The first peak ground motion attenuation relationships for North of Vietnam

The first attenuation relationships of peak ground acceleration (PGA) and peak ground velocity (PGV) for northern Vietnam are obtained in this study. Ground motion data are collected by a portable broadband seismic network in northern Vietnam as a part of cooperation between the Institute of Geophysics, Vietnamese Academy of Science and Technology, Vietnam and Institute of Earth Sciences, Academia Sinica, Taiwan. The database comprises a total of 330 amplitude records by 14 broadband stations from 53 shallow earthquakes, which were occurred in and around northern Vietnam in the period between 01/2006 and 12/2009. These earthquakes are of local magnitudes between 1.6 and 4.6, focal depths less than 30 km, and epicentral distances less than 500 km. The new attenuation relationships for PGA and PGV are: log10(PGA)=-0.987+0.7521ML-log10(R)-0.00475R,log10(PGA)=-0.987+0.7521ML-log10(R)-0.00475R,log10(PGV)=-3.244+0.9008ML-log10(R)-0.00322R,log10(PGV)=-3.244+0.9008ML-log10(R)-0.00322R,where PGA is in cm/s2, PGV is in cm/s, and R is the epicentral distance in kilometers. The site corrections are also derived in this study. These site corrections are very suitable with the station corrections for ML and imply the qualification of the resulting attenuation relationships.

► The first PGA attenuation relationship for North of Vietnam log10(PGA)=-0.987+0.7521ML-log10(R)-0.00475Rlog10(PGA)=-0.987+0.7521ML-log10(R)-0.00475R.
► The first PGV attenuation relationship for North of Vietnam log10(PGV)=-3.244+0.9008ML-log10(R)-0.00322Rlog10(PGV)=-3.244+0.9008ML-log10(R)-0.00322R.
► This study provides the site correction values which are suitable with the station correction values of ML scale.