The 28 February 1969 (Ms 8.0) Cape St. Vincent earthquake is the largest shock to have occurred in the region after the Lisbon earthquake of 1755. However, the study of the rupture process has been limited due to the characteristics of the available seismic data which were analogue records that were generally saturated at both regional and teleseismic distances. Indeed, these data consist of just one accelerograph record at the 25th April Bridge in Lisbon (Portugal) and the observed intensities in the Iberian Peninsula and northern part of Morocco. We have used these data to simulate the distribution of PGV (Peak Ground Velocity) for the 1969 event at regional distances (less than 600 km) by using a 3D velocity model. The PGV values are very important in seismic hazard studies. The velocity model and the methodological approach were tested by comparing synthetic and observed ground velocities at regional distances for two recent, well-studied earthquakes that occurred in this region, namely, the 2007 (Mw = 5.9) and the 2009 (Mw = 5.5) earthquakes. By comparing the synthetic and observed PGA (Peak Ground Acceleration) at Lisbon, the focal depth was estimated equal to 25 km and the seismic moment equal to 6.4 × 10 20 N m (Mw = 7.8) for 1969 earthquake. With these parameters, PGV values were obtained for 159 sites located in the Iberian Peninsula and northern region of Morocco where we have felt intensity values. Using different empirical relations, the instrumental intensity values were calculated and compared with the felt intensities. As a result, the synthetic PGV values obtained in this study for the 1969 earthquake could be used as reference values, and the methodological approach would allow the PGV and intensity to be simulated for other events in the region.

中文翻译：

---

使用合成地面速度研究 1969 年 2 月（Ms 8.0）近海圣文森特角（葡萄牙）地震的 PGV、强运动和强度分布

1969 年 2 月 28 日（Ms 8.0）Cape St. Vincent 地震是 1755 年里斯本地震后该地区发生的最大地震。 然而，由于可用地震数据的特点，对破裂过程的研究受到限制它们是在区域和远震距离上普遍饱和的模拟记录。事实上，这些数据仅包括里斯本（葡萄牙）4 月 25 日大桥的一个加速度计记录以及在伊比利亚半岛和摩洛哥北部观测到的强度。我们已经使用这些数据通过使用 3D 速度模型来模拟 1969 年事件在区域距离（小于 600 公里）处的 PGV（峰值地面速度）分布。PGV 值在地震灾害研究中非常重要。通过比较最近在该地区发生的两次经过充分研究的地震（即 2007 年（Mw = 5.9）和 2009 年（Mw = 5.5）的合成和观测到的区域距离的地面速度，测试了速度模型和方法论方法地震。通过比较里斯本合成和观测到的 PGA（峰值地面加速度），估计 1969 年地震的震源深度等于 25 公里，地震矩等于 6.4 × 10 20 N m (Mw = 7.8)。使用这些参数，我们获得了位于伊比利亚半岛和摩洛哥北部地区的 159 个地点的 PGV 值，我们在这些地点感受到了强度值。使用不同的经验关系，计算仪器强度值并与感觉强度进行比较。因此，