Geomorphology Characterization of Ica Basin and Its Influence on the Dynamic Response of Soils for Urban Seismic Hazards in Ica, Peru

• Published in: International journal of geophysics 2018-01, Vol.2018 (2018), p.1-12
• Main Authors: Arredondo, Luz, Sulla, Wilfredo, Tavera, Hernando, Bernal, Isabel, Oyola, Javier
• Format: Article
• Language: English
• Subjects: Anomalies; Bouguer anomalies; Dynamic response; Earthquakes; Frequency ranges; Geological hazards; Geomorphology; Geophysical exploration; Geophysical methods; Geophysics; Gravimetric analysis; Hazards; Methods; Multichannel; Noise; Seismic hazard; Seismic response; Seismology; Signal processing; Soil; Soil compaction; Soil dynamics; Soils; Spectral analysis; Stratigraphy; Surface waves; Thickness; Urban areas; Vibration; Wavelengths
• ISSN: 1687-885X; 1687-8868
• DOI: 10.1155/2018/9434251

We evaluated the influence of the geomorphology of Peru’s Ica Basin on the dynamic response of soils of the city of Ica. We applied five geophysical methods: spectral ratio (H/V), frequency-wavenumber (F-K), multichannel analysis of surface waves (MASW), multichannel analysis of microtremor (MAM), and Gravimetric Analysis. Our results indicate that the soils respond to two frequency ranges: F0 (0.4–0.8 Hz) and F1 (1.0–3.0 Hz). The F-K, which considers circular arrays, shows two tendencies with a jump between 1.0 and 2.0 Hz. MASW and MAM contribute to frequencies greater than 2.0 Hz. The inversion curve indicates the presence of three layers of 4, 16, and 60 m with velocities of 180, 250, and 400 m/s. The Bouguer anomalies vary between −17.72 and −24.32 mGal and with the spectral analysis we identified two deposits, of 60 m and 150 m of thickness. Likewise, the relationship between the velocities of 400 and 900 m/s, with the frequency = 1.5 Hz, allows us to determine the thickness for the layers of 60 (slightly alluvial to moderately compact) and 150 m (soil-rock interface). These results suggest that the morphology of the Ica Basin plays an important role in the dynamic behavior of the soils to low frequency.