Strong Motion Simulation of the M8.0 August 15, 2007, Pisco Earthquake; Effect of a Multi-Frequency Rupture Process
Nelson Pulido*1, Hernando Tavera*2, Zenon Aguilar*3,
Shoichi Nakai*4, and Fumio Yamazaki*4
*1National Research Institute for Earth Science and Disaster Prevention (NIED), 3-1 Tennodai, Tsukuba, Ibaraki 305-0006, Japan
*2Geophysical Institute of Peru (IGP), Calle Badajoz # 169, Mayorazgo IV Etapa, Ate Vitarte, Lima, Peru
*3Faculty of Civil Engineering, National University of Engineering, Av. Túpac Amaru N° 1150, Lima 25, Peru
*4Department of Urban Environment Systems, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
We investigated the broadband frequency (0.05-30 Hz) radiation characteristics of the August 15, 2007, Mw8.0 Pisco, Peru, earthquake by simulating the near-source strong ground motion recordings in Parcona city (PCN) and Lima city (NNA). A source model of this earthquake obtained from long-period teleseismic waveforms and InSar data shows two separate asperities, which is consistent with the observation of two distinct episodes of strong shaking in strong motion recordings. We constructed a source model that reproduces near-source records at low frequency (0.05-0.8 Hz) as well as high frequency (0.8-30 Hz) bands. Our results show that the aforementioned teleseismic source model is appropriate for simulating near-source low frequency ground motion. Our modeling of the PCN record in the broad-frequency band indicates that a very strong high frequency radiation event likely occurred near the hypocenter, which generated a large acceleration peak within the first episode of strong shaking at PCN. Using this “broadband frequency” source model we simulated the strong ground motion at Pisco city and obtained accelerations as large as 700 cm/s2 and velocities as high as 90 cm/s, respectively, which may explain the heavy damage occurring in the city.
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