Engineering Analysis of Ground Motion Records from the 2001 M_w8.4 Southern Peru Earthquake

Abstract

The Mw 8.4 23 June 2001 Southern Peru earthquake generated intense ground motions in a large region encompassing southern Peru and northern Chile. The earthquake was recorded by seven strong motion stations with peak ground accelerations ranging from 0.04 g to 0.34 g for site-to-fault distances ranging from about 70 km to 220 km. At this time, there are no other strong motion records for an earthquake of this magnitude. Hence, the strong motion data set from this earthquake is unique and of particular interest to engineers dealing with seismic design in subduction regions. This paper presents an engineering analysis of the strong motion records. Shear-wave velocity profiles were measured using Spectral Analysis of Surface Waves methods at four stations. Measured shear-wave velocities are high, indicating that all sites classify as stiff soil sites (Site C) according to the International Building Code classification scheme. The strong motion set is characterized by strong high frequency content at large distances from the fault. Site response contributed at least in part to the observed high frequency content in the ground motions. In general, current attenuation relationships for spectral acceleration underpredicted the observed ground motions.

Strong Ground Motion Attributes of the 2010 Mw8.8 Maule, Chile, Earthquake

“…The Maule data are under-predicted by the AB 2003 relation (positive event terms) to a degree that falls within the normal range of inter-earthquake scatter. However, similar underprediction has been noted by Boroschek and Comte (2006) and Rodriguez-Marek et al (2010) based on analysis of the M w 8.4 South of Peru and Northern Chile earthquake. Whether these larger-than-expected ground motions are systematic for the Chilean subduction zone, which is noted by Kanamori (1986) as having strong mechanical coupling between the subducting and overriding plates, is unknown.…”

Implications of the Mw9.0 Tohoku-Oki Earthquake for Ground Motion Scaling with Source, Path, and Site Parameters

“…In Figure 7, we plot ground motion intensity measures (IMs) at several spectral periods versus magnitude. The data are from AB 2003 (database available through an electronic supplement), the 2001 Southern Peru earthquake (Rodriguez-Marek et al 2010), the Maule, Chile, earthquake (Boroschek et al 2012), and Tohoku-oki earthquake. The data plotted have rupture distances between 70 km and 150 km and include all site conditions.…”

“…Distribution of strong motion data for interface subduction zone earthquakes. Data taken from electronic supplement to Atkinson and Boore (2003) for data prior to 2001, Rodriguez-Marek et al (2010) for the 2001 Southern Peru earthquake, Zhao (2011) for the 2003 Tokachi-oki earthquake, and Boroschek et al (2012) for the Maule earthquake.…”

Chile Strong Ground Motion Flatfile

“…The average shear-wave velocity in the top 30 m is compiled from information collected from different publications (Rodriguez-Marek et al 2010, Riddell et al 1992, Kayen et al 2014, Midorikawa et al 2014, Mohlnar et al 2015), and in 17 stations active and passive array surveys are used to invert for shear-wave velocity profiles (see the Data and Resources section).…”