Ambient Noise Measurements following the 2011 Christchurch Earthquake: Relationships with Previous Microzonation Studies, Liquefaction, and Nonlinearity

摘要: Following the Christchurch 2011 earthquake, Basilicata University (Potenza, Italy) organized a field trip to New Zealand mainly examine structural engineering issues but also investigate similarity between this event and L'Aquila 2009 quake that struck central Italy. In both cases an with magnitude slightly above 6 occurred on blind fault underlying area inhabited by population of order hundreds thousands, killing few hundred people severely damaging city center, in site amplification study was available before event. At same time there were striking differences two earthquakes maximum recorded acceleration, nonlinear behavior soils, occurrence liquefaction. It opportunity look at some related use microtremor measurements, particular: 1. verify if soil frequencies estimated more than 15 years ago Toshinawa et al. (1997) are persisting feature or changes following strong motions 2010 2011; 2. usefulness vulnerability index proposed Nakamura (1996) as proxy liquefaction susceptibility; and 3. compare strong-motion recordings elastic limit derived from ambient noise, looking for hints hardening nonlinearity Bonilla (2005) observations (Puglia 2011). In 1994 Arthurs Pass Earthquake ( Ml = 6.6) about 100 km northwest Christchurch. The macroseismic intensity together local amplifications inferred seismic microtremors (Toshinawa 1997). authors found satisfactory correlation among results different techniques prepared microzonation map. As horizontal-to-vertical spectral ratio (HVSR) analysis microtremors, …