Strong Ground Motion and Source Parameters for Earthquakes in the Apennines, Italy

1992 ◽  
Vol 8 (4) ◽  
pp. 529-554 ◽  
Author(s):  
Paolo Capuano ◽  
Paolo Gasparini ◽  
Marcello Peronaci ◽  
Roberto Scarpa
Keyword(s):  
Scaling Laws ◽  
Source Parameters ◽  
Strong Motion ◽  
Accelerometer Data ◽  
Motion Data ◽  
Earthquake Source Parameters ◽  
Spectral Models ◽  
Inversion Procedure ◽  
Decay Parameters ◽  
Stress Drops

Strong motion data from significant earthquakes recorded in the Apennines, Italy, over the period 1975-1985 are analyzed in this paper. We have developed an inversion procedure for studying accelerometer data in the frequency domain and for estimating some basic earthquake source parameters. Spectral models, characterized by a single or two corner frequencies have been tested by utilizing variable high frequency decay parameters to simulate a variety of attenuation and rupture models. A best fit of available data was obtained for mid-crustal Q values around 100-250, decay parameter γ in the range 2-3 and a model consisting of two corner frequencies. This last result is explained in part by the source complexity and in part by a spectral shape contaminated by resonance peaks. The data analyzed are confined to the seismic moment range 1015 - 1019 Nm, with stress drops 100-200 bars (1 bar = 0.1M Pa). We have compared results with scaling laws of source parameters for regions having different tectonic regimes or displaying seismic patterns such as swarms. A trend towards an asymptotic value for regions with extensional tectonics of stress drops around 200 bars is observed.

USGS Near‐Real‐Time Products—and Their Use—for the 2018 Anchorage Earthquake

2019 ◽  
Vol 91 (1) ◽  
pp. 94-113 ◽  
Author(s):  
Eric M. Thompson ◽  
Sara K. McBride ◽  
Gavin P. Hayes ◽  
Kate E. Allstadt ◽  
Lisa A. Wald ◽  
...  
Keyword(s):  
Media Coverage ◽  
Fault Plane ◽  
Source Parameters ◽  
Strong Motion ◽  
Source Characterization ◽  
Motion Data ◽  
Additional Information ◽  
Multiple Products ◽  
Earthquake Source Parameters ◽  
The Media

Abstract In the minutes to hours after a major earthquake, such as the recent 2018 Mw 7.1 Anchorage event, the U.S. Geological Survey (USGS) produces a suite of interconnected earthquake products that provides diverse information ranging from basic earthquake source parameters to loss estimates. The 2018 Anchorage earthquake is the first major domestic earthquake to occur since several new USGS products have been developed, thus providing an opportunity to discuss the newly expanded USGS earthquake product suite, its timeliness, performance, and reception. Overall, the products were relatively timely, accurate, well received, and widely used, including by the media, who used information and visualizations from many products to frame their early reporting. One downside of the codependence of multiple products is that reasonable updates to upstream products (e.g., magnitude and source characterization) can result in significant changes to downstream products; this was the case for the Anchorage earthquake. However, the coverage of strong‐motion stations and felt reports was so dense that the ShakeMap and downstream products were relatively insensitive to changes in magnitude or fault‐plane orientation once the ground‐motion data were available. Shaking and loss indicators initially fluctuated in the first hour or two after the earthquake, but they stabilized quickly. To understand how the products are being used and how effectively they are being communicated, we analyze the media coverage of USGS earthquake products. Most references to USGS products occurred within the first 48 hr after the event. The lack of coverage after 48 hr could indicate that longer‐term products addressing what actions the USGS is taking or what early reconnaissance has revealed might be useful for those people wanting additional information about the earthquake.

scholarly journals Rupture process of the 1987 Superstition Hills earthquake from the inversion of strong-motion data

1990 ◽  
Vol 80 (5) ◽  
pp. 1079-1098 ◽  
Author(s):  
David J. Wald ◽  
Donald V. Helmberger ◽  
Stephen H. Hartzell
Keyword(s):  
Small Area ◽  
Strong Motion ◽  
Rupture Process ◽  
Imperial Valley ◽  
Strong Motion Records ◽  
Motion Data ◽  
Single Asperity ◽  
The Third ◽  
Rupture Model ◽  
Stress Drops

Abstract A pair of significant earthquakes occurred on conjugate faults in the western Imperial Valley involving the through-going Superstition Hills fault and the Elmore Ranch cross fault. The first event was located on the Elmore Ranch fault, Ms = 6.2, and the larger event on the Superstition Hills fault, Ms = 6.6. The latter event is seen as a doublet teleseismically with the amplitudes in the ratio of 1:2 and delayed by about 8 sec. This 8-sec delay is also seen in about a dozen strong-motion records. These strong-motion records are used in a constrained least-squares inversion scheme to determine the distribution of slip on a 2-D fault. Upon closer examination, the first of the doublets was found to be itself complex requiring two episodes of slip. Thus, the rupture model was allowed to have three separate subevents, treated as separate ruptures, with independent locations and start times. The best fits were obtained when all three events initiated at the northwestern end of the fault near the intersection of the cross-fault. Their respective delays are 2.1 and 8.6 sec relative to the first subevent, and their moments are 0.4, 0.9, and 3.5 × 1025 dyne-cm, which is about half of that seen teleseismically. This slip distribution suggests multi-rupturing of a single asperity with stress drops of 60, 200, and 15 bars, respectively. The first two subevents were confined to a small area around the epicenter while the third propagated 18 km southwestward, compatible with the teleseismic and afterslip observations.

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

1973 ◽  
Vol 63 (2) ◽  
pp. 599-614 ◽  
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.

Waveform modeling of the November 1987 Superstition Hills earthquakes

1989 ◽  
Vol 79 (2) ◽  
pp. 500-514 ◽  
Author(s):  
Allison L. Bent ◽  
Donald V. Helmberger ◽  
Richard J. Stead ◽  
Phyllis Ho-Liu
Keyword(s):  
Body Wave ◽  
Source Parameters ◽  
Strong Motion ◽  
Source Depth ◽  
Strong Motion Data ◽  
Waveform Modeling ◽  
Motion Data ◽  
Teleseismic Data ◽  
Slip Event ◽  
Double Event

Abstract Long-period body-wave data recorded at teleseismic distances and strong-motion data at Pasadena for the Superstition Hills earthquakes of 24 November 1987 are modeled to obtain the source parameters. We will refer to the event that occurred at 0153 UT as EQ1 and the event at 1316 UT as EQ2. At all distances the first earthquake appears to be a simple left-lateral strike-slip event on a fault striking NE. It is a relatively deep event with a source depth of 10 km. It has a teleseismic moment of 2.7 ×1025 dyne cm. The second and more complex event was modeled in two ways: by using EQ1 as the Green's function and by using a more traditional forward modeling technique to create synthetic seismograms. The first method indicated that EQ2 was a double event with both subevents similar, but not identical to EQ1 and separated by about 7.5 sec. From the synthetic seismogram study we obtained a strike of 305° for the first subevent and 320° for the second. Both have dips of 80° and rakes of 175°. The first subevent has a moment of 3.6 ×1025 which is half that of the second. We obtain depths of at least 6 km. The teleseismic data indicate a preferred subevent separation of 30 km with the second almost due south of the first, but the error bounds are substantial. This would suggest that the subevents occurred on conjugate faults. The strong-motion data at PAS, however, imply a much smaller source separation, with the sources probably produced by asperities.

scholarly journals Application for source parameters calculations as input for static stress changes studies

2007 ◽  
Vol 40 (4) ◽  
pp. 2008
Author(s):  
P. M. Paradisopoulou ◽  
E. E. Papadimitriou ◽  
V. G. Karakostas ◽  
A. Kilias
Keyword(s):  
Scaling Laws ◽  
Source Parameters ◽  
Active Faults ◽  
Static Stress ◽  
Coulomb Stress ◽  
Coseismic Slip ◽  
Earthquake Source Parameters ◽  
Fault Parameters ◽  
Stress Changes ◽  
Stress Application

The study of static Coulomb Stress changes requires initially the collection of information on the major active faults in a study area concerning their geometry and kinematic properties and then a series of complex calculation for stress changes that are associated with both coseismic displacements of the stronger events and the tectonic loading on these major faults. The Coulomb Stress Application has been developed as a tool to provide a user-friendly way of entering the necessary data and an efficient way to perform the complex calculations procedure. More specifically the aim of the application is a) the collection of data (catalogues of earthquakes, fault parameters) in a relational database, b) the calculation of earthquake source parameters such as the length and the width of the causative fault, and the coseismic slip by using available scaling laws, and finally, c) the execution of all the necessary programs and scripts (e.g. dis3dop.exe, GMT package) to get a map of static stress changes for an area. Coulomb Stress application provides a way to store these data for a study area and it is a method to perform a series of calculations by plotting a series of maps and examine the results for a number of cases.

Source parameters and scaling laws of the 1978 Swabian Jura (southwest Germany) aftershocks

1983 ◽  
Vol 73 (5) ◽  
pp. 1321-1343
Author(s):  
Frank Scherbaum ◽  
Dieter Stoll
Keyword(s):  
Scaling Laws ◽  
Source Parameters ◽  
Source Model ◽  
Local Network ◽  
Corner Frequency ◽  
Strong Increase ◽  
Crack Model ◽  
Data Set ◽  
Stress Drops ◽  
Southwest Germany

Abstract The 3 September 1978, Swabian Jura (southwest Germany) earthquake (MWA = 5.7) was followed by a large number of aftershocks which have been recorded with a local network of five portable seismic stations. The seismic moments, fault radii, and the static stress drops have been determined from the SH displacement spectra using the Brune (1970) source model. The data set is consistent with the Gutenberg-Richter energy-magnitude relation. Below a Wood-Anderson magnitude of about 4, the corner frequencies increase only slowly with decreasing magnitudes. No corner frequency higher than 15 Hz has been observed in the magnitude range down to 0.8. Correspondingly, the high-frequency decay slopes show a strong increase when the corner frequencies are approaching the maximum frequency. This prevents the use of slope data for Q determinations. In terms of the Madariaga (1977) crack model, the data show a strong influence of source complexities on the smaller events.

A Ground Motion Prediction Model for Deep Earthquakes beneath the Island of Hawaii

2015 ◽  
Vol 31 (3) ◽  
pp. 1763-1788 ◽  
Author(s):  
Ivan G. Wong ◽  
Walter J. Silva ◽  
Robert Darragh ◽  
Nick Gregor ◽  
Mark Dober
Keyword(s):  
Prediction Model ◽  
Ground Motion ◽  
Strong Motion ◽  
Nonlinear Least Squares ◽  
Source Model ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Motion Data ◽  
Ground Motion Model ◽  
Stress Drops

Until recently, no ground motion prediction model was available for deep ( >20 km) Hawaiian earthquakes, including the 2006 M6.7 Kiholo Bay earthquake. We developed such a model based on the stochastic point-source model. Strong motion data from the 2006 event and 15 other deep Hawaiian earthquakes of M3.3 to M6.2 were inverted using a nonlinear least-squares inversion of Fourier amplitude spectra to estimate stress drops for input into the stochastic modeling and for the few larger events (M ≥ 5.0), to calibrate the ground motion prediction model. The ground motion model is valid for M3.5 to M7.5 over the Joyner-Boore ( RJB) distance range of 20 km to 400 km and are for 5%-damped horizontal spectral acceleration at 27 periods from PGA (0.01 s) to 10.0 s. The shallow site condition assumed for the model is soil and weathered basalt with a mean VS30 of 428 m/s.

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