Weak-motion-based attenuation relationships for Israel

Abstract

S U M M A R YWe performed a regional study of earthquake ground motion scaling relations to provide the seismic hazard community of Israel with a new attenuation relationship that could be used for the prediction of earthquake-induced ground motion. Strong earthquakes are rather scarce in Israel and the existing collection of records from strong earthquakes is not sufficient to allow the use of traditional regression methods to develop a regional attenuation relationship. We used velocity seismograms from the Israel Seismic Network to estimate the distance and frequency dependence of ground motion in the Israel region from frequent, smaller regional earthquakes. Our analyses included 4814 waveforms recorded by 30 stations of the Israel Seismic Network from 2000 to 2005. We restricted our analysis to 330 events recorded at five or more stations, with duration magnitudes ranging between 1.0 and 5.2. We derived empirical excitation, site and regional attenuation terms by regressing the peak amplitudes of narrowband-filtered seismograms around the shear wave arrivals and the rms Fourier spectral amplitudes taken around the specific sampling frequency. In order to optimize the attenuation parameters in our scaling model, we used a simple grid search. An optimal solution for minimal error between empirical and theoretical attenuation function was found for the quality parameter Q( f ) = 298 f 0.67 and the geometrical spreading g(r ) parametrized as a bilinear, piecewise function: r −0.74 for r ≤ 60 km and r −0.47 for r > 60 km. The spectral parameters κ of 0.015 s and stress drop increasing from 0.3 to 4 MPa were used to model the excitation spectra.A theoretical modelling effort based on Brune's source spectrum and Random Vibration Theory (RVT) was performed on the attenuation and source parameters estimated in this study. Comparison of the attenuation relationship derived with locally measured ground motions shows excellent agreement with the data in the magnitude range for which we have observations and seems to be adequate for predictions of earthquake ground motion for the Israel region. Comparison of Peak Ground Acceleration (PGA) predictions, based on our scaling relationship with those that have been recently used for seismic hazard analysis in Israel shows that our attenuation relationship predicts significantly lower ground motions than other relations.

A 220,000-year-long continuous large earthquake record on a slow-slipping plate boundary

“…In addition, much of the data come from single-site recordings. In the same year, Meirova et al (42) published an alternative PGA-M-D relation but limited to data west of the Dead Sea fault. It predicted much higher magnitudes than the relation of Al-Qaryouti (31) and was not applied to our present study.…”

Attenuation of Ground-Motion Spectral Amplitudes and Its Variations across the Central Alborz Mountains

“…The availability of the abundant weak-motion waveform data from the short-period local seismograph network of the Institute of Geophysics of the University of Tehran (IGUT) provides an opportunity to derive a new and more reliable ground-motion relationship for small events to complement those of strong-motion results. Several recent works have used a similar approach to derive attenuation relationship from weak-motion data (e.g., Allen et al, 2007;Massa et al, 2008;Meirova et al, 2008). We have selected 136 events ranging between M L 2.1 and 6.1.…”

Characterization of earthquake-induced ground motion from the L’Aquila seismic sequence of 2009, Italy

“…Weak-motion studies performed on very large sets of broadband recordings did show significant regional variations in the crustal wave propagation and their anelastic attenuation (Drouet et al 2010). Furthermore, there are several published papers that were carried out in different regions of the world, although nobody ever undertook the effort of a comprehensive comparative study [examples of such regions are: the Apennines, Malagnini et al (2000a; Malagnini & Herrmann (2000), the San Francisco Bay Area, Malagnini et al (2007), the Northeastern Alps, Malagnini et al (2002), the Kachchh Basin, India, Bodin et al (2004), the Erzincan and Marmara regions of Turkey, Akinci et al (2001Akinci et al ( , 2006, the Northwestern Alps, Morasca et al (2006), Eastern Sicily, Scognamiglio et al (2005), Switzerland, Bay et al (2003), Central Europe, Malagnini et al (2000b), Southern California, Raoof et al (1999) and Israel, Meirova et al (2008)].…”