1. Senior Research Engineer, Earthquake Engineering Research Institute, Univ. of Iceland, 800 Selfoss, Iceland; and Director, Rainrace, Nordurbraut 33, 801 Selfoss, Iceland (corresponding author).
2. Professor, School of Engineering and Natural Sciences, Univ. of Iceland, 101 Reykjavik, Iceland; and Professor, Faculty of Engineering Science and Technology, Norwegian Univ. of Science and Technology, 7491 Trondheim, Norway.