|
|
| Hazard Photos Home | View Slides |
Earthquake Damage in Mexico City, Mexico, September 19, 1985 |
| On September 19, 1985, a magnitude 8.1 earthquake occurred off the Pacific coast of Mexico. The damage was concentrated in a 25 square km area of Mexico City, 350 km from the epicenter. The underlying geology and geologic history of Mexico City contributed to this unusual concentration of damage at a distance from the epicenter. Of a population of 18 million, an estimated 10,000 people were killed, and 50,000 were injured. In addition, 250,000 people lost their homes and property damage amounted to $5 billion. This set of slides shows different types of damaged buildings and the major kinds of structural failure that occurred in this earthquake including collapse of top, middle and bottom floors and total building failure. The effect of the subsoils on the earthshaking and building damage is emphasized. |
Graphic Showing Types of Buildings Damaged | |
 |
Medium-height buildings were the most vulnerable structures in the September 19 earthquake. Of the buildings that either collapsed or incurred serious damage, about 60% were in the 6-15 story range. The resonance frequency of such buildings coincided with the frequency range amplified most frequently in the subsoils. Diagram credit: C. Arnold, Building Systems Development, Inc. |
Diagram of Four Common Patterns of Building Failure | |
 |
Diagram of four common patterns of failure for severely damaged buildings. Main causes of building loss included: corner building failure (42%), collapse of intermediate floors (40%), collapse of upper floors (38%), `pounding:' (one building repeatedly striking another during earthquake vibrations) (15%), and foundation failure (13%). Diagram credit: C. Arnold, Building Systems Development, Inc. |
Failure of Top Floors, Hotel Continental, Mexico City | |
 |
Top failure of Hotel Continental (constructed in 1950). Top floors of buildings are particularly vulnerable because (1) upper floors are displaced more than ground level floors during earthquakes. (2) The resonance frequencies of the buildings coincide with the ground vibrations leading to large amplification of oscillations. (Such displacements often culminate in a whip-like effect.) (3) Upper floors often have smaller and weaker load-bearing components. (4) The length of this earthquake event gave time for development of torsional vibrations due to asymmetric distribution of masses and elasticity in the high-rise buildings. Photo credit: C. Arnold, Building Systems Development, Inc. |
Aerial View of Top Failure, Central Communications Center | |
 |
Aerial view of top failure of Central Communications Center. The twelve-story reinforced concrete structure housed the Ministry of Communications and Transport and the nation's main microwave transmitter. Failure of this structure precipitated a near total collapse of long-distance communications between Mexico City and the rest of the world and complicated the coordination of international rescue efforts. Photo credit: C. Arnold, Building Systems Development, Inc. |
Top-Floor Failure of Flexible Building Between Two Ridge Buildings | |
 |
This flexible commercial building was in a vice-like clamp between two rigid neighboring buildings. This pressure caused the upper part of the building to collapse at the level of neighboring structures' roofs. Photo credit: C. Arnold, Building Systems Development, Inc. |
Top-Floor Collapse Office Building, Mexico City | |
 |
This long office building shows characteristic top-floor collapse. The lower floors of the building were able to withstand the earthquake forces. About 40 percent of the total losses were due to collapses of topmost floors. Photo credit: Reinsurance Company, Munich, Germany |
Top-Floor Failure of Reinforced Concrete Building, Mexico City | |
 |
Top-floor failure of older reinforced concrete building. This building illustrates the `corner' effect that often causes particularly severe damage to buildings located on street corners. This increased vulnerability is due to the combination of different directions of vibration acting on the building and to the varying rigidity of facades and walls leading to neighboring buildings. Photo credit: C. Arnold, Building Systems Development, Inc. |
Mid-Floor Failure of Reinforced Concrete Building, Mexico City | |
 |
Mid-floor failure of Hotel de Carlo caused by pounding(repeated striking) from building at left. Note deflection of building at right. Construction is concrete frame. Here two buildings of similar height were built too closely together. The natural period of the buildings was close to the period of the earthquake causing lateral displacements large enough to allow them to `hammer' each other. Photo credit: C. Arnold, Building Systems Development, Inc. |
Closeup of Damage to Hotel de Carlo | |
 |
Detail of damage to Hotel de Carlo showing midfloor failure. Photo credit: C. Arnold, Building Systems Development, Inc. |
High-Rise Building Twisted in Earthquake | |
 |
Since it was inadequately stiffened, this high-rise building twisted excessively in the earthquake, forming the typical X-shaped cracks. An earthquake subjects the various components of a building to shear, bending, compression, and torsional forces. X-cracking is evidence that the earthquake energy has been dissipated in the shear walls. Photo credit: Reinsurance Company, Munich, Germany |
Earthquake Oscillations Cause Collapse of Vertical Supports | |
 |
The severe building oscillations deprived vertical supports of their load-bearing capacity despite strong steel reinforcements. Note absence of reinforcement cross ties in vertical columns. Photo credit: Reinsurance Company, Munich, Germany |
Parking Garage Collapse | |
 |
This multi-floor parking garage collapsed like a stack of cards while some of the neighboring buildings remained undamaged. Flat cement slab/waffle slab construction was the most vulnerable construction type with 85 total collapses during the 1985 quake. Photo credit: Reinsurance Company, Munich, Germany |
Bottom-level Failure Due to Weak First Floor | |
 |
Bottom-level failure of 7-story office building due to weak first floor. A relatively small percentage of partial building failures were lower floor failures. In `normal' earthquakes, however, this is the most common type of building failure since bottom floors typically have wide-open window areas and entrances with inadequate supports. Photo credit: C. Arnold, Building Systems Development, Inc. |
Building Sank into Liquefied Soil | |
 |
This combined 6-floor residential and commercial building sank more than one meter into the partially liquefied soil. Other buildings whose pile foundations rested on a hard layer of soil protruded from the surrounding terrain after the ground around the buildings subsided more than the buildings themselves. Photo credit: Reinsurance Company, Munich, Germany |
Collapsed School Building | |
 |
This is one of the many school buildings that collapsed in the earthquake. School buildings are particularly exposed to risk from earthquakes since they lack adequate stiffening in shear walls of large classroom areas. Fortunately, the earthquake occurred before school had started. Photo credit: Reinsurance Company, Munich, Germany |
Collapsed Floors Punctured by Load-Bearing Column | |
 |
In this building as in many others, the load-bearing column forced through the concrete floors as they collapsed around it. Severe resonance oscillations of the buildings caused strain at the juncture between columns and ceiling slabs; the concrete structure was destroyed and the steel reinforcements were strained until they failed. The vertical columns were either compressed or (as in this picture) punched through the heavy floors that collapsed around them. Photo credit: Reinsurance Company, Munich, Germany |
Total Collapse of Juarez Hospital | |
 |
Total collapse at Juarez Hospital. Four hundred medical personnel and patients were trapped in the maternity wing of the Juarez Hospital. Localized failures at the beam-to-beam joints of each floor caused the collapse of this reinforced concrete frame structure. Survivors were retrieved from the structure as late as ten days after the earthquake by tunneling through the debris between the floor slabs. Major portions of three of the city's largest hospitals collapsed burying some 1,200 people. Loss of these hospitals severely limited the city's ability to care for quake-injured patients. Photo credit: E.V. Leyendecker, National Bureau of Standards |
Totally Collapsed 21-Story Steel Frame Office Building | |
 |
Total collapse of 21-story steel frame office building. Note building standing in background. Many tall concrete structures whose designs met the requirements of the building code performed well. When the magnitude and duration of the quake are considered, the performance as a whole of the one million structures in the city was very good. Photo credit: E.V. Leyendecker, National Bureau of Standards |
Car Demolished by Debre | |
 |
Thousands of cars parked in the street or garages were damaged by falling debris. Many vehicles were totally destroyed. Falling debris also presented a hazard to pedestrians. It blocked streets preventing the passage of emergency vehicles. Photo credit: Reinsurance Company, Munich, Germany |
Totally Collapsed and Undamaged Office Buildings | |
 |
In contrast to the totally destroyed office building in the foreground, the 44-floor Torre Latinoamericana office building in the background on the right, remained almost totally undamaged, as it did in a 1957 earthquake. The building is a symmetrical steel frame structure built to resist earthquakes. It has 200 piles extending down about 35 meters to the topmost stable and load-bearing earth stratum. The tall transmission tower on the left had also been sufficiently designed to withstand large horizontal forces. Photo credit: Reinsurance Company, Munich, Germany |