Preliminary Study of the 2011 Japan Earhquake (M 9.0) Ground Motion Records

By Flavia De Luca, Eugenio Chioccarelli and Iunio Iervolino.

March 23, 2011. Dipartimento di Ingegneria Strutturale, Università di Napoli Federico II.

The Japan (Tohuku) earthquake that occurred on the 11th of March 2011 was the second one after the 2010 Chile earthquake (M 8.8) of the series of big earthquakes that followed the 2004 Sumatra earthquake (M 9.2) [Zollo A., 2011]. The USGS has updated the magnitude of the Tohoku earthquake in Northern Honshu, Japan, to 9.0 from the previous estimate of 8.9. Independently, Japanese seismologists have also updated their estimate of the earthquake’s magnitude to 9.0. This magnitude places the earthquake as the fourth largest in the world since 1900 and the largest in Japan since modern instrumental recordings began 130 years ago [USGS, 2011]. Records from the main shock of the event have been released few hours later by different networks on the web, herein it is proposed a selection of station recordings that have been employed for the evaluation of peak and cyclic parameters and the elastic acceleration spectra. The selection of the stations was made on the basis of the maximum peak ground acceleration recorded.