China seismic intensity scale

The China seismic intensity scale (CSIS) is a national standard of the People's Republic of China[1] used to measure seismic intensity. Similar to the EMS-92 on which CSIS drew reference, seismic impacts are classified into 12 degrees of intensity, or liedu (Chinese: 烈度; pinyin: lièdù; lit. 'degrees of violence') in Roman numerals from I for insensible to XII for landscape reshaping.

The scale was initially formalized by the China Earthquake Administration (CEA) in 1980 and is therefore often referred to by its original title as "China Seismic Intensity Scale (1980)". It was later revised, and adopted as national standard (Guobiao) series GB/T 17742-1999 by the National Quality and Technology Supervision Administration (now the General Administration of Quality Supervision, Inspection, and Quarantine of P.R.C., AQSIQ) in 1999.[2] The standard was set for revision not long before the 2008 Sichuan earthquake.[3]

Liedu scale

Unlike the magnitude scales that objectively estimate the released seismic energy, liedu denotes how strongly an earthquake affects a specific place. It is determined by a combination of subjective evaluations (such as human senses and building damage) and objective kinetic measures. Building damage is further specified with a combination of descriptive qualifiers and a numeric evaluation process.

The following is an unofficial translation of the Appendix I of GB/T 17742-1999.

China Seismic Intensity Table[2]
Intensity Sensations of people on the ground Degree of building damage Other seismic phenomena Horizontal motion on the ground
Seismic phenomena Mean damage index Peak acceleration m/s2 Peak velocity m/s
I Insensible
II Sensible by very few still people indoors
III Sensible by a few still people indoors Doors and windows slightly rattle Suspended objects slightly move
IV Sensible by most people indoors and a few people outdoors, a few people wake up from sleep Doors and windows rattle Suspended objects clearly sway; vessels rattle
V Generally sensible by people indoors and sensible by most people outdoors, most people wake up from sleep Doors, windows, roofs, and building frames shake and rattle; dust falls; tiny cracks appear in plaster; some roof tiles fall; very few roof-top chimneys drop bricks Unstable objects rock or flip over 0.31
(0.22–0.44)		 0.03
(0.02–0.04)
VI Most people are unable to stand stably, a few people flee outdoors in fright Damage—cracks appear on walls, roof tiles fall, some roof-top chimneys crack or fall 0–0.10 Cracks appear in river banks and soft soil; saturated sand layers occasionally burst with sand and water; some standalone brick chimneys slightly crack 0.63
(0.45–0.89)		 0.06
(0.05–0.09)
VII The large majority of people flee outdoors in fright, sensible by bicycle riders, sensible by people in moving motor vehicles Slight destruction— local destruction, cracking, may continue to be used with minor repairs or without repair 0.11– 0.30 River banks collapse; saturated sand layers frequently burst with sand and water, and there are more cracks in soft soil; the large majority of standalone brick chimneys are moderately destroyed 1.25
(0.90–1.77)		 0.13
(0.10–0.18)
VIII Most people rock and shake, walking is difficult Moderate destruction— structural destruction, continued usage requires repair 0.31– 0.50 Cracks also appear in hard dry soils; the large majority of standalone brick chimneys are severely destroyed; treetops bend and break; building destruction causes casualties in humans and livestock 2.50
(1.78–3.53)		 0.25
(0.19–0.35)
IX Moving people fall Severe destruction— severe structural destruction, localized collapse, repairs are difficult 0.51– 0.70 Many cracks appear in hard dry soils; cracks and dislocations may appear in bedrock; landslides and collapses are frequent; many standalone brick chimneys collapse 5.00
(3.54–7.07)		 0.50
(0.36– 0.71)
X Bicycle riders will fall, people in an unstable state will fall away from their original positions, there is a sense of being thrown upward The large majority collapse 0.71– 0.90 Landslides and earthquake fractures appear; arch bridges founded on bedrock are destroyed; the large majority of standalone brick chimneys break or collapse from their bases 10.00
(7.08–14.14)		 1.00
(0.72–1.41)
XI Generally collapse 0.91– 1.00 Earthquake fractures extend a long way; many landslides
XII Drastic change in landscape, mountains, and rivers

Notes about qualifiers: "very few" is less than 10%; "few" is 10%–50%; "most" is 50%–70%; "large majority" is 70%–90%; "generally" is above 90%.

Applications

Historic local seismic intensity is an important reference in quakeproofing existing and future buildings. The national standard Code for Seismic Design of Buildings (GB 500011-2001), published in 2001 and partially revised shortly after the 2008 Sichuan earthquake, includes a list of intensities that each building in designated cities is expected to resist.[4]

See also

Notes and references

  1. ↑ Effectively this only applies to mainland China. Hong Kong and Taiwan each use a different intensity scale. See Seismic intensity scales for more details.
  2. 1 2 CHEN Dasheng, SHI Zhenliang, XU Zonghe, GAO Guangyi, NIAN Jiaquan, XIAO Chengye, FENG Yijun (陈达生、时振梁、徐宗和、高光伊、鄢家全、肖承邺、冯义钧) (1999-04-26). "China Seismic Intensity Scale (中国地震烈度表)" (in Chinese). General Administration of Quality Supervision, Inspection, and Quarantine of P.R.C. Archived from the original on 2008-10-29. Retrieved 2008-09-12.{{cite web}}: CS1 maint: multiple names: authors list (link)
  3. ↑ "Revision of "China Seismic Intensity Scale" started (《中国地震烈度表》修订工作启动)" (in Chinese). China Earthquake Administration (中国地震局). 1999-04-26. Retrieved 2008-09-12.
  4. ↑ XU Zhengzhong, WANG Yayong, et al. (徐正忠、王亚勇等) (2001). "Code for seismic design of buildings (GB 500011-2001) (partially revised in 2008), Appendix A ( 《建筑抗震设计规范》（GB 500011－2001） （2008 年局部修订） 附录 A 我国主要城镇抗震设防烈度、设计基本地震加速度和设计地震分组)". Ministry of Housing and Urban-Rural Development of PRC (MOHURD, 中华人民共和国住房和城乡建设部). Retrieved 2008-09-15.{{cite web}}: CS1 maint: multiple names: authors list (link)
  • Spencer, B.F.; Hu, Y. X. (2001). Earthquake Engineering Frontiers in the New Millennium: Proceedings of the China-US Millennium Symposium on Earthquake Engineering, Beijing, 8–11 November 2000. Taylor & Francis. ISBN 978-90-265-1852-2.
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