- Ground-motion model is:
where A is in cm∕s2, a = -0.987, b = 0.7521, c = -0.00475, σ = 0.914 (without site correction) and σ = 0.716 (with site correction)

^{40} - Compute site corrections (absolute factors between 0.34 and 5.72) based on mean residuals w.r.t. each station. Relate site terms to variations in soil conditions.
- Records from portable broadband network of 14 different stations (3 STS-2 and 11 Trillium 40 instruments) operated by Institute of Geophysics (Vietnamese Academy of Science and Technology, Vietnam) and Institute of Earth Sciences (Academia Sinica, Taiwan). Data from 01/2006 to 12/2009
- Focal depths between 0.5 and 28km.
- Only use good-quality records, records with r
_{epi}< 500km and events recored by ≥ 3 stations. - Check signal-to-noise ratios for the weakest records and find ratios > 1.5 for frequencies < 15Hz and hence conclude that data are suitable.
- Try using quadratic M term and using r
_{hypo}rather than r_{epi}and find similar coefficients but higher σ, which relate to poor focal depths or PGAs being associated with surface waves. - Do not consider faulting mechanism because no estimates for selected events and major faults in Vietnam are strike-slip.
- Compare predicted and observed (grouped by magnitude) PGAs w.r.t. r
_{epi}for used data and independent data (SSA-1 instruments) from period 04/1997 to 08/1999 (3.2 ≤ M_{w}≤ 4.3) and 19/02/2001 to 05/03/2001 [Dien Bien, M_{w}5.3 and aftershocks (3 ≤ M_{w}≤ 4.8) recorded at Dien Bien and Tuan Giao]. Find good match for both sets.

^{40}These σs are very large. They are probably given in terms of natural logarithms rather than common logarithms, which are used for the
model of the median.