THEME Tl: SEISMICITY AND STRONG GROUND MOTION

This theme covered the various aspects of seismic hazard assessment, ranging from instrumentation and data collection to seismic hazard maps and zonation. The subject was subdivided into the following four half-day sessions:

Tl-1: Strong Ground Motion-Data and Instrumentation;

Tl-2: Theoretical Simulation of Ground Motion; Engineering Design Parameters;

Tl-3: Attenuation Relationships;

Tl-4: Seismic Hazard Assessment and Microzoning.

Sixty-three papers in all were retained for these four topics, comprising both oral and poster presentations in each of the sessions. Their internal organisation is described below.

Session T-1. Chairman Dr. J. Carl Stepp, who gave a brief introduction of the theme, opened the session. After this overview, Prof. N. N. Ambraseys on «Strong-motion data acquisition, processing, and dissemination in Europe and the Middle East» delivered an invited lecture. Four oral presentations and a viewing period for the posters followed the lecture. The session closed with a panel discussion with Dr. Patrick Smit as moderator.

Session T-2. The session began with a succinct introduction of the theme by Chairman Dr. Martin Köller, giving an overview of the day's presentations. The session continued with seven selected oral presentations, followed by a viewing period for the poster presentations. A closing panel discussion specifically addressed the contribution of soil dynamics to engineering seismology, with Dr. Hormoz Modaressi acting as moderator.

Session Tl-3. Chairman Dr. Yoshi Fukushima, who briefly introduced the subject-one viewed with growing interest within the scientific community, opened the session. The session continued with six selected oral presentations and a viewing period for the poster presentations. A panel discussion moderated by Prof. N. N. Ambraseys elicited interesting comments from the participants, reflecting changing attitudes in this field. The issue of ground motion calculation in Eurocode 8 was one that gave rise to particularly animated debate. An ad-hoc task group is to be formed within EAEE to harmonise different proposals and suggestions.

Session Tl-4. Chairman Prof. Kyriazis Pitilakis, followed by seven selected oral presentations and a viewing of the poster, made introductory remarks summarising these theme presentations.

Lastly, to close and sum up this theme, a spontaneous discussion session was held, moderated by B. Mohammadioun. It afforded participants and contributors the opportunity to examine together the various aspects of the four subjects composing this theme and which are central to earthquake engineering problems. All present, notably, were asked to reflect upon what parameters they believed influenced the severity of ground motion most strongly and which accordingly constituted a priority for future research. A sheet entitled, "Key Parameters: How Important Are They?" was handed out, which allowed them to rate these factors by order of importance.

Reported by B. Mohammadioun