Acceleration Amplitude of the Vertical Component of Colombian Earthquakes

Past studies have demonstrated that the vertical earthquake component can substantially affect the seismic performance of bridges and buildings. This component is typically ignored or, when included in the design, is estimated as two-thirds of the horizontal seismic design earthquake. This paper presents the characterization of the acceleration amplitude of the vertical component of moderate and strong earthquakes in Colombia (Moment magnitude Mw > 4) that occurred between June 1993 and April 2020. A total of 42 seismic records registered at less than 50 km from the rupture plane and with horizontal acceleration peaks greater than 0.05g were selected. The peak ground acceleration (PGA) of the three components and the ratio between those PGAs were calculated. Additionally, the relationship among those parameters and the magnitude and epicentral and hypocentral distances were determined. The results showed that the V/H ratio equal to 2/3 is not always valid to represent the effects of the vertical component in structures subjected to the moderate and strong ground motions in Colombia.