The IASPEI Regional Assembly in Asia was organized at Tangshan, China, during August 1-3, 1996. IASPEI, the Asian Seismological Commission, the State Seismological Bureau of China, and the Municipal Government of Tangshan city, China, were the principal sponsors of this assembly. The local organizing committee headed by Prof. Chen Zhangli, Director-General of the State Seismological Bureau of China, made excellent arrangements for this assembly. Foreign delegates numbering over 90 were very warmly received at the airport and very good arrangements for their stay were made at Beijing from where they were taken by luxury buses to Tangshan on 31 July 1996. The arrangements for the stay at the Tangshan hotel and for other administrative and technical aspects of the assembly were satisfactory.
The assembly program included an Opening Ceremony and a Plenary Session in the forenoon of 1 August 1996. This was followed by 9 Technical Sessions and 3 Workshops covering different themes over the period 1-3 August 1996, and a closing Plenary Session on the evening of 3 August 1996. A comprehensive abstract volume consisting of a total of 280 abstracts was brought out. The assembly was attended by a total of 278 delegates, 92 of these from outside China, representing 29 countries and regions. In all 185 oral and 95 poster presentations were made.
The opening ceremony was chaired by Dr. H. K. Gupta, Acting President of the Asian Seismological Commission. Prof. Chan Zhangli, Director- General of State Seismological Bureau, Dr. Zhang He, Mayor of the Municipal Government, Dr. Yang Qian, Vice-Governor of the Hebei province in which Tangshan city is situated, and Prof. C. Froidevaux, President of IASPEI, addressed the gathering.
Dr. H. K. Gupta extended a warm welcome to the participants and gave a brief background of the genesis of this meeting. He gave an overview of the nature of calamity experienced by Tangshan 20 years back and other recent earthquakes like the Latur (India) earthquake of 29 September 1993 and the earthquake at Kobe (Japan) of 17 January 1995. He also mentioned the high seismicity of the Asia and southern Pacific region which experienced 58 of the total of 101 great earthquakes of magnitude 8 and more during the past 100 years. He ended his opening remarks by complimenting IASPEI, the Asian Seismological Commission, the State Seismological Bureau of China, the Municipal Government of Tangshan City, and all others associated in organizing this assembly.
Prof. Chan Zhangli, Chairman of the local organizing committee, extended a warm welcome to the participants and informed the participants about the scientific program of the assembly. Dr. Zhang He and Dr. Yan Qian in their addresses also extended a warm welcome to participants in general and to foreign delegates in particular, and mentioned that this assembly coincided with the 20 years of rebuilding of Tangshan city after the devastating earthquake of the 1976. Their addresses also included some experiences of the State Government and the people of Tangshan city during the said devastating earthquake of 1976 and the rebuilding of the city thereafter. Prof. Froidevaux, President of IASPEI in his welcome address dwelt upon the role of IASPEI and the Asian Seismological Commission in promoting research in the field of seismology and active interaction between scientists from different countries. The opening ceremony was concluded by Dr. H. K. Gupta thanking the dignitaries on the dais for their encouraging opening remarks. He also expressed his appreciation and thanks for the excellent arrangements made by the hosts.
The opening ceremony was followed by a Plenary Session which was chaired by Dr. H.K. Gupta and included invited talks from Prof. B.L.N. Kennett (Australia) Prof. K. Oike (Japan) Prof. Chen Yuntai (China), and Mr. Zhang Yu, Vice Mayor of the Tangshan Municipal Government. Prof. Brian Kennett addressed certain recent developments in improving the understanding of the seismograms, and dealt with a recently developed technique for automatically picking seismic phases. Prof. Oike addressed the problem of long term cyclic variation of seismicity in southwest Japan and identified certain seismicity distribution patterns associated with major earthquakes. Prof. Chen Yuntai examined the complexities of earthquake source processes using broad band digital seismic waveform data of a few recent earthquakes. The snapshots showing the spatial-temporal release of moment were the highlight of his presentation. Mr. Zhang Yu elegantly addressed the issue of balance development and seismic hazard reduction to forward economic development and social progress. He dwelt on the microzonation aspects using geomorphology, tectonics, etc., and informed that the new constructions and planning of Tangshan city has been done accordingly.
Nine Technical Sessions "S1 to S9" and three Workshops "W1 to W3" were held beginning from the afternoon of 1 August 1996 until the afternoon of 3 August 1996. The various sessions were held in parallel in 3 different conference rooms. The details of the topics covered in these sessions, some salient results presented, etc., are as given below:
Conveners: Prof. Chen Yuntai, Prof. K. Oike
Total Presentations 111 (Oral 55; Poster 56)
This Session attracted the maximum number of presentations. The highlights included new algorithms developed for 3-D rupture analysis by Prof. Chen Yuntai and Dr. D. Helmberger, forecast of earthquakes in Kyrghyzia on the basis of a suite of precursors. Dr. Valiya Hamza addressed the problem of significant thermal anomalies associated with earthquakes. Several precursors were identified in hindsight on the occurrence of large earthquakes, particularly the Tangshan earthquake. Prof. Duda stressed the need of quantification of earthquakes. Du Xingxin presented a faster approach for determining the average stress field using genetic algorithms. The paper by Wang Bing-Hong et al., dealt with multifractal behavior of the spatial distribution of earthquakes and brought out the possibility for intermediate term prediction using Dq dimension spectrum. Yin Xiangchu presented a new approach for earthquake prediction based on the load/unload response ratio theory.
Conveners: Dr. Gao Mengtan, Dr. G. Gibson
Total Presentations 34 (Oral 24; Poster 10)
The presentations and discussion expressed an obvious need to shift from deterministic approach to probabilistic approach of earthquake hazard assessment. According to a paper by Yuxian Hu and Zenping, the probability of Tangshan being hit by an earthquake similar to the 1976, even over the next 100 years, is estimated to be about 10%. Several geotechnical parameters were examined to understand the role played by soil conditions and fault movement in causing damage by past earthquakes. Prof. Bruce Bolt pointed out that displacement is a more important parameter compared to acceleration for estimating the damage potential of a structure. Zhao Fengxin presented a semi-empirical method using the records of small events in the region around an engineering site for generating design accelerograms and response spectra.
Conveners: Prof. Zhang Xiankang, Prof. B.L.N. Kennett
Total Presentations 29 (Oral 23; Poster 6)
In session 3 results were presented from several parts of Asia and Australia. The study by Sun Ruomei and Liu Futiaan indicated that the locale of the Tangshan earthquake is found to be associated with sharp lateral and radial velocity gradients. Prof. Claude Froidevaux presented interesting results on detecting mantle plumes using long-period scattered seismic body waves. Dr. Soren Gregerson offered a physical explanation of Lg waves. A paper by Zhang Xiankang et al., described the results of 3D velocity modeling in parts of north China, including the distribution of deep faults and their satisfactory comparison with deep seismic sounding data. Study of the 660 km discontinuity beneath northeast part of China was the subject matter of a paper by Shao-Xian Zang, et al.
Conveners: Prof. Wan Jiyang, Dr. R. Punongbayan
Total Presentations 15 (Oral 8; Poster 7)
Dr. R.U.M. Rao reported that there is not much variation in the thermal picture over the entire Deccan Volcanic Province of India based on careful measurements in deep boreholes. Dr. Zhang Hunan presented the basic characteristics of Cenozoic Volcanism in coastal area of South China. A paper by Guo Lucan, et al., described the eruption risk of Changbai mountain volcanoes. Other papers addressed problems of dormant volcanoes, crustal structure, heat flow, and seismicity.
Co-Conveners: Prof. Zhu Yuanqing, Prof. M. Ohtake
Total Presentations 11 (Oral 7; Poster 4)
In Session 5, reports on the 1995 Hanshin earthquake by Han Zhujun, et al., and the 1996 Lijiang earthquake by Zyjin Liu and Youjing Su. The presentation by Han Zhujun illustrated that the Hanshin M7.2 earthquake was caused by pivotal movement along a strike-slip fault. Some aspects of the 1993 Latur (India) earthquake and the 1992 Suusamyr earthquake were also presented.
Conveners: Prof. Zang Shaoxian, Dr. U. Raval
Total Presentations 8 (Oral 6; Poster 2)
In Session 6 the papers presented included seismic tomography of subduction zones by B.L.N. Kennett and a conceptual model for intraslab earthquakes by S. Kirby and E.R. Engdahl. Other papers dealt with topics like arc volcanism, topside slab metamorphism, etc.
Conveners: Prof. Gu Guohua, Dr. Phan Trong Trinh
Total Presentations 30; (Oral 15; Poster 15)
Most of the papers in session 7 examined tectonic features, crustal deformation, and their relation to earthquake occurrence.
Conveners: Prof. Yuan Yifan , Dr. Sinan Gencoglu
Total Presentations 8 (Oral 3; Poster 5)
In Session 8 useful topics of medical services, utility lifelines, and ways and means of reducing disaster due to earthquakes were discussed.
Convener: Dr. K. Rajendran
Total Presentations 21 (Oral 10; Poster 11)
In Session 9 the majority of the papers concerned Koyna reservoir in Western India which continues to be the most important site of induced earthquakes in the world and where induced earthquakes have been occurring for the past 34 years. Dr. Kumpel presented results of in situ-pore-pressure measurements in Koyna while Dr. Rastogi underlined the enhanced seismicity in Koyna during 1993-95. Dr. Rajendran presented a model for continued RIS at Koyna. Other papers reported induced earthquakes in China, Thailand, and Vietnam. Yang Zhu'en, et al., presented data on the geology and seismology aspect of induced earthquakes in the Dongjiang reservoir located in south China, making the concluding remark that the maximum magnitude of an induced earthquake in this region is about 4.0.
Conveners: Prof. Zhang Peizhen, Mr. S.C. Bhatia
Total Presentations 7 (Oral 7)
In Workshop 1 recent results of GSHAP Test Area #8, comprising eastern Himalaya, Nepal, South China, Bangla Desh and Myanmar, were discussed. Dr. Peizhen Zhang concluded these presentations with his latest results where the test area has been divided into 20 zones and probabilistic estimates of accelerations have been made. Other papers in this Workshop gave earthquake hazard estimates in Bangla Desh and Nepal.
Convener: Prof. Bruce A. Bolt
Total Presentations 2 (Oral 2)
In Workshop 2 Prof. Bruce Bolt underlined the need to set up World Wide Webs on earthquake information. Such services are already functional at the California Earthquake Data Center, the State Seismological Bureau, China, and some locations in Switzerland, Australia, etc. It was emphasized that this facility needs to be created at all seismological study centers. It was suggested that an international working group on this problem be set up.
Conveners: Prof. Chen Yong, Dr. Avi Shapira
Total Presentations 6 (Oral 6)
One of the highlights was a presentation by Dr. E.R. Engdahl showing improvements in teleseismic earthquake locations using improved travel times and procedures for depth determination.
Although at its 1995 General Assembly IASPEI had already granted commission status to the ASC, it remained necessary to complete this process by taking the steps required to formally establish the Asian Seismological Commission. This was accomplished at the first ASC Council meeting, held on 3 August 1996 and chaired by Dr. E.R. Engdahl, Secretary-general of IASPEI, at which statutes for the commission were adopted, officers elected, and a time and venue for the next ASC General Assembly set. Dr. Engdahl noted that IASPEI is pleased to welcome the ASC to its family of regional commissions and to recognize the newly elected officers (President, Dr. Harsh Gupta; Vice Presidents, Drs. Kazuo Hamada and Gary Gibson, and Secretary- General, Prof. Zhu Chuanzhen. IASPEI especially encourages all Asian and Pacific member nations to actively participate in the new commission. It was proposed that a General Assembly of the Asian Seismological Commission and a Symposium on seismology related topics be organized in 1998 at the National Geophysical Research Institute, Hyderabad, India. Dr. H.K. Gupta, Director, NGRI agreed to take the responsibility and to play host.
Also, a visit to the Tangshan Earthquake Museum ruins of 1976 Tangshan earthquake, Pottery and Porcelain Museum etc. were organized in the afternoon of 2 August 1996. A cultural program with a Chinese traditional performance was organized later in the evening.
The closing plenary session was held in the afternoon of 3 August 1996 under the Chairmanship of Prof. Zhu Chuanzhen, Acting Secretary-General of the ASC. Dr. H.K. Gupta, Acting Chairman of ASC addressed the gathering and provided a brief overview of the scientific deliberations during the 3 days meeting. He also expressed his thanks to the conveners and the speakers and remarked that the scientific content of all the papers were of a very high quality. Prof. He Yongina, Deputy Director-General of the State Seismological Bureau of China, Mr. Han Shengyu, Vice Mayor of Tangshan Municipal Government, and Dr. E.R. Engdahl, Secretary General of IASPEI, also addressed the gathering. Dr. Engdahl expressed his appreciation, on behalf of IASPEI, for the successful organization of this assembly.