bluuebunny/crossref_metadata_2025 huggingface dataset:
Accelerograms of the 1978 Tabas, Iran, Earthquake
Authors: Niazi Mansour
Published: July 2003

Three triaxial sets of accelerograms recorded in the near source region (within 50 km epicentral distance) of the September 16, 1978, Tabas earthquake (Ms 7.4 -7.7) are of great engineering importance. The distances of the recording sites from the nearest approach of the rupture surface are approximately 3, 17, and 28 km for Tabas, Dayhook and Boshrooyeh stations, respectively. The measured horizontal peak ground accelerations of 0.94 and 0.88 g at Tabas are higher than previously estimated. The peak vertical ground acceleration recorded at this station is 0.74 g. The normalized response spectra at these three stations are consistent with the Newmark-Hall elastic design spectra, suggesting that the latter adequately represent the spectral amplification factors at frequencies above 1 Hz. The main shock accelerogram at Dayhook exhibits at least three distinct events as indication of a complex source behavior. The widened spacing of these events on the Dayhook records further confirms that the rupture front moved northwestward away from this station and towards Tabas. The measured S minus trigger times at Tabas, Dayhook and Boshrooyeh stations are in conflict with the teleseismically determined epicenter, requiring it to move approximately 30 km to the southwest to about 33° 17′N, 57° 09′ E.
The Importance of Postearthquake Investigations
Authors: Hays Walter W.
Published: July 2003

Data and technical knowledge gained from postearthquake investigations of a dozen earthquakes since the 1964 Prince William Sound, Alaska, earthquake have significantly advanced the state-of-knowledge about earthquakes. These advances have motivated new and (or) improved programs, applications, and changes in public policy, including (1) the 1977 National Earthquake Hazards Reduction Program and its extensions, (2) earthquake prediction research, (3) deterministic and probabilistic hazards assessments, (4) design criteria for critical facilities, (5) earthquake-resistant design provisions of building codes, (6) seismic safety elements, (7) seismic microzoning, (8) lifeline engineering, and (9) seismic safety organizations. To date, the 1971 San Fernando, California, earthquake has triggered more rapid advances in knowledge and applications than any other earthquake.
The Local Recovery Process after a Major Natural Disaster
Authors: Rubin Claire B.
Published: July 2003

An organizing framework of the long-term recovery process was developed, after studying first hand how 14 U.S. communities recovered from a major disaster. The framework depicts the dynamic processes that contribute to an efficient local recovery, including the three key elements identified and the inter-relationships among them. The three key elements are personal leadership, ability to act, and knowledge of what to do. Although only one of the disaster events investigated during the four-year study period was a major damaging earthquake, the framework developed appears to be useful for understanding the aftermath of many types of natural disasters. Information about an effective recovery process should be factored into earthquake hazard mitigation and preparedness efforts because sooner or later, whether we are ready or not, we will be recovering from a major earthquake.
Reaching the Ethnic Minorities: Earthquake Public Education in the Aftermath of Foreign Disasters
Authors: Stallings Robert A.
Published: July 2003

Public education programs intended to increase individual and household preparations for earthquakes often prove to be disappointingly ineffective, especially in reaching minorities and ethnic groups outside the mainstream of community life. This paper argues that the success of such programs can be improved by understanding the ebb and flow of earthquake saliency as well as the complex social structure of our cities. In particular, earthquakes and other major disasters in the ancestral homeland represent “teachable moments” when receptivity to earthquake safety information may be especially high among members the ethnic community with a variety of psychological and personal links to that nation. The paper presents specific suggestions for taking fullest advantage of these teachable moments.
Post-Earthquake Performance of Pipelines in Coalinga
Authors: Isenberg Jeremy
Published: July 2003

In iron or steel pipelines subjected to ground shaking from wave effects, leaks are often related to corrosion and other types of chemical or physical deterioration associated with normal aging. This paper examines the performance of water, sewage and gas pipelines in Coalinga, California for five years prior to and two years after the May 1983 earthquake. It is found that water and sewer pipelines are suffering the effects of the earthquake two years later. Thus, in addition to causing prompt damage, the 1983 earthquake accelerated aging of pipeline systems which may have shortened their effective life and permanently increased maintenance costs.
Earthquake Damage and Loss Evaluation for California
Authors: Rojahn Christopher , Sharpe Roland L. , Scholl Roger E. , Kiremidjian Anne S. , Nutt Richard V. , Wilson R. R.
Published: July 2003

Consensus-opinion earthquake damage and loss estimates and companion loss estimation and inventory methdology have been developed for existing facilities in California. These data and methodology are needed to provide input into computer simulation methodologies developed by the Federal Emergency Management Agency (FEMA) that estimate the economic impacts of real or hypothetical California earthquakes on the state, region, and nation. Data and methodology developed include: consensus opinion damage-factor estimates (expected physical damage due to ground shaking); methodology to adjust damage-factor estimates to account for construction quality; methodology to estimate the effects of collateral hazards such as ground failure, fault rupture, and inundation; loss-of-function data and methodology to estimate the time it takes to restore damaged facilities to their pre-earthquake usability; methodology to estimate deaths and injuries; and inventory data and methodology for all types of existing industrial, commercial, residential, utility and transportation facilities in California. Damage-factor estimates are provided for Modified Mercalli Intensities VI through XII in the form of Damage Probability Matrices. Seven damage states are considered: 0%, 0-1%, 1-10%, 10-30%, 30-60%, 60-100%, and 100% damage. Loss-of-Function estimates, which specify the time required to restore a facility to 30%, 60%, and 100% of the pre-earthquake usability, are provided for these same seven damage states.
Lessons Learned from Recent Earthquakes and Research and Implications for Earthquake-Resistant Design of Building Structures in the United States
Authors: Bertero Vitelmo V.
Published: July 2003

Following an overview of the special problems inherent in the design and construction of earthquake-resistant buildings in regions of high seismic risk, the techniques that will be required to solve these problems in the U.S. are discussed. Some lessons learned from recent earthquakes, particularly those in Chile and Mexico in 1985, are discussed as are some results of integrated analytical and experimental research at the University of California, Berkeley. The implications of the ground motions recorded during the 1985 Mexican and Chilean earthquakes, the performance of buildings during the Mexican earthquake, and the research results previously discussed are then assessed with respect to seismic-resistant design regulations presently in force (UBC) as well as those formulated by ATC 3-06 and the Tentative Lateral Force Requirements recently developed by the Seismology Committee of SEAOC. The rationale for and reliability of the values suggested by the ATC for the “Response Modification Factor R” and by the SEAOC Seismology Committee for the “Structural Quality Factor Rw” are reviewed in detail. In the conclusion to the paper, two solutions for improving the earthquake-resistant design of building structures are proposed: an ideal (rational) method to be implemented in the future, and a compromise solution that can be implemented immediately.
Damage-Limiting Aseismic Design of Buildings
Authors: Park Y. J. , Ang A. H-S. , Wen Y. K.
Published: July 2003

A procedure for earthquake-resistant design is developed to limit the potential damage of buildings to a tolerable level. The procedure is based on the damage model developed earlier (Park and Ang, 1984) in which structural damage is expressed as a function of the maximum deformation and dissipated hysteretic energy. The tolerable degree of damage is defined on the basis of calibration with observed damages from past major earthquakes. The design method is examined in the context of reliability.
Advances in Design of Eccentrically Braced Frames
Authors: Popov Egor P. , Kasai Kazuhiko , Engelhardt Michael D.
Published: July 2003

Eccentrically Braced Frames (EBFs) have attained recognized status as a viable structural steel system for resisting lateral seismic forces. Sustained research at the University of California, Berkeley, since 1977 and numerous field applications provide a good database for their proper design. In this paper the different types of EBF are critically evaluated, and the kinematics of their inelastic deformation are examined with particular reference to the behavior of isolated short beam segments or links. Desirable link length and web stiffening are recommended. A preliminary design procedure for hand-calculation of EBFs is described and some suggestions for brace connection details are advanced.
Summary of Visit to U.S.S.R. On Seismic Construction: U.S. Delegation Trip Report
Authors: Liu S. C. , Astill Cliff J. , Masri Sami , Lu Le-Wu , Vanmarcke Erik H. , Jirsa James O. , Wyllie Loring A. , Trifunac Mihailo
Published: July 2003

The U.S.-U.S.S.R. Agreement on Housing and Other Construction was signed in Moscow, June 28, 1974, and includes a working group on “Construction in Seismic Areas”. As part of this protocol, exchange visits have occurred of working groups from the U.S. and the U.S.S.R. This report describes the most recent exchange which took place when the U.S. delegation visited the Soviet Union during October 12-22, 1986. The delegation visited construction sites and research institutes in Moscow, Tbilisi (Georgia), and Yerevan (Armenia). The technical focus of the visit was on building structure analysis and design, ground motion and geotechnical engineering issues, and experimental studies in design, repair, and retrofit.
Skopje, Yugoslavia: Seismic Concerns and Land use Issues during the First Twenty Years of Reconstruction following a Devastating Earthquake
Authors: Greene M. R.
Published: July 2003

This paper identifies some of the early decisions made after the devastating 1963 earthquake in Skopje, Yugoslavia and illustrates how those decisions shaped the city's reconstruction. The formation of a guiding committee, and a massive influx of outside aid contributed to a careful, thoughtful process for reconstruction. Also, postponement of city center redevelopment for two years and the early incorporation of seismic concerns meant that reconstruction would not just be rebuilding in the old pattern. The current development and construction process continues to take seismic concerns into account, particularly through an early required review of building location and size. Two significant problems have emerged from the long-term reconstruction—the explosive growth and boomtown atmosphere accompanying the post-earthquake rebuilding, and the dwindling resources available for rebuilding projects as more years pass from the earthquake.
The SMART I Accelerograph Array (1980-1987): A Review
Authors: Abrahamson N. A. , Bolt B. A. , Darragh R. B. , Penzien J. , Tsai Y. B.
Published: July 2003

SMART 1 is the first large digital array of strong-motion seismographs specially designed for engineering and seismological studies of the generation and near-field properties of earthquakes. Since the array began operation in September 1980, it has recorded over 3000 accelerogram traces from 48 earthquakes ranging in local magnitude ( ML) from 3.6 to 7.0. Peak ground accelerations have been recorded up to 0.33g and 0.34g on the horizontal and vertical components, respectively. Epicentral distances have ranged from 3 km 200 km from the array center, and focal depths have ranged from shallow to 100 km. The recorded earthquakes had both reverse and strike-slip focal mechanisms associated with the subduction zone and transform faults. These high quality, digital, ground motions provide a varied resource for earthquake engineering research. Earthquake engineering studies of the SMART 1 ground motion data have led to advances in knowledge in several cases: for example, on frequency-dependent incoherency of free-surface ground motions over short distances, on response of linear systems to multiple support excitations, on attenuation of peak ground-motion parameters and response spectra, on site torsion and phasing effects, and on the identification of wave types. Accelerograms from individual strong-motion seismographs do not, in general, provide such information. This review describes the SMART 1 array and the recorded earthquakes with special engineering applications. Also, it tabulates the unfiltered peak array accelerations, displays some of the recorded ground motion time histories, and summarizes the main engineering research that has made use of SMART 1 data.
Static and Dynamic Analysis of Multi-Story Buildings, Including P-Delta Effects
Authors: Wilson E. L. , Habibullah A.
Published: July 2003

The P-Delta phenomenon is an area of concern to structural engineers. Traditional methods for incorporating P-Delta effects in analysis are based on iterative techniques. These techniques are time-consuming and are in general used for static analysis only. For building structures, the mass, which causes the P-Delta effect, is constant irrespective of the lateral loads and displacements. This information is used to linearize the P-Delta effect for buildings and solve the problem “exactly”, satisfying equilibrium in the deformed position, without iterations. An algorithm is developed that incorporates the P-Delta effects into the basic formulation of the structural stiffness matrix as a geometric stiffness correction. This procedure can be used for both static and dynamic analysis and will account for the lengthening of the structural time periods and changes in mode shapes due to P-Delta effects. The algorithm can be directly incorporated into building analysis programs.
Performance of Steel Structures in the September 19 and 20, 1985 Mexico Earthquakes
Authors: Hanson R. D. , Martin H. W.
Published: July 2003

A description of the various types of steel structures built in Mexico City includes comparisons of the older types of steel construction with more modern buildings. Performance of steel buildings in the September 1985 earthquake was related to the local geotechnical conditions including foundation behavior. The collapses of the Edificio 21 Atlas and Conjunto Pino Suarez buildings raise important earthquake resistant design and research issues.
Dynamic Behavior of Nagawado Arch Dam in the Event of 1984 Naganoken Seibu Earthquake
Authors: Fujii T. , Egawa K. , Katayama I.
Published: July 2003

Nagawado dam, a slender arch dam of 155 m height and 355.5 m chord length, recorded maximum accelerations of 193 and 242 gal at the crown and the 1/4 point of the crest arch, respectively, in the September 14, 1984 Naganoken Seibu earthquake of magnitude 6.8. The maximum accelerations in the foundation rock were in the range of 21 to 31 gal. Fourier analysis and band-pass filtering of corrected accelerograms, and spatial and temporal diagrams of the computed displacements of the dam and the foundation indicate the significant structural modes of peak frequencies 3.3, 3.6, 4.7, and 5.5 Hz. These frequencies correspond to the antisymmetric first, the symmetric first, the symmetric second, and the antisymmetric second modes of the dam. The first three peak frequencies were in good agreement with the values of corresponding vibration modes obtained by a small-scale model test. The derived frequencies and vibration modes were found also compatible with the results of eigenvalue analysis of a preliminary 3-D finite-element model as a whole. Orthogonal sets of accelerograms recorded at the points across a treated fracture zone in the foundation rock did not record any significant relative motions.
The San Salvador Earthquake of October 10, 1986—Seismological Aspects and Other Recent Local Seismicity
Authors: White Randall A. , Harlow David H. , Alvarez Salvador
Published: July 2003

The San Salvador earthquake of October 10, 1986 originated along the Central American volcanic chain within the upper crust of the Caribbean Plate. Results from a local seismograph network show a tectonic style main shock-aftershock sequence, with a magnitude, Mw, 5.6. The hypocenter was located 7.3 km below the south edge of San Salvador. The main shock ruptured along a nearly vertical plane toward the north-northeast. A main shock fault-plane solution shows a nearly vertical fault plane striking N32\sz\E, with left-lateral sense of motion. This earthquake is the second Central American volcanic chain earthquake documented with left-lateral slip on a fault perpendicular to the volcanic chain. During the 2 1/2 years preceeding the earthquake, minor microseismicity was noted near the epicenter, but we show that this has been common along the volcanic chain since at least 1953. San Salvador was previously damaged by a volcanic chain earthquake on May 3, 1965. The locations of six foreshocks preceding the 1965 shock show a distinctly WNW-trending distribution. This observation, together with the distribution of damage and a fault-plane solution, suggest that right-lateral slip occurred along a fault sub-parallel with Central American volcanic chain. We believe this is the first time such motion has been documented along the volcanic chain. This earthquake was also unusual in that it was preceded by a foreshock sequence more energetic than the aftershock sequence. Earlier this century, on June 08, 1917, an Ms 6.4 earthquake occurred 30 to 40 km west of San Salvador Volcano. Only 30 minutes later, an Ms 6.3 earthquake occurred, centered at the volcano, and about 35 minutes later the volcano erupted. In 1919 an Ms 6 earthquake occurred, centered at about the epicenter of the 1986 earthquake. We conclude that the volcanic chain is seismically very active with variable styles of seismicity.
The San Salvador Earthquake of October 10, 1986—Geotechnical Effects
Authors: Chieruzzi Robert
Published: July 2003

Geotechnical effects generated by the October 10 earthquake were significant. Various types of observed ground failures include landslides, lurching or cracking, and differential fill compaction and settlement. Liquefaction and surface faulting were not observed. Poor compaction was responsible for many ground failures such as differential compaction/densification and settlement of embankment fills and fills placed in former deep barrancas. Foundation failures, if they occurred, were not observable at the time of the reconnaissance because of ongoing rescue and demolition operations and limited accessibility to collapsed buildings and major damaged areas. Preliminary assessment indicates that local geologic and soil conditions appear to have had some influence on the intensity of shaking and damage.
The San Salvador Earthquake of October 10, 1986—Review of Building Damage
Authors: Anderson Raymond W.
Published: July 2003

Damage to low-rise engineered buildings in San Salvador in the three to six-story height range was major and wide-spread. This can probably be attributed to the small natural periods of vibration associated with low-rise buildings and their response when interacting with the short-period and short-duration earthquake ground motion. Damage to high-rise buildings that have much longer periods of vibration was relatively minor. This paper reviews buildings that appeared to have performed well and describes the heavy damage that occurred to low-rise buildings that performed poorly, including examples of collapsed or partially collapsed buildings. Lessons learned or relearned from the San Salvador earthquake are summarized.
The San Salvador Earthquake of October 10, 1986—Detailed Evaluation of the Performance of Eight Engineered Structures
Authors: Lara Mauricio A.
Published: July 2003

Eight engineered buildings in San Salvador were selected to provide detailed descriptions of structures that performed both poorly and well during the 1986 earthquake. The buildings selected were all of reinforced concrete construction, both moment-frame and shear-wall, and were in the range of three to eight stories in height. The earthquake performance of the eight buildings ranged from the moderately severe structural and nonstructural damage to the El Salvador Sheraton Hotel, which will require retrofitting, to the negligible nonstructural damage to the VIP Building at the Sheraton Hotel complex. Comparison of the performance of the various buildings clearly shows that newer buildings, especially those built since 1973, revealed less damage than older buildings designed a-d constructed under less stringent codes.
The San Salvador Earthquake of October 10, 1986—Structural Aspects of Damage
Authors: Sauter Franz F.
Published: July 2003

The October 10, 1986 San Salvador earthquake caused extensive damage to one- and two-story bahareque-type dwellings and buildings, and the collapse of multistory engineered structures. The study of the effects of the San Salvador earthquake on buildings points out that poor quality materials and workmanship, as well as deficiencies in constructive details, are the cause of severe damage. However, it confirms once again that conceptual errors in design, including the selection of the lateral load resistant system, are the main cause of structural failure of buildings and engineered structures. It reiterates already well-known concepts, which are frequently forgotten by the professionals involved in the project and seismic design of modern buildings.
The San Salvador Earthquake of October 10, 1986—Performance of Lifelines
Authors: Morgan James R. , Swan Sam W.
Published: July 2003

Although the October 10, 1986 San Salvador earthquake was only a moderate event of magnitude 5.4 and the recorded ground motions had a relatively short duration, the high recorded peak accelerations caused substantial damage to lifelines. There was significant and widespread damage to buried lifelines. Long-distance telecommunications facilities were reportedly undamaged, but there was substantial loss of local phone service caused by damage to buildings, failures of equipment racks, and loss of emergency power (tilting of batteries). Power generating facilities (hydroelectric and geothermal) that supply electricity to San Salvador are located too far from the city to have been affected by the earthquake. Both 115-kV substations that serve San Salvador experienced a moderate level of damage, consisting mostly of ceramic column circuit breaker failures. As has been observed in past earthquakes, control and instrumentation systems and low-voltage power-supply equipment displayed an ability to withstand high ground accelerations.
The San Salvador Earthquake of October 10, 1986—Architecture and Urban Planning
Authors: Durkin Michael E. , Hopkins John
Published: July 2003

Major damage from the October 10 earthquake was concentrated in and around the capital city of San Salvador. Losses exceeded $900 million, or 25% of El Salvador's 1986 gross domestic product. Poor soil conditions, ineffective land use controls, and inadequate building practices combined with the severe shaking intensity to produce widespread damage to both engineered and nonengineered structures. Residential, institutional, and commercial buildings sustained heavy damage. Nonstructural damage and damage to building contents contributed to economic and operational loss. Government officials are making a deliberate attempt to incorporate new knowledge in reconstruction planning. However, recovery and reconstruction will be a slow process due to the current state of the economy.
Earthquake Characteristics and Damage Statistics
Authors: Thiel Charles C. , Zsutty Theodore C.
Published: July 2003

A simple Markov distribution relates the probability of occurrence of five discrete damage states for a specific building type in an earthquake. Within the model the damage distribution depends on parameters that represent the building's structural system, the matching of the site and building periods, and the site materials, and the site's acceleration. The constants in the model were determined using a maximum likelihood formulation and damage observations for a series of California and Chinese earthquakes. Model predictions of damage distributions agree well with reserved damage data not used in determining the constants. A maximum likelihood method allows determination of ground motion, attenuation, and/or earthquake moment magnitude from observations of damage for different types of structures located at diverse sites. A simple relationship exists for average damage estimate that closely matches historical observations.
Earthquake Safety: California's Comprehensive New Program
Authors: MacLeod J. D. , Scott S.
Published: July 2003

After many years of making progress slowly through ad hoc and piecemeal seismic safety measures adopted after damaging earthquakes, California has recently been moving toward more comprehensive seismic policy development, and in 1985 enacted the California Earthquake Hazards Reduction Act. The new law is a landmark in seismic policymaking, establishing a system of comprehensive and continuous planning, plan implementation, monitoring of results, and plan revision. It also adopted as a state policy goal the achievement of significant earthquake-hazard reduction by the year 2000. The program set up by the new law will further earthquake safety in six major areas: (1) existing development, (2) emergency preparedness and response, (3) new development, (4) long-term recovery, (5) education and public information, and (6) research and its application. The Seismic Safety Commission, an independent policy body that advises the Legislature and Governor on earthquake-related matters, was chosen to lead the program, working with other agencies representing a wide range of concerns. The first five-year program was published in September 1986, the “year 2” revision and progress report in September 1987, and the first follow-up supplement (for local government) in January 1988. The new program is already making respectable progress, although not as rapidly as the initial schedule called for.
The Whittier Narrows, California Earthquake of October 1, 1987—Early Results of Isoseismal Studies and Damage Surveys
Authors: Leyendecker E. V. , Highland L. M. , Hopper M. , Arnold E. P. , Thenhaus P. , Powers P.
Published: July 2003

Preliminary isoseismals for Modified Mercalli intensities are presented for the Whittier Narrows Earthquake. Isoseismals for intensities VI and lower are based on responses to a mail survey. Intensity VII and larger are based on a field survey of damage described in this paper. The maximum observed intensity of VIII was confined to Whittier. The shapes of the intensity contours compare favorably with the distribution of average peak acceleration data from the strong motion array in the greater Los Angeles area. The damage assessments appeared consistent with earthquake magnitude. However, the accelerations were higher than expected for the magnitude.

The building classification and survey strategies developed were tested and found usable and adequate for describing damage. With further refinement this system can be used to describe damage within a limited geographical area and in a format useful for correlations with strong ground motions and the Modified Mercalli Intensity scale.
The Whittier Narrows, California Earthquake of October 1, 1987—Social Aspects
Authors: Tierney K.
Published: July 2003

There were a relatively small number of fatalities and casualties in the Whittier Narrows, but social disruption was extensive. An estimated 10,000 households and thousands of businesses were affected. The earthquake also resulted in an increase in the need for mental health services. Due both to extensive mitigation and preparedness programs and to the moderate size of the event, the emergency response was, in general, well-managed. Nevertheless, important insights were gained on potential weaknesses in areas such as communication co-ordination. The response by local residents was generally positive and adaptive, but the need for improved public awareness and training was also evident. The earthquake demonstrated the importance of ethnicity as a factor that influences the public's response to the earthquake hazard. Although the long-term impact of the earthquake on the Southern California will likely be imperceptable, some segments of the population, such as low-income earthquake victims and businesses that were marginal before the earthquake, my experience difficulty recovering. The impact of the earthquake on seismic safety programs in the affected communities is an important topic warranting further research.
The Whittier Narrows, California Earthquake of October 1, 1987—Asbestos Hazards in Post-Earthquake Investigations
Authors: Chambers M. D.
Published: July 2003

Asbestos containing building materials (ACBM) can pose a significant hazard to design professionals and scientists engaged in post-earthquake building investigations. This paper discusses hazards of asbestos containing building materials (ACBM) susceptible to damage by seismic activity. Investigators must be aware of the potential for exposure to asbestos and other hazardous materials and how to protect themselves.
The Whittier Narrows, California Earthquake of October 1, 1987—Seismology
Authors: Jones L. , Hauksson E.
Published: July 2003

The October 1, 1987 Whittier Narrows earthquake ( ML = 5.9) was located at 34° 3.0′N, 118° 4.8′W, at the northwestern end of the Puente Hills. The sequence ruptured a small part, 4 km by 5 km, of a previously unidentified, buried, thrust fault that strikes east-west and dips 25° down to the north. This fault may be part of a large system of thrust faults extending across the entire east-west length of the northern margin of the Los Angeles basin. The focus of the mainshock is deep, at 14 ± 1 km. The largest aftershock ( ML = 5.3) produced mostly strike-slip movement on a steeply dipping, northwest plane, that bounds the mainshock rupture area to the west. Enhancement of the Los Angeles basin seismic network would facilitate investigation of the potential of these faults for moderate-sized or large earthquakes.
The Whittier Narrows, California Earthquake of October 1, 1987—Preliminary Analysis of Peak Horizontal Acceleration
Authors: Campbell K. W.
Published: July 2003

The Ml=5.9 Whittier Narrows, California, earthquake triggered several hundred accelerographs in the greater Los Angeles area. One-hundred and sixty-eight of these were used to develop attenuation relationships for peak horizontal acceleration. The analysis indicates that the attenuation of peak acceleration during the earthquake was generally consistent with that predicted from the attenuation relationships of Campbell (in press). However, the acceleration amplitudes were about 65-percent higher than predicted. An analysis of residuals clearly showed that the ground motions recorded during this earthquake were influenced by a complex interaction of source mechanism, building embedment, site geology, and geography. Source effects may have been responsible for the higher-than-expected accelerations as well as some of the observed azimuthal variation. The correlation of peak acceleration with geography may have been caused in part by the gross geologic structure of the region. Buildings with basements were observed to have lower accelerations than ground-level sites, consistent with previous results. Accelerations from rock sites—especially those from hard rock sites—were found to have lower amplitudes and greater variability than those from soil sites. The larger variability may be due in part to topographic effects. All sites located within about 20 km of the fault recorded about the same level of acceleration whether they were sited on deep soil, soft rock, or hard rock. Shallow-soil sites, however, had higher-than-average accelerations at relatively short distances, but lower-than-average accelerations at longer distances. Their behavior at long distances was more consistent with that of the underlying rock rather than that of the overlying soil, no doubt reflecting the longer wavelengths of the more distant ground motions.
The Whittier Narrows, California Earthquake of October 1, 1987—Simulation of Recorded Accelerations
Authors: Wald D. , Somerville P. G. , Burdick L. J.
Published: July 2003

We have simulated accelerograms from many of the strong motion stations close to the mainshock of the 1987 Whittier Narrows earthquake using a semi-empirical Green's function summation technique. This method allows gross aspects of the source rupture process to be treated deterministically using a kinematic model based on first motion studies, teleseismic modeling and the distribution of aftershocks. Stochastic aspects of the rupture process are then included to simulate irregularity in both rupture and slip velocity. Gross aspects of wave propagation are modeled using theoretical Green's functions calculated with generalized rays. Detailed aspects of the source radiation at high frequencies, as well as unmodeled propagational aspects such as scattering, are included empirically by using multiple recordings of a smaller Imperial Valley earthquake as empirical source functions. Our main objective is to see how well we can predict the peak ground accelerations, time histories and response spectra of ground motions of a moderate sized earthquake within the Los Angeles Basin having limited detailed source information. We find that the simulations predict the observations accurately enough to identify which phases and amplitudes in the observed data may be due to local site response rather than source or radiation effects. Comparisons between observed and simulated accelerograms for all the stations modeled are made using peak ground acceleration, and using time histories and response spectra for the stations that have been hand-digitized to date. The Bright Avenue Whittier station has the largest simulated peak acceleration, in agreement with the recorded peak acceleration data.
The Whittier Narrows, California Earthquake of October 1, 1987—Evaluation of Strengthened and Unstrengthened Unreinforced Masonry in Los Angeles City
Authors: Deppe K.
Published: July 2003

On November 15, 1987, the City of Los Angeles' Earthquake Division, launched a study of the performance of its strengthened unreinforced masonry buildings during the Whittier Narrows Earthquake. The objective of the study was twofold: (1) To analyze the damage to unstrengthened as well as to strengthened and tension-anchored-only buildings, and from that analysis (2) to determine the most effective ways of improving the design standards for strengthening unreinforced masonry buildings. The initial part of that objective has been completed, and the findings of that study are the primary basis for this article. Observed damage demonstrated a clear-cut need to improve certain aspects of the Code design standards for strengthened buildings; more importantly, however, it sent out warning signals to owners of unstrengthened buildings and only to a slightly lesser extent to owners of tensioned-anchors-only buildings, of the very serious need to fully strengthen their buildings and to improve on the low probability of those buildings surviving a major earthquake. The second part of the study's objective will require additional work, and the combined effort of the City of Los Angeles and the SEAOSC.
The Whittier Narrows, California Earthquake of October 1, 1987—Ticor Title Insurance Building Damage
Authors: Estes K.
Published: July 2003

The Ticor Title Insurance Building was a recently designed building that was significantly damaged by the recent October 1, 1987 Whittier Narrows Earthquake. The building experienced shear wall failures, floor and roof diaphragm failures, as well as failures of spandrel panel anchorages. The damage is chronicled by photographs in this article. This building, which is constructed chiefly of precast elements, shows the importance of tying together adequately different parts of a building. Special attention to building configuration, building deflection, connection and anchorage details is recommended.
The Whittier Narrows, California Earthquake of October 1, 1987—Performance of Buildings at California State University, Los Angeles
Authors: Taly N.
Published: July 2003

The Whittier Narrows earthquake (Richter Magnitude 5.9), which struck Southern California in the morning of October 1, 1987, caused some $20.5 million damage to various engineered buildings at California State University, Los Angeles and the death of a student due to a falling precast concrete panel. Peak ground acceleration of 0.39 g and a building response of 0.48 g were recorded in one of the affected buildings. The damage was both structural (cracking of reinforced concrete beams, columns and shear walls) and non-structural (cracked plaster and partition walls, dislodged and broken ceiling tiles, lights and other fixtures, damage to the science, computer and mechanical equipment and to utilities). A fire broke out in one chemistry laboratory and toxic combinations of chemicals were created by the spills in another chemistry laboratory. Shaking from the earthquake also aggravated existing friable asbestos contamination, forcing closure of one and portions of other buildings.
The Whittier Narrows, California Earthquake of October 1, 1987—Response of Lifelines and Their Effect on Emergency Response
Authors: Schiff A. J.
Published: July 2003

The response of lifeline systems was good, but there were component failures. Communication inadequacies did have a significant impact on the emergency response system. The dysfunction of lifelines, primarily power, communication, and natural gas systems put an added burden on the emergency response system and was the source of most fires. Damage and dysfunction included the frequently observed failure of ceramic elements on high voltage substation equipment, damage to large liquid storage tanks, and the saturation of the telephone system, including emergency response networks, with inappropriate calls. These hold the potential for compounding impacts after larger, more damaging earthquakes. The need to change operating procedures of some lifelines and to update emergency response public information is indicated.
The Whittier Narrows, California Earthquake of October 1, 1987—Response of Elevators
Authors: Schiff A. J.
Published: July 2003

The Whittier Narrows earthquake has been the first earthquake to affect a significant number and many of the same elevator systems that now conform to the more stringent code provisions introduced after the 1971 San Fernando earthquake. While the relative damage potential of the two earthquakes is not now known, much less manchine room and rope damage was observed. The incidence of counterweights coming out of their guide rails was much less than it was from the San Fernando earthquake but still quite common. The performance and operation of elevator earthquake protection devices, seismic switches and counterweight derail detection devices, did not fully meet expectations but they did significantly reduce damage and the potential for injury. There was some inconsistency in the triggering of seismic switches. The seismic performance of elevators suggest that several changes to codes should be considered including a requirement to report earthquake damage and prevent seismic devices from being reset by unauthorized personnel.
The Whittier Narrows, California Earthquake of October 1, 1987—Damage to the I-5/I-605 Separator
Authors: Priestley M. J. N.
Published: July 2003

The I-5/I-605 separator, a major nine span bridge, was severely damaged in the Whittier earthquakes. All columns of Bent 6, which is supported on the median strip of the Santa Ana Freeway (I-5) suffered shear failures, and the supported spans came close to collapse. Other minor damage included minor column hinging at more flexible bents, abutment pounding, and fracture of keeper plates at abutment rockers. Apparently much of this minor damage occurred during a major aftershock. Preliminary calculations indicate that the shear failures of Bent 6 resulted from disproportionate flexural and shear strengths of the columns, attributable to the working stress philosophy adopted in design, and the much greater stiffness of Bent 6 than adjacent bents. Movement joints with cable restrainers, at both ends of spans founded on Bent 6, make estimation of lateral load transfer from more flexible regions difficult.
The Mexico Earthquake of September 19, 1985—Past Decisions, Present Danger: An Historical Perspective on Ecology and Earthquakes in Mexico City
Authors: Tobriner S.
Published: July 2003

Why is one of the most populous cities in the world built on land which has a history of subsidence, seismicity, and flooding? Mexico City illustrates how early decisions in a city's history can create difficult conditions for building well and living safely. The Aztecs had little choice but to live on the muddy islands in Lake Texcoco which now lie beneath downtown Mexico City. But the Spanish did have a choice. By selecting the island capital of Tenochtitlan for their colonial capital they bequeathed to succeeding generations problems which were apparent to them almost immediately after they began construction. Their solution to the hydraulic problems of the site only exacerbated ecological and seismic problems which the inhabitants of Mexico City face today, and destroyed the reason the first settlers inhabited the Valley of Mexico.
The Mexico Earthquake of September 19, 1985—Self-Stimulated Seismicity for Noncharacteristic Earthquakes
Authors: Rosenblueth E.
Published: July 2003

A generalized linear version of Hawkes' self-exciting model serves to analyze and simulate foreshocks as well as background noise and aftershocks geneated at a tectonic fault. The model's inputs are magnitudes and occurrence times of characteristic earthquakes. It is partly validated and calibrated for decision making purposes using a physically based model and statistical data. The present model contains an excitation function relating earthquake magnitude with instantaneous increase in seismicity, and a memory function describing the decrease in seismicity with time. The excitation function depends markedly on the zone while the memory function is little sensitive thereto. Choice of the memory function and of its parameters rests on an optimum decision making approach. Results agree well with data from different parts of the world.
The Mexico Earthquake of September 19, 1985—Nonstationary Models of Seismic Ground Acceleration
Authors: Grigoriu M. , Ruiz S. E. , Rosenblueth E.
Published: July 2003

Characteristics of a nonstationary process obtained by modulating the amplitude and frequency of a stationary process differ from those of an oscillatory process. An accelerogram recorded in the soft soil of Mexico City during the 1985 earthquake serves to calibrate both nonstationary models. Responses of linear and nonlinear single-degree-of-freedom systems indicate that the process with modulated amplitude and frequency is preferable for reliability studies. Coefficients of variation of ductility demands of systems excited with accelerograms generated by the model with modulated amplitude and frequency are close to those corresponding to actual accelerograms.
The Mexico Earthquake of September 19, 1985—On the Seismic Response of the Valley of Mexico
Authors: Sánchez-Sesma F. , Chávez-Pérez S. , Suárez M. , Bravo M. A. , Pérez-Rocha L. E.
Published: July 2003

In order to explain damage and observed ground motions in Mexico City during the 1985 Michoacán earthquake, simultaneous consideration must be given to source, path, and site conditions. This is clear from teleseismic records and local vertical displacements. Incident waves had an important part of energy in the frequency band of 0.3-1 Hz. Damage distribution and observed motion in the lake bed zone cannot be satisfactorily explained using one-dimensional theory. The effects of lateral irregularities are required. To assess its effects we describe the stratigraphic setting of the valley and discuss some features of damage distribution with results for one- and two-dimensional wave propagation models. These are useful to establish on quantitative basis the importance of lateral heterogeneity.
The Mexico Earthquake of September 19, 1985—The Incident Wavefield in Mexico City during the Great Michoacán Earthquake and Its Interaction with the Deep Basin
Authors: Campillo M. , Bard P-Y. , Nicollin F. , Sánchez-Sesma F.
Published: July 2003

We used the vertical displacement records of the ground motion in Mexico City during the great 1985 Michoacan earthquake to identify the nature of the waves responsible for the heavy damage suffered by the town. The records at the different stations exhibit very similar waveshapes. A multichannel phase analysis shows the arrival, from the source zone, of a strong coherent wavetrain which represent the most of the energy incident at periods around 3 sec. We interpreted this arrival as the regional continental phase Lg. The study of other instrumental data in the period range relevant to the present investigation shows the efficiency of Lg propagation between the subduction zone and Mexico City.

We have computed the response to Lg waves of a sedimentary basin whose characteristics correspond to the deep basin beneath Mexico City. The amplification reaches a value of about 5. The results obtained are in good agreement with the response of the basin to a single obliquely incident plane wave. The durations of the theoretical signals are similar to those of actual observations at sites in the hills zone and in the intermediate zone.
The Mexico Earthquake of September 19, 1985—A Theoretical Investigation of Large- and Small-scale Amplification Effects in the Mexico City Valley
Authors: Bard P-Y. , Campillo M. , Chávez-Garcia F. J. , Sánchez-Sesma F.
Published: July 2003

The linear, large-scale and small-scale amplification effects in the Mexico City valley, related to both the surficial clay layer and the underlying thick sediments, are investigated with two-dimensional (2D) models and compared with the results of simple one-dimensional (1D) models. The deep sediments are shown to be responsible, on their own, for an amplification ranging between 3 and 7, a part of which is due to the 2D effects in case of low damping and velocity gradient. This result is consistent with the observed relative amplification around 0.5 Hz at CU stations with respect to TACY station. The amplification due to the clay layer is much larger (above 10), and the corresponding 2D effects have very peculiar characteristics. On the one hand, the local surface waves generated on any lateral heterogeneity exhibit a strong spatial decay, even in case of low damping (2%), and the motion at a given site is therefore affected only by lateral heterogeneities lying within a radius smaller than 1 km. On the other hand, these local 2D effects may be extremely large, either on the very edges of the lake-bed zone, or over localized thicker areas, where they induce a duration increase and an overamplification. The main engineering consequences of these results are twofold: i) microzoning studies in Mexico City should take into account the effects of deep sediments, and ii) as the surface motion in the lake-bed zone is extremely sensitive to local heterogeneities, 1D models are probably inappropriate in many parts of Mexico City.