Relationships between Felt Intensity and Recorded Ground-Motion Parameters for Turkey

In this paper, empirical relationships between modified Mercalli intensity (MMI) and recorded peak ground-motion parameters are developed for Turkey. Strong ground motion data from moderate-to-large earthquakes are employed along with the corresponding MMI information inferred from isoseismal maps and earthquake damage reports. Linear least-squares regression technique is used to derive the following simple relationships between MMI and peak ground acceleration (PGA), peak ground velocity (PGV), and pseudospectral acceleration (PSA): MMI = 0.132 + 3.884 x log (PGA), MMI = 2.673 + 4.340 x log(PGV), MMI = -0.247 + 3.404 x log[PSA(0.3 s)], MMI = -0: 934 + 4.119 x log[PSA(1.0 s)], and MMI = -0.313 + 4.453 x log[PSA(2.0 s)]. Despite weak dependencies of the residuals on magnitude or distance terms, we also developed refined predictive relationships that includeMw and epicentral distance as independent variables. The simple predictive equations are then compared with similar relationships developed with data from other regions in the world. These comparisons confirm that such relationships should be derived from regional datasets because both the ground-motion content and damage types exhibit local properties. Alternatively, refined relationships, which do not show any regional dependencies, can be employed. Finally, an application is presented in terms of a comparison between the estimated (computed) and observed intensity map of the 17 August 1999 Kocaeli (Mw 7.4) earthquake. The estimated maps from both MMI-PGA and MMIPGV relationships are found to be in close agreement with the observed intensity map.