Международная карта глобальной сейсмической опасности



Карта глобальной сейсмической опасности. 43 Кбайт.

Карта глобальной сейсмической опасности GSH МAP, представленная в пиковых ускорениях колебания грунта, которые с вероятностью 10% могут быть превышены в течение 50 лет, что соответствует периоду повторяемости таких сейсмических воздействий в среднем один раз в 500 лет  (точнее, в 475 лет).

(ниже приведена эта же карта, пересчитанная автором в баллы шкалы сейсмической интенсивности)


The Global Seismic Hazard Assessment Program (GSHAP) was launched in 1992 by the International Lithosphere Program (ILP) with the support of the International Council of Scientific Unions (ICSU), and endorsed as a demonstration program in the framework of the United Nations International Decade for Natural Disaster Reduction (UN/IDNDR).

In order to mitigate the risk associated to the recurrence of earthquakes, the GSHAP promotes a regionally coordinated, homogeneous approach to seismic hazard evaluation; the ultimate benefits are improved national and regional assessments of seismic hazards, to be used by national decision makers and engineers for land use planning and improved building design and construction.

The GSHAP was implemented in the 1992-1998 period and is coming to conclusion. All regional activities are now completed, and the publication of all regional results and of the GSHAP map of global seismic hazard is under way.

  Appendix I: Index, GSHAP Summary Volume, Annali di Geofisica, 1999

The Global Seismic Hazard Assessment Program, D. Giardini

Здесь можно скачать итоговую статью 1999 года координатора работ по GSHAP

 - Доменико Джиардини (pdf-6Mb)

Интервью некоторых исполнителей работ по GSHAP для журнала EOS:

New Map Lays Out Global Seismic Hazard Values (from EOS, Volume 80, December 28, 1999).

The first-ever quantitative Global Seismic Hazard Map, issued on December 16, pro­vides updated seismic hazard values for nearly half of the world's nations. The map also adjusts hazard values along some politically charged international boundaries where different methods for determining seismicity had led to dissimilar values on either side of a border.

Eight percent of Earth's land mass falls within a range of high or very high seismic hazard zones on the map. That hazard is defined as a 10% or greater probability of violent shaking - which is 25% or more acceleration of gravity - within the next 50 years. About 70% of the land mass lies in a low hazard range.

Despite the small percentage of land located in high hazard zones, many of the world's mega cities lie within red and brown bands on the map, which indicate high and very high hazard levels. Within these bands are a number of capital cities, including Caracas, Jakarta, Karachi, Katmandu, Istanbul, Manila, and Mexico City. The red and brown swaths cover a number of areas, including plate boundary regions along the Pacific rim from the Andes and U.S. west coast to Japan, the Philippines, and New Zealand. Another high hazard band stretches through parts of China, India, Iran, Turkey, and Europe.

"What we have at risk is not only population, but we have the entire functionality of the state, the government, and the economy," said Swiss Seismological Service Director Domenico Giardini, coordinator for the Global Seismic Hazard Assessment Program (GSHAP). The program produced the map as a demonstration project of the United Nations International Decade of Natural Disaster Reduction. That decade concludes on December 31.

While seismic hazard is significant, it does not necessarily translate into seismic risk, Giardini added. Hazard refers to a probability of ground shaking, and risk is a probability of damage that is obtained by combining the vulnerability of buildings with seismic information. he explained.

"This map only provides part of the story. You could easily live in Taiwan if you have a well-built house," he said, referring to a very high seismic hazard location.

"We would suggest that you think about it if you are going to live anywhere in the red or the brown zones," added Kaye Shedlock, a research geophysicist with the U.S. Geological Survey (USGS) in Golden, Colorado, who has served as GSHAP coordinator for the western hemisphere. She said people in these zones should consider the types of buildings they construct there.

Shedlock declined to indicate exactly where in the world the greatest seismic hazard exists. "Because seismic hazard calculations involve a great deal of statistical  manipulations, while I happen to know where the single highest value on that map is, what's the point? There is an uncertainty around it. So, by highlighting the very high hazard areas, we are saying these essentially have comparable hazard. These are the places you really want to think hard about living."

The map, which involved 500 scientists and engineers from around the world, and took 7 years to complete, incorporates a number of existing country maps. It includes data from seismic networks from around the world, global positioning system and geodetic monitoring, paleoseismology studies and geologic and tectonic framework studies, and histori­cal catalogs from China, Japan, and other regions. Even the Bible was consulted for historical data.

Seismic instrumentation has improved sig­nificantly in recent years, but relying only on newer measurements, and not on old cata­logs, would not account for some historically seismic areas where there may not have been earthquakes during the past several hundred years, according to Giardini.

Since some countries measure seismicity differently, and there had not previously been uniformly accepted standards to assess hazards, scientists involved with the mapping project wrangled over a number of issues - including how to describe ground motion and measure magnitudes, where to indicate that seismic zone boundaries might or might not go, and setting hazard values - to produce a map for improving seismic safety and building codes.

 The map measures peak ground acceleration (PGA), a common measurement of ground shaking, and provides seismic values for every tenth of a degree in every direction, which is about every 10 kilometers.

"For most countries in the world, new hazard maps are only produced when you get a big earthquake, and you realize that your houses were not well built," said Giardini.

For many countries, the GSHAP map marks a significant advance in determining their seismic hazard values.

"All of the African rift never had any seismic hazard assessed, and the hazard is quite high, actually," said Giardini. "For the first time, you have eight countries which never had a hazard map now have an official hazard map."

The map will alert countries to their vulnerability potential and should trigger some policy position adjustments and provide justification for better seismic monitoring networks both at national and regional levels, according to Isaac Nyambok, professor of geology at the University of Nairobi, Kenya, vice-presi­dent of the International Union of Geological Sciences, and GSHAP coordinator for parts of Africa.

The map "provides a sound basis for earthquake risk analysis for sub-Saharan Africa," he said. "The map can also be used as a first step in natural disaster mitigation and preparedness. It also broadly provides a basis for de­signing suitable building codes of earthquake intensity in specific regions. However, there are a few gaps in the data used which could have been closed if there were adequate financial resources for the project.

"If the map is further improved with information on horizontal acceleration and a larger scale used. it could form a basis of a legally binding document. In its present form. it is mainly a guiding document," he said.

In Australia, a new map produced according to national and GSHAP standards is colored primarily in swaths of green and yellow. which indicate low or moderate seismic haz­ard. The result of the new product is that the continent is now recognized to be more seismically active than it had been believed to be, said Giardini.

"The map is basically that in our current code. What it does do is give us a standard for comparison of the Australian hazard with that of the eastern U.S. and Canada, Europe. and parts of China and Africa which have similar tectonic settings. That allows us to compare our code practice with that of other countries," said Kevin McCue of the Austraian Geological Survey Organization. McCue. GSHAP coordinator for Australia, southwest Pacific, and southeast Asia, added, "my experience is that insurance rates won't change, though, if building codes are followed in design and construction that equalize the risk, then they should!"

 "The GSHAP map is a unique hazard map since it has been prepared through international cooperation using worldwide data, reliable data, and uniform procedure," said Mohsen Ghafory-Ashtiany, president of the International Institute of Earthquake Engineering and Seismology in Tehran, Iran, and head of GSHAP's regional working group for the Middle East. "The discrepancies that exist in the existing maps at the country's border have been eliminated."

For Russia, which produced one of the world's first general seismic zoning maps in 1937, the GSHAP world map has "mainly information significance, because the building codes in our country use Seismic Zoning Maps represented in the MSK-64 intensity scale (but not in PGA, as it is made in GSHAP); said Valentin Ulomov, head of the Laboratory of Continental Seismicity at the United Schmidt Institute of Physics of the Earth in Moscow, and GSHAP coordinator for Russia and now for the former Soviet Union.

Whole continents worked together on the map, but in some regions such as the Middle East, where politics are particularly sensitive, the scientific effort was more complicated.

Several years of effort were required to con­vince Turkey and Greece to agree to a certain middle level for seismicity in the Aegean Sea, where previously the level had varied just across borders.

And, three years of effort finally brought In­dia and China - which share a continent-to-continent collision zone boundary - to the same table, Giardini said. The result, according to several sources, was that India, which had lower hazard values prior to the mapping project, increased those values along the border with China and in the northern part of the coun­try, in order to fit more closely with hazard val­ues across the border in China. In some areas in India, the hazard value was increased by as much as 40%, when compared to a previous seismic study, one expert told Eos.

Modifications in hazard values may or may not generate internal political pressure within a country to revise building codes, according to Gail Atkinson, professor of Earth sciences at Canada's Carleton University in Ottawa, Ontario. The seismic hazard map, Atkinson explained, is only one input to what makes up a building code, and construction standards are also important.

"People should look at the differences [in revised hazard values] and understand the reasons for them and implications for the code," she said. "But it doesn't necessarily follow that there are major changes required in the code from the point of view of overall safety."

Terry Wallace, president of the Seismological Society of America, said that miscalculating hazard values might place a government that has to modify its values in a poor light and also have some economic implications.

"This match between India and China to some extent had to do with economic development," Wallace said, referring to the modification of seismic values in India.

He added that several of the required seismic hazard value changes on the GSHAP map were in developing nations that sometimes apply for loans from the World Bank and other institutions that need accurate hazard assessments.

"If you really modify your hazard values a lot, you need to immediately reevaluate all the critical facilities that you have. And that might explain the resistance in some places to really go out and play with the hazard. The seismic hazard is the value that is really used for critical facilities," said Giardini. He said that separate seismic studies are required as part of the planning and approval process for major infrastructure projects.

"As soon as you touch your hazard values a lot, you have to go out and check if safety is still there or not," Giardini added. "India is in the proc­ess now of checking what has to be reevaluated and what not, based on the new hazard level."

Shedlock said it is difficult to know what im­pact revised hazard values could have in dif­ferent countries. "In our own country, high hazard values, such as along the San Andreas fault system, have resulted in seismically-resistant building practices," she said. "The degree to which these practices are applied elsewhere are due to decisions made elsewhere."

"If it is a matter of raising India's level up, yes, it will affect a lot of things there that are planned and existing along the Himalayan foothills," said Leonardo Seeber, a research scientist at the Lamont-Doherty Earth Obser­vatory of Columbia University in New York. Seeber said the Himalayan region is one of the most dangerous places on the planet in terms of earthquakes. He added that one positive aspect about the mapping project is that it alerts people if there is a major hazards value mismatch in an area. "I would use the mismatch and unearth any problems with basic data or methodology," he said.

In the United States, new seismic hazard maps are required by law every 5 years, and the global project incorporates the USGS map. The United States operates sophisticated equipment that can produce a reasonably good global map, but by participating in this project the country not only gained a better understanding of worldwide seismicity, but also gained access to a global database and global analogs that are tectonically similar to U.S. regions.

"Since the United States encompasses every major tectonic terrain, we now have a far more complete database to look at our own parts of the country through analogies to other parts of countries that have had their large earthquakes during recorded history." said Shedlock.

"For the first time, we know where we stand globally. We have all been familiar with the San Andreas fault here in California, and the very good job Californians have done on the building codes. We now know how that com­pares directly with the rest of the world."

The International Lithosphere Program was the driving force behind the production of the map. with the assistance of a consortium of international organizations and institutions that included UNESCO, International Council of Scientific Unions (ICSU), European Council, USGS, Swiss Seismological Survey, and World Meteorological Organization.

Poster sized copies of the map can be obtained through the USGS by sending an e-mail with contact information to gshapmap@usgs.gov, and through the Swiss Seismological Service by sending an e-mail to sed@seismo.ifg.ethz.ch. For further information, visit the Web site: http://seismo.ethz.ch/GSHAP/. Randy Showstack, Staff Writer


Карта глобальной сейсмичности

 Карта глобальной сейсмичности


Карта глобальной сейсмической опасности, составленная на основе карт ОСР-97А и GSHAP и представленная в баллах шкалы сейсмической интенсивности MSK-64

Глобальная сейсмоопасность в баллах. 115 Кбайт

Поскольку для российских специалистов и, тем более, для работников страховых и перестраховочных компаний, наиболее приемлемым представлением степени сейсмической опасности является балльность, нами выполнен пересчет пиковых ускорений, указанных на карте GSH МAP, в баллы шкалы сейсмической интенсивности MSK-64. Приведенная ниже карта соответствует российской карте ОСР-97А, характеризующей 10%-ную вероятность возможного превышения (или 90%-ную вероятность не превышения) указанной на ней сейсмической интенсивности (в баллах) в течение 50 лет, и повторяемости таких сейсмических воздействий в любом пункте сейсмических зон в среднем один раз в 500 лет.



Под эгидой Европейской Сейсмологической Комиссии, в рамках Проекта 382 SESAME Международной программы геологической корреляции была составлена и в 2003 г. опубликована Карта сейсмической опасности Европейско-Средиземноморского региона. Редакторы карты - Д.Джиардини, М.Джименез и Г.Грюнталь.

Эта карта приведена ниже в несколько модифицированной компоновке с тем, чтобы указать имена основных вкладчиков в ее создание, среди которых от России - автор этих строк.  


European Seismological Commission

International Geological Correlation Program

Project no. 382: SESAME


February 2003

Сейсмическая опасность Европейскко-Средиземноморского региона. 234 Кбайт