earthquake risk management pilot project in quito,...

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Earthquake risk management pilot project in Quito, Ecuador

J.-L. Chatelain’.’, B. Tucker3, B. Guillier’,’, E Kaneko4, H. Yepes’, J. Femandez2, J. Valverde’, G. Hoefer3, M. Souris’*’, E. Dupérier’.’, T. Yamada4, G. Bustamante’ & C. Villacis3 ‘ IRD, Quito, Eciicidor: ’ Esciieki Politecriica Nticionnl, Quito, Ecuador; GeoHtiztirí1.v Iriteri~ariontil, Stíitforíl, U.S.A.: 40yo Corporation, Stiitnina, J q x i n ; 511ustre Municipio de Quito. Eciintlnr

Received 21 February 1995; accepted in revised form 24 October 1999

Key words: earthquake, Ecuador, Quito, risk mitigation, seismic scenario, vulnerability analysis

Abstract

An earthquake risk management project was conducted in Quito (Ecuador), consisting of evaluating the consequences of destructive earthquakes on the city. After choosing seismogenic sources that can affect the city, on historical and seismo- tectonics bases, intensities produced by these events were calculated, in order to estimate damages to the buildings and city networks. The scientific and technical studies were completed by interviews of the directors of the main city services in order to produce a vivid nontechnical description of the events during and at various time scales after the occurrence of one of the chosen earthquakes. Finally, recommendations were proposed to minimize the consequences of the next major earthquake on the city.

Introduction

The worldwide threat from earthquakes is growing: in 1900, me of every three large earthquakes killed humans, while today nearly two out of three are fatal. Earthquakes are nei- ther more frequent nor more powerful, rather, the number and size of vulnerable cities is growing. The world’s urban population is dramatically increasing: from about 30% of the world’s population in 1950 it is expected to reach roughly 50% by 2000. This growth is absorbed by cities becoming larger and more vulnerable: in 1950, only 25% of the world’s 50 largest cities were located within 200 kilometers of an historical magnitude 7 earthquake compared to about 50% in the year 2000.

As countries become more developed, earthquakes cause fewer deaths and greater economic losses: the 1987 Loma Prieta earthquake (U.S.A.) caused 62 deaths and $4.7 bil- lion of economic losses in and around San Francisco, while a similar sized earthquake in Spitak (Armenia) killed over 20000 people and $570 million of economic losses. The economic loss in Spitak represented 95% of Armenia’s GNP, while the loss from the Loma Prieta Earthquake represented only 0.2% of the United States GNP.

One means to reduce human and economic losses due to earthquakes is through planning for probable future events. It is possible to know where earthquakes will occur in &he long term, as well as to estimate th’eir magnitude. by cale- oseismicity, historical seismicity and tectonic studies, and thereby to evaluate their consequences.

The Quito earthquake risk management project is il pilot project launched to conduct an earthquake risk management study in a developing country. The purpose was to provide

direction to government officials, business leaders, and the public in general, to reduce damage and injury in the next major earthquake. To do this, three objectives were adopted: improve the understanding of Quito’s earthquake hazard; raise the awareness of the earthquake risk both within Ecuador and internationally; and design self-sustaining pro- krams for managing earthquake risk. The technical work involved institutions from Ecuador, Canada, France, Japan and the United States, in the fields of seismology, geology, soil mechanics, structural engineering, and city planning.

The project was divided into three phases. In the first, damaging earthquakes and their effects on Quito were an- alyzed. In the second, the impact on life in Quito during the month following one of these earthquakes was described in vivid, non-technical terms. Finally, based on the first two phases of the project, recommendations for managing Quito’s earthquake risk were formulated by a group of Ecuadorian and international specialists.

Why an earthquake risk management project in Quito?

Ecuador is located on the Northwestern part of the South-American plate, east of the boundary between the Nazca plate and South-American plate represented by the Colombia-Ecuador trench (Figure 1 ). Given this tectonic environment, three types of earthquakes affect the country: subduction earthquakes, shallow upper-plate earthquakes, and, marginally, volcano-related earthquakes that can have localized effects. The shallower subduction earthquakes OC-

cur along the coast. while the deeper ones (down to 300 km) occur iicross the o&ptry. The shallow upper-plate earthquakes, south of about 2.5OS. are concentrated under the

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& w e 1. Tectonic context of Ecuador. The Nazca plate and the Carnegie ridge are plunging beneath the South American Plate on which Ecuador is located. Arrows with numbers indicate the direction and velocity of plate convergence. Adapted From Bourgois et al. (1985).

coastal plain and the Subandean zone. To the north of that latitude, the shallow seismicity also occurs under the Andean cordillera.

The level of seismic activity in Ecuador is quite high. Earthquakes with magnitude 2 5.0 are frequent (Figure 2). During this century only, Ecuador has experienced 16 earthquakes with magnitude 3 7, including a magnitude 8.6 event in 1906 - the fifth largest recorded event in the world's earthquake history - which occurred offshore. The United States Geological Survey estimates a very high probability o f a great (magnitude greater than 7.7) earthquake, similar to the 1906 event, re-occurring off the Ecuadorian coast before the year 3,000 (Nishenko, 1989). During the past 4 centuries, earthquakes caused the death of over 60.000 people in the countcy, the vast majority of them in tGe Interandean Vallep where Quito is located. Out of the 23 events felt in Quito with an intensity of V I or bigger since 1541, 7 produced intensities of VI1 or bigger in 1587. 1627. 1698, 1755, 1797, 1859. and 1868 (Del Pino Lind Yepes. 1990). Quito has experienced damaging earthquakes occurring not only i n the immediate vicinity of the city, but also quite far w a y (for

example the 1797 earthquake occurred about I50 km to the south of Quito). It should be noted that damaging earthquakes have been separated by small intervals of time (9 years between the 1859 and 1868 events), or by as much as 168 years (between the 1587 and 1755 events). During the last century, the city of Quito has not experienced earthquakes with intensities1 of VI11 and above. This does not mean that such an earthquake cannot be expected in the future: for instance, no damaging earthquakes occurred during the 18th century, and then 2 damaging earthquakes occurred in the 1 13 following years.

The past damaging earthquakes occurred while Quito was quite different from the modern Quito. The city has changed significantly in the last 40 years. In that period. the population increased from 410000 to 1.3 million, with a considerable expansion of the city (Figure 3). This has resulted in increased urban densities, which. linked to expand- ing poverty, has resulted in an increase in poorly constructed buildings and development i n hazardous areas such as steep mountain slopes. In awtjon. high-rise buildings that did ncX exist in the 1950s have spread in the northern lower lands

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I / I 1 I 0 8.0- 8.5 Figtlre 2. Distribution of earthquakes with magnitude 2 5.0 in Ecuador. (A) Historical seismicity ( 1545-1960). (B) Instrumental seismicity (1961-1993). The tnajor earthquakes (magnitude 2 6.0) occur along the coast and in the Andes Cordillera. where most of them are located north of 2's. There is a pronounced gap of high magnitude events underneath the coastal plain. The deepest events occlIr eilst of the Cordillera, renecting the subduction process of the Nazca plate beneath the South American plate.

as a result of a more dynamic economy. Furthermore, the outcome of this dramatic growth is uncontrolled development and construction practices. Apart from the city's large modem structures, most dwellings in Quito were constructed without engineering guidelines. The Quito of today and to- morrow will respond to repetitions of the large historical earthquakes in very different ways than the Quito of the past.

It is expected that because of Quito's growth and earthquake history, the city's vulnerability will increase in the future unless concerted action is taken. To date, Quito has no standardized policy on building codes. While in 1990 the city began drafting a detailed development plan. in which earthquake hazards were taken into account. the inadequacy of available data hampered efforts to enhance the city's earthquake preparedness through planning guidance.

In order for the residents of Quito - including government officials, business leaders and the general public - to prepare for the next major earthquake, they must tirst under- stand the earthquake threat and the effects that a destructive

earthquake will have on Quito. Only then can Quito begin a risk reduction program to reduce damage and loss of life in the next major earthquake.

Description of the project

The project started in September 1992 and was completed by the beginning of 1994 (Escuela Politecnica Nacional. GeoHazards International, Ilustre Municipio de Quito, ORSTOM, OYO Corp., 1994a. 1994b). Adequate data in the fields of seismology, geology and soil engineering at the Escuela Politecnica Nacional of Quito, as well as a GIS and

project feasible. To provide objectivity, a group of international experts in

the various fields involved in the project was formed. Its task was to check and endorse the York done.

the data was also formed in order to insure that the results of the project could be used.

6' a computerized city data base at the Municipality made the

A group of potential users'of .*

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This group included representants of the local authorities, the main economical elements (e.g., banks, insurance, industry, and commerce) and the agencies responsible for the city services (e.g., water, electricity, sewage, and streets system).

First phase:$rture earthquakes and their efecfs 011 Quito

The objective of this phase was to determine the effects of several possible damaging earthquakes on the city. As the processing of the data and the methods used have already been described in details in a publication by Escuela Politec- nica Nacional, GeoHazards International, Ilustre Municipio de Quito, ORSTOM, OYQ Corp, (1994b) and Chutelain et al. (19961, we will only give here a rough sketch of how intensity distributions and their related effects have been obtained.

I . Siiectioti njseverui possilile rart/ì+ihe so~~rC'cs (¡ocdori. rrirrgnitrrde) thr t could tiireciteti die city From an analysis of the historical seismicity (Observatorio Astronómico de Quito, 1959; Vasek and Hanus, 1988; In- stituto GeofÍsico, 1992), microseismicity studies (Hall und

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Ramon, 1978; Hall et al., 1980, Yepes, 1982), and the distribution of tectonic and seismogenic structures of the country (Stauder, 1975; Barazangi and Isacks, 1976; Daly, 1989; Kanamori and McNally, 1982; Kelleher, 1972; Lonsdale, 1978; Mendoza and Dewey, 1984; Pardo-Casas and Molnar, 1987; Pennington, 1981; Kanus et al., 1987; Suarez et al., 1983; Winter, 1990), ten possible earthquakes with destructive potential for the city of Quito were identified (Figure 4). Three representative earthquakes were selected for detailed analysis (Figure 4):

(a) An inland earthquake of magnitude 7.3 and epicentral distance of 80 km from Quito, selected 8,s a representativ~ earthquake in the subandean region, in the zone of the 1987 earthquake.

(b) A coastal earthquake of magnitude 8.4 and epicentral distance of 200 km, selected because studies indicate a 60% probability of occurrence before the year 2000.

(c) A local earthquake of magnitude 6.5 and epicentrill distance of25 km. The 1990 Pomasqui earthquake indicated that the Catequilla fault is active, and the geometry of the fault indicates that it has the potential for generating a Ia@ magnitude earthqua& This earthquake is also modeling the

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Growth of Quito 1760 -1990

relations for the country. These relations were then corrected for application to the city of Quito.

2. Division of the city i r i m seìsinic Zones First, 4 main zones were determined based on topogra- phy, surface geology, seismic refraction tests, and electrical prospecting data (Municipality, EPN and water supply service unpublished data). The main zones were then subdivided using I 1 soil profiles going from 5 m down to 30 m deep (EPN, unpublished data) and over 2000 drillings from various sources (e.g., private consultants, municipality tiles, and EPN unpublished studies). We then estimated the depth of the bedrock using the programs SHAKE (Schnabel et al., 1972) and Namazu (Oyo Corp. unpublished program) by making vary the thickness of the deepest layer until no changes were observed in the ground amplification from records obtained at the surface during past earthquakes. We thus found 20 zones (Figure 5) with different characteristic soil columns.

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Figure 3. Spatial growth of Quito from 1760 to 1990. The last major destructive earthquake that hit Quito occurred in 1868, when the city was confined to approximately 4 km2. Since then Quito's area has grown roughly 70 times.

1587 earthquake located, possibly, on an active North-South trending fault.

These possible events represent earthquakes from each of the three regions of the South American upper plate in Ecuador described in the first section. The coastal earthquake is located at the boundary between the two plates and the inland and local earthquakes are located in the uppw* plate.

At the same time, twenty-three earthquakes that produced intensities of V I or greater during Ecuador's 460 years of written history, which includes 1104 seismic intensity observations (Observatorio Astronómico de Quito, 1959; In- stituto Geofisico, 1992). were used to establish attenuation

3. Evaliiatioiz of the intensity distribution ìn the cio! based on these zone to prepare seismic intensity distribution (SID) maps for each of the thee chosen earthqnakes Intensities in the 20 zones were computed, for each of the 3 hypothetical earthquakes, using the program SHAKE (Schnabel et al., 1972) using the input motion of known earthquakes recorded by the EPN accelerometers and the soil models that have been determined for each zone of the city (for more details see Chatelain et al. [1996]). Since there are no acceleration-related damage matrices for several types of structures found in Quito, such as adobe or self-made constructions, the ground shaking has been estimated using intensities rather than accelerations. Neumann's (1954) empirical relation has been used to convert into intensities the peak ground accelerations obtained with SHAKE. As a test of the method, intensities computed for the 1987 and 1990 earthquakes were compared with the intensities observed for these two events by EPN people. The intensity ranges for the three hypothetical earthquakes were the following:

Intensity range

Subduction earthquake 5.6 - 6. I inland earthquake 6.1 - 6.9 Local earthquake 6.3 - 8.0

The results for the hypothetical local event are mapped in Figure 6.

4. Eivrlurrtioiz ofthe locatioli and distribution of different striictural opes (builíliiz,gs, houses) throughout the city Because of the size of the city and the time limitations of the project, only the most populated urbnn portion of the city was studied in d.q3q4 using urban blocks as basic in- ventory elements in order to be able to enter the data in the municipulity GIS system. The study revealed that there were

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Figrire 4. Location of the ten most probable earthquakes that can affect the city of Quito represented by gray and black $jlled circles, which size i proportional to the possible magnitude of the events. The three black circles represent the earthquakes studied in the scenario (CE = coastal earthquakc LE = local earthquake; COE = continental earthquake).

fifteen main types of structures in Quito, characterized by their lateral load resistant system. Among those, each of the 9 most common types of buildings were subdivided in three categories, according to building heights: (1) low rise buildings (up to 3 stories), (2) medium rise buildings (from 4 to 7 stories), and (3) high rise buildings, (over 7 stories). Each block was classified according to its predominant structural system, i.e., the structural type that covered the greatest area of the block. The classification shows that (1) the most common type of structure in the city were reinforced concrete (RC) frames with flat slabs, (2) there is a belt around the city of non engineered structures and unreinforced masonry structures, and (3) adobe buildings are densely concentrated in the old part of the city. The distribution of the most common types of building is shown in Figure 7.

In order to estimate the structural vulnerability Ót the structures, some buildings that we considered 11s representative of each type of structures were evaluated according to the Quick Check recommendations of the ATC-22 (Applied Technology Council, 1989). Also, four adobe structures located in the old part of the city were revised, mainly un-

der shear conditions. Special structures such as hospitals schools, industrial facilities, as well as the sewage sys tem, water reservoir tanks, transmission towers, gas an( oil stations near the city, and the airport were inspectet individually with more scrutiny.

5. Evnlirntion of the consequences of the intensity distriOurion on the buildings and city sewices Physical damage caused by ground shaking was estimateLi using the damage probability matrices method provided b! the ATC-13 (Applied Technology a relationship between the dama Mercalli Intensity scale. The ex caused by ground shaking for eac ing damage probability matrices method defined in ATC- I -' (Applied Technology Council, 1985) for California. D m - ages to the main lifelines (streets, water supply, sew system, and electricity lines) were estimated using ATC-3 matrices (Applied Technology Council, 1991 ). The ATC- 13 and ATC-25 nqwiçes were calibrated for the Quito ilsing data of observèd damages by past earthquakes

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Figure 5. Distribution of soil zones in Quito. The 4 main zones (including the Panecillo hill, a small cangahua formation separating the southem and the northem parts of the lowlands) are shown in gray and black. They are subdivided into 10 zones on the basis of characteristic soil columns.

Figitre 6. Distribution of seismic intensities in Quito resulting from the local earthquake calculated within the soil zones of Figure 5. Because this hypothetical earthquake is located to the north of the city, the values of intensities are decreasing for the north to the south of the city, wich lateral variations due to the different types of soil.

1990) as data from Sauter and Shah (1978), Sauter (1979) and Whitman (1973). Following ATC-13, the dama, *e factor is defined as the ratio of the estimated cost of earthquake damages to the facility replacement value. We considered 7 states of damages: none, slight, light, moderate. heavy, major, destroyed. The method was first tested by comparing computed damages to observed damages for the 1987 earthquake, and then applied to each of the three hypothetical earthquakes. Finally, the time of rwovery for !ifelines,.was estimated.

The estimated damage distribution due to the local earthquake is shown in Figure 8. For this earthquake, structural damage is especially concentrated in the northern part of the city and on its eastern and western slopes. The low seismic resistance of self-built structures along with their critical

location on the slopes that surround Quito would produce heavy damage ratios (>20%). Adobe constructions, which are mainly concentrated in the center of the city, would suf- fer damage ratios from 10 to over 20%. Reinforced concrete (RC) structures, the most common type of construction in the northern part of the city would be less affected, with damage ratios ranging from 3 to 10%. However in the northernmost section of the city RC constructions would experience damage ratios over 20%. These results highlight that the possible consequences of an earthquake can be much more dramatic than what people and officials are expecting, especially compared to the damages resulting from the 1987 earthquake (Figurez). This was an important fact to show, as this event is the strongest so far that actual inhabitants of the

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Distribution of building categories in Quito

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Figure 7. Distribution of building types throughout the city of Quito. Adobe constructions are concentrated in the historical center of the city (centro histórico). The self-built constructions are located on the western and eastern flanks of the city, mainly to the South of the centro histórico, while concrete buildings are located in the lowlands north of the centro histórico.

city have experienced, and, moreover, is commonly believed as being the strongest that can affect the city ever.

Second Phase: a iizonth in Quito followiiig Lifiitiire earthquake (Escirela Pnlitécnicti N(iciona1, GeoHrrzards Interiiational, Ilustre Municipio de Quito, ORSTOM. OYO Corp.r 1994a)

The technical studies of this project; while providins-detailed estimations of the damage potential earthquakes would likely impart to Quito, may not effectively communicate the entire impact of such a disaster. In the second phase of the project, the technical studies were used as a basis to describe events following il. major earthquake and to illus- trate the scope of a disaster to the layperson. This earthquake

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damage scenario is vividly written using a nontechnicol vernacular for the purpose of helping government ofticinls. emergency service planners, business leaders, and the general public visualize the disruption caused by a future m:j,, earthquake. and provide the motivation and understandin,, required to address the earthquake threat. o

The severity and distribution of damage for this dc- scription were based on the technical from the tirst pllaSc previously described. The vulnerability of Quito's city services, facilities, and infrastructure was assessed thrpugh interviews with officials from seventeen different city organizations, including sewer, water, power, and transportation departments, Civil Defense, and fire and police departments.

The description (excerpts in annex 11, is based on the potential local earthquake, the most damaging of the three earthquakes considered in this project, although by no means the most destructive earthquake possible.

Third phase: Proposed recomrnendatiorts to minimize tlie consequences of the nexf major earthquake on the city

After the international advisory committee made the reviews and validation of the technical analyses, Ecuadorian and for- eign specialists in the fields of business and industry, city government, city planning, emergency services and lifelines met for a two-day workshop in Quito. After estimating seismic effects on such factors as production capacity, em- ployment, sales and services, the participants developed lists of specific recommendations within their field of expertise for reducing earthquake risks in Quito. For each recommendation, the participants described the steps necessary and the sources of funding, the responsible agencies, and expected start and completion dates. The primary recommendation was the establishment of a Seismic Safety Advisory Board, whose responsibility would be to review, revise and then ad- minister a Seismic Hazard Reduction Program. Other high priority recommendations include projects concerning existing facilities, new facilities, earthquake planning, earthquake recovery and further research needed to improve the findings of this project.

Conclusion

Because of this project, different scientific groups worked together towards a common goal, which would not have happened otherwise. It was an opportunity to gather and evaluate all earthquake-related data, most of them unpublished, for the country. It integrated existing research data and results that were previously scattered in different institutions, and presented them to leading intemational experts in each field, seeking their critique. Without this project. a scenario for Quito would have taken longer or would not have been produced at all. It is possible to achieve such a project locally, but that it is always hard to get the necessary coordination to perform a complex task such as this one in such a short time:@$o, through this project we were able for the first time to convince the Mayor Lind the other civic lenders that the city was really threatened by earthquakes.

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4 Observed distribution of damage after the 1987 earthquake

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Estimated distribution of damage for the hypothetical local earthquake

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Fiyirre 8. Distribution of damage to the buildings (A) observed after the 1987 earthquake. and (B) estimated for the local earthquake. Comparison between the two maps clearly demonstrate that the local earthquake would produce much more damage than the 1987 earthquake, which is commonly considered by people of the city as the strongest that could affect the city. The high damage ratio observed in the northern part of the city, including to concrete buildings. is due to the fact that the epicenter of the local earthquake was chosen North of the city. Other high damage ratios are observed in the centro histórico, where constructions are mainly made of adobe.

This project is only a beginning at defining Quito's seismic hazard. The results represent the state of knowledge presently available in Ecuador for evaluating the seismic risk in the Capital City. In addition, it is a diagnosis of the research needed for making more reliable seismic damage assessments, as well as for improving the awareness of seismic hazard in the city, among the local government, utility managers, emergency services, private sector and the people living in the city.

decades of work by the authors of this project in the fields of seismology, soil engineering and structural engineering, which was almost all published only as internal reports. They also represent five years of effort made by the Planning Service of the municipality to map the city on il computer with ORSTOM's GIS SavaneO(Souris et al., 1984-1994).

Without this previous information, it would have been impossible to accomplish our job in the short span of only 18 months.

One of the main goals of the experiment was to raise awareness about the seismic threat in Quito. This has been accomplished through a wide diffusion of the project. The linal report has been published in Spanish (Escuela Politéc- nica Nacional, GeoHazards International, Ilustre Municipio de Quito, ORSTOM, OYO Corp., 1996), and widely distrib-

These results are noteworthy becaùse they reflecr. uted in the city's community. The scenario properly speaking (i.e.. the description of the events that will follow a severe sarthquake) was published in newspapers, while the project has been presented in the municipality (Bustamante et ill., 1995) and civil defense (Yepes et al., 1994a) bulletins as well as i n the journal of the.&adorian ussociation of geography (Yepes et al.. 1994b). The project has been presented on tele-

vision, and there have been several interviews on television and radio of Ecuadorian scientists who were participating in the project.

Most of the highest priority recommendations were im- plemented. The municipality of Quito set up a Seismic Safety Advisory Board in 1997, which includes the Ecuado- rian scientists who were involved in the project, to work on the establishment of a specific seismic building code for the city. A project of retrofitting several schools of the city has been realized by EPN and GeoHazard International (Hoefer et al., 1995). The municipality of Quito has been convinced that a more thoroughly study of the city was needed and started a microzoning of the city in collaboration with EPN and ORSTOM.

The Quito pilot seismic scenario has also been presented in 22 meetings and workshops all over the world (e.g. Bus- tamante et al., 1993, 1994; Femandez et al., 1994, 1996; Tucker et al., 1995; Yepes et al., 1996). Its success, as well as the lessons learned from it, have been of great help to convince to set up and run a similar scenario in Kath- mandu (Nepal National Society for Earthquake Technology and GeoHazard International, 1999). Finally, the UN's ID- NDR RADIUS project became 'replicating' such projects in 9 cities in Asia, Africa and South America, including Gayaquil, the largest Ecuadorian city.

Acknowledgements

We thank the teams of Oyo Corporation, GeoHazards Inter- national, ORSTOM, Escuela Politécnica Nacional and IFEA for their contributions to this project. We thank B. Lortic, J. Tupiza, V. Tupiza and J. Vega for their help in drawing the maps. This project would not have been feasible without the ideas, the support, and the generosity of Dr Kunio Suyama, President of Oyo Corporation, who died before the project was completed.

Appendix 1. Excerpts from 'A Month in Quito Following a Future Earthquake'. (Escuela Politécnica Nacional, GeoHazards International, Ilustre Municipio de Quito, ORSTOM, OYO Corp., 1994a).

The earthquake strikes

It is just after 9:00 p.m. An afternoon of heavy rain has soilked the city; the streets are still wet. Residents of Quito nre relaxing with family and friends, having dinner, watch- ing television, or sitting and talking. Older children are studying for the next day at school while the younger ones ;ire asleep in bed. .

Suddenly there is a slight jolt,. then heavier stpking. Dishes quiver on dinner tables and windows rattle in their casings. The city trembles as the ground shakes violently. People are initially confused by the commotion, but then realize that Quito is experiencing a major earthquake.

Some people lose their balance: others are thrown to the tloor. Cabinet doors swing open, ejecting pots, pans and

dishes onto the floor in a terrible din. Pictures, lamps, and I

televisions fall to the floor, causing injury to some people ;Is they try to run from their homes to escape danger.

Northern Quito experiences the strongest shaking bt.- cause of its proximity to the earthquake source. The shaking is so strong that it becomes difficult to stand and nearly il,,. possible to walk. Many bookcases, refrigerators, stoves. other heavy objects overturn, pinning or crushing Some pee- ple beneath them. Self-built homes are devastated, lea\iin,, thousands homeless.

Shaking in the Centro Histórico is not as severe :ls il , the north. but still very strong. The abundance of the vlll- nerable adobe and unreinforced masonry buildings leavcx the area heavily damaged. Some adobe structures c o l l ; ~ ~ ~ ~ . especially those already damaged in past earthquakes uncl not properly repaired, trapping and killing those insiclp. Heavy, tile roofs collapse into homes. Narrow streets become clogged with rubble; frantic people search in tilt wreckage for buried loved-ones.

Landslides block Via Oriental and Via Occidental. Northern access to the city is interrupted by landslides on Panamericana Norte and the road to the Mitad del Mundo. Northwestern neighborhoods become isolated. Several main north-south avenues are blocked by damaged overpasses. Some motorists, unable to proceed, abandon their cars in the middle of the street, adding to the gridlock. Over a hun- dred obstructions in the roads of Quito make transit within the city and between northern, central and southern Quito almost impossible.

Water pipes throughout Quito break, especially at their rigid joints and in places where they cross filled quebradas. Some main sewer collectors, especially those located on the western slopes of the city, rupture, damaging overly- ing buildings and streets. Landslides along the Machangara River block sewage outlets. Structural damage to the central telephone building results in partial loss of telephone communication throughout Quito and to the outside world. Several distribution substations and transmission cables, especially those in the northern part of the city, are seriously damaged, plunging most of the city into darkness. Forty seconds after the start of the earthquake, the shaking stops.

One hour later

One hour after the earthquake has struck, uninjured citizells remove rubble by hand and with makeshift tools to free ~ i c - tims from underneath collapsed buildings, despite fear aftershocks. People try to locate family members and W- ply first aid, aided only with light from car headlights. ThC injured start to make their own way toward the hospital> and private clinics. Because of fear of aftershocks and [IlL'

unknown structural condition of their homes. many peoplc' who are uninjured and have no missing family member5 head towards open areas such as La Carolina. EI Ejido. La Alameda, and Fundeporte parks, A few take refuge i n wl- damaged churches, despite the danger of aftershocks. SolllL'

take advantage-@ the destruction iind confusion, and loo1 unprotected homes'and businesses.

r

I In several older homes, electrical wiring short-circuits, and fire spreads rapidly through the old, dry wood. Resi- dents attempt to extinguish fires, but some grow, threatening neighboring structures.. Thick adobe walls in many cases keep fires from spreading. The darkness of night is punc- tured by scattered flames. The fire department cannot attend to most of the fires because of lack of personnel, poor communication. blocked roads, heavy traffic, and lack of water-most water pipes have ruptured, cutting off supply, and many fire hydrants were out of service even before the earthquake.

As there are no automatic shut-off valves within the water supply system, large quantities of water are lost. Quito's water supply is cut off. Portions of the telephone system in operation are saturated by calls from people trying to reach relatives, friends, and public services.

The first day

During the first day after the earthquake, citizens realize that roads are blocked, and hence help may not come from rescue organizations in the near future; they begin to organize groups to search buildings for the injured and dead. Res- cue operations are hampered by lack of heavy equipment to move rubble.

Several roads cave into underlying sewers and quebradas, becoming' impassable. The city attehpts to locate heavy equipment to open blocked and damaged roads. Driving throughout the city is nearly impossible. Within neighborhoods, public transportation is nonexistent with the excep- tion of taxis, which charge many times more than standard rates. Because of damage to the power supply system, traffic lights are out of service, resulting in confusion and increased traffic congestion. Broken sewers Rood many vital underpasses.

Relief doctors and nurses cannot reach the hospitals because of road conditions and personal and family injuries, and hospital staffs become fatigued. Medical care is particu- larly difficult in hospitals without reserve water supplies and backup electrical generators. Undamaged public schools and military quarters are transformed into makeshift emergency health centers to accommodate the large number of injured.

Two days later

Two days after the earthquake, thousands of people are homeless; makeshift shelters are not able to accommodate them. Response workers are still attempting to rescue missing persons from beneath the rubble of collapsed buildings. A strong aftershock causes the collapse of a few buildings- damaged in the main earthquake, injuring or killing those taking refuge inside. Nonetheless, a few sleep in their damaged homes or on the street nearby to guard against looters. and some seek divine protection in churches. Many sleep in the parks, risking exposure and sickness from the rain and cold. Some with relatives, friends, or homes in other

I95

provinces leave the city, depriving Quito of badly needed emergency response and recovery professionals.

Most equipment and supplies for major utility repairs are unavailable. Inundation of sewage and rain clogs many utility tunnels, damages roads, and makes repairs cumbersome and unpleasant. At the central communications building, attempts to make equipment repairs and reestablish telephone service fail, as the staff is unwilling to enter the building for fear of aftershock. While EMETEL restricts telephone access to government and emergency service facilities, these organizations find radio communication more . reliable. Financial insti tutions abroad attempt unsuccessfully to communicate with business partners in Quito.

One week later

One week after the earthquake, workers remove the last victims using heavy lifting equipment. Undamaged public school buildings and other temporary shelters are full, and many people are living on the streets and in parks.

Trash and human waste collects in streets and alleys. Many residents develop gastro-intestinal diseases as a result of consuming contaminated food and water.. .

Health care in Quito's clinics and hospitals improve after medicines and personnel arrive from neighboring cities. Still, the death toll increases. As the morgues are full, dead bodies line hospital hallways. Health officials make plans to open mass graves.. .

One month later '

One month after the earthquake, shelters are still full, and many are still living in tent cities. The only improvement in living conditions many have seen is that the plastic or card- board tents they built themselves were replaced with canvas tents.

Because of the difficult work of visually detecting sewer ruptures, the sewage system will not be fully operational for some five months. Contingency plans are established to dig pits throughout the city, which will serve as interim dumps.

Officials start defining reconstruction plans. Recovery assistance is insufficient, as national agencies do not have enough funds to help victims.

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L 1999 vol. 49 no. 2

.An International Journal on Human Geography and Environmental Sciences,

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3 O NOV. 2l" hn" 9 4 , 5 3 3 Armero (Colombia) 13 november 1985.

IRD

Apartaba, 1 7- 12-857 -~Qaumntation

Qito-Equa- Special issue on: Urban hazards and risks; consequences of large eruptions and earthquakes

Edited by: Jean-Claude Thouret

Kluwer Academic Publishers Dordrecht/Boston/London

Geo Journal Volume49 no.2 1999 .

Special Issue on: Urban hazards and risks; consequences of large eruptions and earthquakes Edited by: JEAN-CLAUDE THOURET

Urban hazards and risks; consequences of earthquakes and volcanic eruptions: an introduction Jean-Claude Thouret 131-1 35

Megacities and natural disasters: a comparative analysis

Urban steeplands in the tropics: an environment of accelerated erosion Avijit Gupta, Rafi Ahmad

Monitoring of hazards and urban growth in Villavicencio, Colombia, using scanned air photos and satellite imagery Jan J. Nossin

, James K. Mitchell 37-1 42

43-1 50

51-158

The use of 3-D mapping in geological research and risks analysis: evaluation of a water supply project in the Kathmandu-Melamchi Area C. Eardinet, E. Bournay

Omkar M. Shrestha, Achyuta Koirala, Jörg Hanisch, Klaus Busch, Martin Kerntke, Stefan

159-1 63

A geo-environmental map for the sustainable development of the Kathmandu Valley, Nepal - Jäger 165-1 72

Lahar hazard micro-zonation and risk assessment in Yogyakarta city, Indonesia Franck Lavigne 173-1 83

Earthquake risk management pilot project in Quito, Ecuador J.-L. Chatelain, E. Tucker, B. Guillier, F. Kaneko, H. Yepes, J. Fernandez, J. Valverde, G. Hoefer,

A geographic approach of the global vulnerability in urban area: case of Manizales, Colombian

M. Souris, E. Dupérier, T. Yamada, G. Eustamante, C. Villacis 185-1 96

Andes Anne-Catherine Chardon 197-21 2

Political and scientific Uncertainties in volcanic risk management: The yellow alert in Quito in October 1998

Analysis of the institutional and social responses to the eruption and the lahars of Mount Pinatubo volcano from 1991 to 1998 (Central Luzon, Philippines)

Pascale Metzger, Robert D’Ercole, Alexis Sierra 21 3-221

Frédéric Leone, Jean-Christophe Gaillard 223-238

Coveri//ustration: Armero (Colombia), before and after the 13 November 1985 lahars from Nevado del Ruiz (courtesy and copyright:

IGAC 1985, Instituto Geografico Agustin Codazzi, Bogota, Colombia).

earthquake risk management pilot project in quito,...

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