Regional Characteristics Of The Probabilistic Tsunami Hazard For The Southeast Coastal Area Of China

The southeast coastal area of China is the most economically developed area in China.There are many major projects along the coast.Once these areas are attacked by the tsunami,there will be have serious consequences.Recently a number of studies have been done on tsunami mitigation and prevention in China.Probabilistic tsunami hazard analysis method for the southeast coastal area of China has gradually matured.As a result,the South China Sea has been generally recognized as a zone of high risk of tsunami.However,most tsunami hazard assessments have been conducted at the city level.No research has been conducted on tsunami hazard analysis of the entire southeast coastal area.To solve this issue,we do some relevant work as following:(1)Considering the comprehensive impact of both the eight local and regional potential tsunami sources the probabilistic tsunami hazard analysis(PTHA)was adopted for the southeast coastal area of China.The tsunami hazard map was consequently delineated,which shows that the level of tsunami hazard is relatively highest for the Fujian Province,moderate for the Guangdong Province and lowest for the Zhejiang and Hainan Provinces.Four major cities including Hong Kong,Macao,Xiamen and Quanzhou were taken as typical examples to calculate the probability of tsunami wave height exceeding a given height(h?H)and the return periods,and analyze the contribution of each tsunami potential source to the PTHA calculations.The results show that the tsunami hazard is serious at Xiamen and Quanzhou where the return periods of tsunami waves exceeding one meter are 281 years and 589 years respectively;the tsunami hazard is slight at Hong Kong and Macao where the return periods are more than 1000 years.The contribution of Manila potential tsunami source to the PTHA calculation at southeast coastal area of China is greater than each one of eight local sources.The characteristics of tsunami hazard along the southeast coast of China are remarkably regional,dominated by the relative spatial geographical position between the measured site of interest and the potentail tsunami source.(2)Deterministic method is used to analyze the impact of Manila regional potential tsunami source on the southeast coastal area of China under different scenarios.The results show that when the location of the epicenter is located in the first and second segment of Manila regional tsunami source,the tsunami has greater impact on the southeast coastal area of China.When the tsunami triggered by the 9.0 earthquake occurred in the Manila regional potential tsunami source,the tsunami wave height is less than one meter in north of the Taiwan strait and more than two meter in south of the Taiwan strait.In some locations the tsunami wave height exceeded six meters.(3)The sensitivity of the upper limit of the magnitude to the PTHA results was researched.Taking the Manila regional tsunami source as an example,the influence of the uncertainty of the magnitude upper limit of the potential tsunami source is analyzed.The results show that the hazard of Manila regional potential tsunami source increases with the increase of the upper limit of magnitude,moreover the sensitivity of wave height to upper limit of magnitude increases as the return period increases.(4)To improve the existing problems of tsunami wave height distribution fitting for traditional PTHA method,truncated lognormal distribution was used instead of lognormal distribution for wave height fitting,and the results obtained by two methods were compared.The result shows that the PTHA result of using truncated lognormal distribution is less than the way using lognormal distribution.