northeastern Kentucky Earthquake of September 7, 1988

1993 ◽  
Vol 64 (3-4) ◽  
pp. 187-199 ◽  
Author(s):  
R. Street ◽  
K. Taylor ◽  
D. Jones ◽  
J. Harris ◽  
G. Steiner ◽  
...  
Keyword(s):  
Surface Wave ◽  
Seismic Moment ◽  
Wave Amplitude ◽  
Linear Trend ◽  
Source Parameters ◽  
Strike Slip ◽  
Source Depth ◽  
Nodal Plane ◽  
Amplitude Spectra ◽  
Conjugate Fault

Abstract Source parameters for the September 7, 1988 northeastern Kentucky earthquake have been estimated from the analysis of surface-wave amplitude spectra. The source that best fits the observed data had a seismic moment of 2.0 × 1022 dyne-cm, a mechanism with strike = 198° ± 10°, dip = 51° ± 11°, and slip = −178° ± 17°, (T) trend = 160°, plunge = 25°, (P) trend = 55°, plunge = 28°, and source depth of 4 to 7 km. Thirty-two aftershocks were recorded during 2 weeks of monitoring following the mainshock; 23 of the aftershocks were locatable and fall on a roughly NW-SE linear trend. This trend is subparallel with the NW-SE nodal plane of the mainshock. Our analysis shows the 1988 event to be different from the July 27, 1980 mb,Lg = 5.3 earthquake located 11 km to the northwest. First, the 1988 event is considerably shallower (4 to 7 km) than the 1980 event (14 to 22 km). Second, data from the 1988 event suggest the motion is on a conjugate fault and is in contrast with the 1980 event, which had right-lateral strike-slip on a southeast-dipping plane.

Field comparison of shallow seismic sources

Geophysics ◽  
1986 ◽  
Vol 51 (11) ◽  
pp. 2067-2092 ◽  
Author(s):  
R. D. Miller ◽  
S. E. Pullan ◽  
J. S. Waldner ◽  
F. P. Haeni
Keyword(s):  
Water Table ◽  
Seismic Source ◽  
Single Site ◽  
Seismic Sources ◽  
Shallow Seismic ◽  
Site Characteristics ◽  
Amplitude Spectra ◽  
Different Characteristics ◽  
Magnitude Difference ◽  
Selection Of

Choosing a seismic source for a shallow reflection survey can be the most pivotal decision for the engineering geophysicist. The intent of this paper is to present data that will assist in selection of a shallow seismic source best meeting the goals within the constraints of specific projects, particularly in areas where the water table is near the surface. The data were collected (and displayed as seismograms and amplitude spectra) for 15 different shallow seismic sources in October, 1985, at a single site in New Jersey; they show the different characteristics of each source. Considering the almost three orders of magnitude difference in total source energy between the largest and smallest source, we chose a display format that presented the data as objectively as possible, while still allowing direct source‐to‐source comparisons. Two strong reflections at about 100 and 130 ms probably mark the top and bottom of a clay unit 80 m below the surface at this site. Our previous work and that of our colleagues suggests that, given a specific set of site characteristics, any source could dominate the comparison categories addressed here.

Surface-Wave Amplitude Spectra

1972 ◽  
pp. 101-105
Author(s):  
V. I. Frantsuzova ◽  
A. L. Levshin ◽  
G. V. Shkadinskaya
Keyword(s):  
Surface Wave ◽  
Wave Amplitude ◽  
Amplitude Spectra

The Southeastern Illinois Earthquake of 10 June 1987

1989 ◽  
Vol 60 (3) ◽  
pp. 101-110 ◽  
Author(s):  
K. B. Taylor ◽  
R. B. Herrmann ◽  
M. W. Hamburger ◽  
G. L. Pavlis ◽  
A. Johnston ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Surface Wave ◽  
Seismic Moment ◽  
Wave Amplitude ◽  
Main Shock ◽  
Source Parameters ◽  
Focal Depth ◽  
Precambrian Basement ◽  
Amplitude Spectra ◽  
Best Fit

Abstract The June 10 southeastern Illinois earthquake was the 11th largest earthquake felt in the central U.S. during this century. Source parameters of the main shock were estimated from an analysis of surface-wave amplitude spectra. The source that best fit the observed data has focal depth of 10 ± 1 km; mechanism with strike= 40.6°± 5.9°, dip= 76.2° ± 5.6°, slip= 159.7° ± 6.0°; tension and pressure axes of (T) trend= 357°, plunge= 24°, (P) trend= 89°, plunge= 4°; and a seismic moment of 3.1 * 1023 dyne-cm. With the combined efforts of six institutions, a 24-station analog microearthquake network was deployed around the main shock epicenter. One hundred eighty-five aftershocks were recorded in the first week of monitoring, providing 144 hypocenter determinations. A subset of 51 well recorded events was used for joint relocation and calculation of station corrections for the stations within 100 km of the main shock epicenter. Joint hypocenter locations differ only slightly from the original locations. The spatial distribution of well located aftershocks indicates that the rupture was confined to a pencil-like zone within the Precambrian basement, extending from 7 to 11 km depth.

scholarly journals The comparative analysis of 2018 Alaska earthquakes from surface wave records

2020 ◽  
Vol 2 (1) ◽  
pp. 76-84
Author(s):  
Anastasiya Fomochkina ◽  
Boris Bukchin
Keyword(s):  
Surface Wave ◽  
Focal Mechanism ◽  
Seismic Moment ◽  
Optimal Solution ◽  
Seismic Source ◽  
P Wave ◽  
Wave Spectra ◽  
Earthquake Intensity ◽  
Second Moments ◽  
First Arrival

We consider the source of an earthquake in an approximation of instant point shift dislocation. Such a source is given by its depth, the focal mechanism determined by three angles (strike, dip, and slip), and the seismic moment characterizing the earthquake intensity. We determine the source depth and focal mechanism by a systematic exploration of 4D parametric space, and seismic moment - by solving the problem of minimization of the misfit between observed and calculated surface wave spectra for every combination of all other parameters. As is well known, the focal mechanism cannot be uniquely determined from the surface wave’s amplitude spectra only. We used P-wave first arrival polarities to select the optimal solution. Ana-lyzing the surface wave spectra at shorter periods, we describe the source in an approximation of the stress glut second moments. Using these moments we determine integral estimates of the geometry, the duration of the seismic source, and rupture propagation. The results of the application of this technique for two Alaska earthquakes that occurred in 2018 (with Mw7.9 in January and with Mw7.1 in November) are presented. The possibility of the fault plane identification, which based on the obtained estimates of the focal mechanisms and second mo-ments, is analyzed for both events. Bilateral model of the source is constructed.

Generic Source Parameter Determination and Ground-Motion Prediction for Earthquake Early Warning

2020 ◽  
Vol 110 (1) ◽  
pp. 345-356 ◽  
Author(s):  
Itzhak Lior ◽  
Alon Ziv
Keyword(s):  
Real Time ◽  
Ground Motion ◽  
Early Warning ◽  
Stress Drop ◽  
Seismic Moment ◽  
Source Parameter ◽  
Parameter Determination ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Empirical Relations

ABSTRACT Currently available earthquake early warning systems employ region-specific empirical relations for magnitude determination and ground-motion prediction. Consequently, the setting up of such systems requires lengthy calibration and parameter tuning. This situation is most problematic in low seismicity and/or poorly instrumented regions, where the data available for inferring those empirical relations are scarce. To address this issue, a generic approach for real-time magnitude, stress drop, and ground-motion prediction is introduced that is based on the omega-squared model. This approach leads to the following approximate expressions for seismic moment: M0∝RT0.5Drms1.5/Vrms0.5, and stress drop: Δτ∝RT0.5Arms3/Vrms2, in which R is the hypocentral distance; T is the data interval; and Drms, Vrms, and Arms are the displacement, velocity, and acceleration root mean squares, respectively, which may be calculated in the time domain. The potential of these relations for early warning applications is demonstrated using a large composite data set that includes the two 2019 Ridgecrest earthquakes. A quality parameter is introduced that identifies inconsistent earthquake magnitude and stress-drop estimates. Once initial estimates of the seismic moment and stress drop become available, the peak ground velocity and acceleration may be estimated in real time using the generic ground-motion prediction equation of Lior and Ziv (2018). The use of stress drop for ground-motion prediction is shown to be critical for strong ground accelerations. The main advantages of the generic approach with respect to the empirical approach are that it is readily implementable in any seismic region, allows for the easy update of magnitude, stress drop, and shaking intensity with time, and uses source parameter determination and peak ground motion predictions that are subject to the same model assumptions, thus constituting a self-consistent early warning method.

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