Abstract:
Although many efforts have been taken in the past years to study the near-fault ground motion observation and its effects on the seismic responses of building structures, the number of near-fault pulse-like ground motion records in mainland China is still very limited. The
Mw6.3 Ludian earthquake in 2014 caused high fatality and severe building damages disproportional to its earthquake magnitude. Despite the insufficient seismic performance of the local buildings and the influence of secondary disasters, the significant near-fault pulse-like ground motion was another important factor. The velocity pulses in the Ludian Earthquake motion records are identified by a quantitative method incorporating wavelet transformation. The characteristics of these pulses are compared with those obtained in the 2008 Wenchuan Earthquake. The comparison shows the velocity pulse in the LLT record has much shorter period but higher peak velocity, which is rare for moderate earthquakes of magnitude about 6. Furthermore, directivity of the pulse energy distribution of the LLT record is observed. Further investigations are needed before attributing the significant velocity pulse to the forward directivity because the LLT station is too close to the epicenter.