Variations of crustal elastic properties during the 2009 L'Aquila earthquake inferred from cross-correlations of ambient seismic noise

• Published in: Geophysical research letters Vol. 38; no. 24
• Main Authors: Zaccarelli, L., Shapiro, N. M., Faenza, L., Soldati, G., Michelini, A.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 28.12.2011; American Geophysical Union; John Wiley & Sons, Inc
• Subjects: cross-correlations; Earth crust; Earth Sciences; Earth, ocean, space; Earthquake damage; Earthquakes; Elastic properties; Exact sciences and technology; Frequency bands; High frequencies; L'Aquila; Noise; Sciences of the Universe; Seismic activity; Seismic engineering; seismic noise; Seismic phenomena; Seismology; Shaking; Southern Europe; Italy; Europe; Earth; damage; cross-correlation; high frequency; noise; velocity; mainshocks; earthquakes; crust; frequency; elastic properties
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2011GL049750

We retrieve seismic velocity variations within the Earth's crust in the region of L'Aquila (central Italy) by analyzing cross‐correlations of more than two years of continuous seismic records. The studied period includes the April 6, 2009, Mw 6.1 L'Aquila earthquake. We observe a decrease of seismic velocities as a result of the earthquake's main shock. After performing the analysis in different frequency bands between 0.1 and 1 Hz, we conclude that the velocity variations are strongest at relatively high frequencies (0.5–1 Hz) suggesting that they are mostly related to the damage in the shallow soft layers resulting from the co‐seismic shaking. Key Points Seismic velocities in the Earth crust are reduced after the L'Aquila earthquake Velocity reduction is caused by co‐seismic shaking of shallow soft layers Noise correlations provide robust information about tiny crustal variations