Deterministic seismic hazard parameters and engineering risk implications for the Hong Kong region A.M. Chandler a, * , L.S. Chan b , N.T.K. Lam c a Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong b Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong c Department of Civil & Environmental Engineering, The University of Melbourne, Parkville, Victoria 3052, Australia Received 6 October 1999; revised 31 August 2000; accepted 23 February 2001 Abstract The paper reviews and compares recent regional studies evaluating the seismic hazard parameters required to assess the seismic risk to engineering construction in the Coastal Region of South China CRSC) including Hong Kong HK). The review establishes that the CRSC, and in particular the offshore seismic belt, has mean earthquake magnitude recurrence intervals MRIs) or return periods that are 2±3 times shorter than those in the eastern United States EUS), with which the HK region has been compared. An ensemble of realistic design-level earthquakeeventssuitableforde®ningtheregionalseismichazardandforundertakingengineeringriskassessmentisthenformulated,inthe form of deterministic magnitude±distance pairs associated with earthquake magnitudes having a range of MRIs, and the signi®cance of the maximumcredibleearthquakeMCE)magnitudeishighlighted.Next,thescenarioearthquakeeventshavebeenusedtopredicttheexpected levels of peak design ground motions for bedrock) in the HK region. The approximate method proposed here indicates that peak effective) ground accelerations may reasonably be estimated to be around 10% g for 500-year earthquake events and 15±20% g for 1000-year events. However, the predicted ground motions arising from design-level earthquake events indicate large uncertainties arising from the attenuation equations. The uncertainties arise from both epistemic event-to-event) and aleatory site-to-site) considerations. These uncertainties represent the greatest source of errors in de®ning the seismic hazard for engineering design purposes. Further research is required to de®ne the attenuation characteristics of ground motions for the CRSC, across a range of parameters including ground displacement and velocity as wellasacceleration.ItisfurtherfoundthattheChineseearthquakebuildingcodegivesareasonablyconservativeestimateofseismicdemand fortheregion,andisquiteconsistentwithresultsfrombothprobabilisticandpseudo-probabilisticseismichazardanalysiscarriedoutherein, andbyotherresearchersoverthepast7years.Finally,adiscussionispresentedofsomekeyissuesrelatedtoearthquake-resistantdesignand performance in Hong Kong, including the necessity to consider a range of design-level events with different MRIs when implementing acceptable structural design for earthquake effects. q 2001 Elsevier Science Ltd. All rights reserved. Keywords: Seismic; Hazard; Deterministic; Engineering; Risk; Ground; Motion 1. Introduction A number of major Chinese cities with strategic and regional economical signi®cance, including Hong Kong, Macau, Guangzhou provincial capital city of Guangdong) andShantou,arelocatedwithintheCoastalRegionofSouth China CRSC). Over the past 900 years, around one earth- quake exceeding magnitude M  5 has occurred in the region every 20±25 years on average. Earthquake magni- tudes for events occurring prior to 1920 when instrumental records taken by the Hong Kong Observatory commenced) have been interpreted from historical descriptions giving an indication of seismic intensity in the epicentral region Lee et al., 1996). Earthquakes have been considered here from a source area of approximately 400,000 km 2 that straddles across the South China coastline, as shown in Fig. 1. Five events exceeded magnitude M  7 and 11 events exceeded magnitude M  6, amongst the records. The largest events have occurred in the Shantou area, NE of Hong Kong, with four earthquakes having M . 7.An M  6.8 event occurred in the Taiwan Straits in 1994, which was felt throughout the South China region including Hong Kong maximum MM intensity of V±VI). The M  7.6 event that occurred in central Taiwan in September 1999, was also widely felt in Hong Kong, with maximum MM intensity estimated at IV. As a result, the potential threat to lives and properties of the unpreparedcommunityintheregionfrommoderatetolarge earthquakes has been a growing concern in recent years. This paper presents a simpli®ed, pseudo-probabilistic Journal of Asian Earth Sciences 20 2001) 59±72 1367-9120/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved. PII:S1367-912001)00024-4 www.elsevier.com/locate/jseaes * Corresponding author. Tel.: 1852-2859-1973; fax: 1852-2559-5337. E-mail address: amchandl@hkucc.hku.hk A.M. Chandler).