### 2.240 García et al. (2005)

• Ground-motion model is:
where Y is in cms2, for horizontal PGA: c1 = -0.2, c2 = 0.59, c3 = -0.0039, c4 = 1, c5 = 0.008, σr = 0.27, σe = 0.10 and for vertical PGA: c1 = -0.4, c2 = 0.60, c3 = -0.0036, c4 = 1, c5 = 0.006, σr = 0.25 and σe = 0.11 where σr is the intra-event standard deviation and σe is the inter-event standard deviation.
• All data from 51 hard (NEHRP B) sites.
• All stations in the Valley of Mexico omitted.
• All data from free-field stations: small shelters, isolated from any building, dam abutment, bridge, or structure with more than one storey.
• Focal depths: 35 H 138km, most records (13 earthquakes, 249 records) from 35 H 75km.
• Exclude data from Mw < 5.0 and R > 400km.
• Exclude data from deep earthquakes where wave paths cross the mantle edge.
• All data from normal-faulting earthquakes.
• Use about 27 records from velocity records from broadband seismograph network that were differentiated to acceleration.
• Adopt Δ from Atkinson and Boore (2003).
• Investigate a number of functional forms. Inclusion of Δ substantially improves fit, leading to a decrease in random variability at close distances, and an increase in c2 and c3 coefficients. Find worse correlation when add a quadratic magnitude term. A magnitude-dependent c4 leads to higher σs. Find unrealistically high ground motions at close distances using the form of c4 used by Atkinson and Boore (2003).
• If exclude three deep earthquakes then little dependence on H.
• Do not find any noticeable bias in residuals w.r.t. distance, magnitude or depth (not shown).
• Note that decrease in variability w.r.t. magnitude is only apparent for frequencies < 1Hz.
• Discuss observed dependence of, particularly high-frequency, ground motions on focal depth.