1944 Argentina earthquakes

Posted by cdj On July - 24 - 2014

Written by Christina Bodnar-Anderson.

The 1945 Building Code for San Juan, Argentina has recently been donated to our library collection (Part One: and Part Two). This building code was elaborated in response to the M=7.4, January 15th, 1944, San Juan earthquake that killed approximately 8,000 of the 70,000 – 80,000 (Harrington) residents of the area at the time and also destroyed most of the structures in the city of San Juan. To our knowledge, this building code became the first municipal earthquake code in South America and was adopted by other areas in Argentina after its creation. Also, the formation of the National Seismic Prevention Institute (Instituto Nacional de Prevencion Sismica), INPRES, was initiated after the damaging 1944 earthquake in Argentina.

Damage from 1944 San Juan, Argentina earthquake (wikimedia.org)

Damage from 1944 San Juan, Argentina earthquake. (wikimedia.org)

A summary of seismological effects, loss of life and damages to structures from the January 1944 earthquake based on the article, “El Sismo de San Juan del 15 de enero de 1944” in Cienciae Investigación, Jan. 1945 by Horacio J. Harrington, a professor of geology at the University of Buenos Aires, was reprinted in Nature, May 1945. A description of the geological and seismological aspects of several earthquakes in this region is provided in Patricia Alvarado and Susan Beck’s paper, “Source characterization of the San Juan (Argentina) crustal earthquakes of 15 January 1944 (Mw 7.0) and 11 June 1952 (Mw 6.8).

The 1944 earthquake and resulting reconstruction may also have had political implications for Argentina, as Colonel Juan Domingo Perón used public esteem from the relief efforts to bolster his political career. A brief synopsis of political events after the earthquake can be read here. The entire article, “The Fragility of the Moment: Politics and Class in the Aftermath of the 1944 Argentine Earthquake,” by Mark Alan Healey is available for viewing here. UC Berkeley Structural Engineering Professor Emeritus, Vitelmo V. Bertero, was a resident of the San Juan region at the time of the earthquake and began his life-long interest and commitment to earthquake safety through improved engineering research, design and construction following the 1944 event.

The April 1, 2014 Chile Earthquake and Tsunami

Posted by cdj On April - 10 - 2014
Some reporting on the Mw= 8.2 earthquake that struck off the northern coast of Chile on April 1, 2014 have suggested that “strict earthquake hazard building codes” and thorough “disaster preparation” saved many lives. Although 928,000 people were evacuated, the death toll from the earthquake and tsunami remained very low (fewer than 10 deaths).

Adequate disaster preparedness can be understood as Chile has experienced more than a dozen M7.0 or larger earthquakes since 1973 as indicated in the image at the right from the USGS.

Tsunami disaster preparedness and early warning can, at least partially, offset human devastation. Tsunami forecast modeling and fast simulation abilities (as demonstrated by a propagating tsunami simulation video created by the National Weather Service’s Pacific Tsunami Warning Center for this Mw=8.2 coastal earthquake) have advanced rapidly in recent years.

Chile earthquakes >6.5, 1900-2012

Chile earthquakes >6.5, 1900-2012

Building codes and practices can also change rapidly from earthquake knowledge. The work of Professor Jack Moehle’s group of graduate researchers at UC Berkeley indicates the utility of post earthquake research in improving building codes and procedures. Three new reports by Pablo F. Parra “Lateral buckling in reinforced concrete walls” (UCB/SEMM-2014-01) ; Ahmet Cam Tanyeri “Collapse of a concrete wall building in the 2010 Chile Earthquake” (UCB/SEMM-2014-02) ; and Panagiotis H. Galanis “Development of collapse indicators for risk assessment of older-type reinforced concrete buildings” (UCB/SEMM-2014-03) directly address the seismic hazards of certain reinforced concrete design and detailing practices emerging from the 2010 Chile earthquake (Mw=8.8) and the Christchurch, New Zealand earthquakes of late 2010 and early 2011 (Mw=7.1 and Mw=6.3) and their remedy for risk reduction and safety.

Background and further engineering descriptions of the Chile earthquake can be viewed at the 2010 Chile earthquake clearinghouse site.

Strong-motion records from the magnitude 5.1 Mw earthquake which occurred 1 km South of La Habra in Southern California, at 9:09 pm on March 28, 2014, are available from the Center for Engineering Strong Motion Data (CESMD).

This earthquake was preceded by two foreshocks, the larger of M3.6 at 8:03 pm and several aftershocks. According to the Southern California Seismic Network, this sequence could be associated with the Puente Hills thrust (PHT). The PHT is a blind thrust fault that extends from this region to the north and west towards the City of Los Angeles. This fault has also been associated with the M5.9 1987 Oct. 1 Whittier Narrows earthquake.

Strong-Motion data from more than 270 structural and ground response stations of the California Integrated Seismic Network stations (CGS, USGS and SCSN) are available at this time for view and download. The largest peak ground acceleration of 0.71g was recorded at epicentral distance of about 5 km, in the city of Brea. As of this date, records from 16 stations recorded the earthquake with peak ground acceleration larger than 10%g, and 7 stations have recorded this earthquake within about 10 km from the epicenter.

CESMD staff at USGS and CGS

A Little Earthquake Engineering History

Posted by cdj On March - 6 - 2014
Title Page from Freeman's 1932 Report

Title Page from Freeman’s 1932 Book

The late 19th and early 20th century earthquake engineering and seismology careers of John Milne, Fusakichi Omori, Riki Sano, Arturo Danusso, Tachu Naito, Kyoji Suyehiro, Beno Gutenberg, Charles D. Derleth, and others are well documented today. (See for example: Reitherman, Robert K. for an international history, Geschwind, Carl-H. for a U.S. history, Bertero, Vitelmo V. for a practitioner’s recollections (chapter 1 in Earthquake Engineering – From Engineering Seismology to Performance-Based Engineering; restricted access by publisher), and the EERI Oral History Series for a Western U.S. states focused history). As far as it was possible for an exceptional person to exert influence and form on the nature and possibilities of earthquake engineering and engineering seismology in the 1920s and 1930s however, the accomplishments and influence of John R. Freeman may be second to none. Freeman was a 1876 graduate of M.I.T., a trained hydraulics engineer, who performed design and hydraulic engineering work on the Charles River (Boston, Ma), the Panama Canal (Panama-US), the Hetch Hetchy Water Supply System (California), the Yellow River (China) among other large projects in his early career.

In 1896 Freeman became President and Treasurer of the Manufacturers’ Mutual Fire Insurance Company (which evolved into today’s FM Global) where insured losses from fires following earthquakes drew his mature attention. The enormous insurance losses from the 1906 San Francisco Earthquake and Fire are associated with the world financial crisis of 1907 and the subsequent establishment of the U.S. Federal Reserve system. (See – Sean D. Carr and Robert F. Bruner, ‘The Panic of 1907: Lessons Learned from the Market’s Perfect Storm‘ (Hoboken, NJ: John Wiley & Sons, 2007).

Today John Freeman is primarily recalled through his Earthquake Damage and Earthquake Insurance (NY : McGraw Hill Book Company, January, 1932). This great 904 page book comprehensively reviewed the state of world’s knowledge regarding earthquake damage to the built environment and championed the mitigation of loss of life and property caused by the strong earth shaking during an earthquake and its secondary effects like fire, flood and landslides through better civil engineering practice. A similar but unpublished effort by the American Society of Civil Engineers following the Great 1923 Tokyo Earthquake and Fire, ‘Report of Special Committee on Effects of Earthquakes on Engineering Structures‘ foreshadowed Freeman’s book systematic catalog of earthquake damage observations and international seismic resistant engineering practice. Freeman’s 1932 book is widely considered a first, extensive textbook of natural hazard risk and earthquake resistant design that has helped to shape risk assessment and the natural hazard research programs at many universities until today.

To those following the sad and incredulous, much-publicized, criminal trial of Italian scientists for failing to provide an adequate, scientifically-assured, warning of the damaging April 6, 2009 earthquake in the Abruzzo region of Italy (M=6.3), following a cluster of smaller earthquakes in the region, the recently-announced guilty verdicts and sentencing have been followed by a letter from Professor Enzo Boschi of the National Institute of Geophysics and Volcanology (INGV), one of the guilty scientists, published in the 27 September 2013 (vol. 341) volume of Science under the heading “L’Aquila’s Aftershocks Shake Scientists“. In an odd turn, the NY Times blogs report at least one positive outcome from the Italian earthquakes in 2009 for the region – In November, four and a half years after the earthquake, L’Aquila inaugurated its international center for doctoral and advanced studies in physics, mathematics, computer science and social sciences, the Gran Sasso Science Institute (G.S.S.I.).


Lightly reinforced concrete frame with beam failures

Tensions surrounding publicly-funded research on potentially hazardous buildings in large modern cities during earthquakes persist in many places — in our case in California cities with building types long-known to pose some degree of potential hazards like some non-ductile or brittle, reinforced concrete frame buildings. The private property rights of building owners, commercial real estate prices and values, business opportunities for an aggressive engineering expertise, the public’s right to be informed of known social risk, the state of public schools and hospitals, and the legalities and politics implicit in modern seismic engineering research have re-emerged in a local controversy as reported in the the Los Angeles Times newspaper and more recently picked up at the NYTimes weekend edition. On January 19, 2014 UC Berkeley engineering professor, Jack Moehle, announced the project will give Los Angeles officials the addresses of about 1,500 old concrete buildings, many potentially at risk of collapse during a major earthquake. This list is now available in Los Angeles County and is described in a NEES posting. In March, 2014, the study authors released a broader, public-oriented, newspaper “guest editorial” on the subject of potential building collapse and remedial policy action in California.

For those interested in the more technical, recent developments in “Seismic Assessment of Existing Reinforced Concrete Buildings” (Part 1, Part 2, Part 3) these three sessions at the 2014 ACI Conference (March 23-27, 2014, Reno, Nevada, USA) may offer a good source of knowledge. ACI Committee 369 is working with the possibilities of ASCE 41 on the state of the art of seismic assessment of reinforced concrete buildings.

In 1998, the Earthquake Simulator Laboratory (PEER Labs) at the U.C. Berkeley Richmond Field Station hosted a series of model pile-foundation shaking table tests under contract to the California Department of Transportation (CalTrans). The tests consisted of model piles arrayed both singly and in groups, embedded in soft clay deposits, subjected to seismic base excitation. The model tests were conducted by U.C. Berkeley graduate students in geotechnical engineering, Philip Meymand (now with URS Consultantants), assisted by Thomas Lok (now a faculty member at University of Macau, China). UC Berkeley faculty principal investigators were Raymond Seed, Michael Riemer, and Juan Pestana-Nascimento. Don Clyde was the laboratory manager responsible for shaking table and data acquisition operations. Damage to pile foundations in some recent earthquakes (like the three images below) had alerted CalTrans bridge design engineers to the need for laboratory testing.

Collapsed Rio Bananito Bridge near Limon, Costa Rica, (M=7.6) 1991- CalTrans

Sheared Hollow Tube Pile under Warehouse, Kobe, Japan (M=6.7) 1995

Struve Slough Bridge (Calif.), Loma Prieta, (M=7.1) 1989

In order to expand a limited database of pile performance during strong shaking, to provide insight into a variety of seismic soil-pile-superstructure interaction (SSPSI) topics, and to generate a data set with which to calibrate advanced, nonlinear SSPSI analysis tools, the research project developed a specialized flexible wall test container to allow the soil to respond in the same fashion as the free-field, unencumbered by boundary effects. The shaking table reasonably reproduced both one-directional and two-directional input motions, and trends of model site response were consistent with free-field behavior; the motions amplified from base to surface and were coherent across the site. Site characterization included laboratory and in-situ testing to establish the undrained shear strength and shear wave velocity profiles. One-dimensional equivalent linear dynamic response analyses were successfully used to simulate the model free-field response, indicating that the model soil-container system adequately reproduced free-field site conditions.

Soil - Pile Testing Flexible Wall Container Setup on Shaking Table, 1998

Single piles were seen to respond with components of inertial and kinematic interaction, with the inertial components producing upper bound bending moments. The response of pile groups was highly frequency dependent. Pile cap and free field motion variations illustrated wave scattering effects and the necessity of developing modified foundation input motions for substructuring analyses. Moderate effects of pile cap embedment were observed, particularly in contributing to pile group rocking stiffness. The influences of two-directional shaking were seen to be minimal, as structural
inertial forces tended to resolve the motion to a strong axis for the simple single degree of freedom models tested.
For single piles, full perimeter soil resistance was not engaged, as the piles preferentially followed gaps developed in previous cycles. P-y curves derived from the static and seismic test data compared very well to those recommended by American Petroleum Industry (API). Degrading behavior due to hysteresis and gapping was observed, softening the near surface response below API stiffness values, indicating that gapping is an important feature to model. The application of system identification techniques yielded estimates of single pile and pile group flexible base frequencies and damping factors, which differed significantly from the fixed base assumption. Damping for the single piles and groups was computed to be a function of load level.

Estimates of pile head lateral stiffness derived from a suite of pile head loading tests differed over a wide range, and were a function of loading level and consequent soil-pile nonlinearity. The methods examined for computing dynamic stiffness from elastic theory provided unrealistically high estimates of stiffness for the model tests. ATC-32 chart solutions (and more detailed in ATC-32 Resource CD) provided marginally acceptable lower bound pile head stiffness estimates for very strong shaking events. [See also current : CalTrans Seismic Design Criteria 1.5.] The project’s final report, Seismic Response of Piles Research Project (developed from PhD dissertations), a WCEE conference paper describing the research, and several, very well-organized data reports and data files were prepared and archived at NISEE some years ago by the principal author. These reports, the experimental data, and some additional photographs of the project are provided again here.

Cities and natural disaster risks

Posted by cdj On September - 23 - 2013
In a new report, Mind the Risk, SwissRe, the large reinsurance company, observes the United Nations expects 6.3 billion people or 68% of the world’s population to be living in urban areas by 2050. Many of these high-growth cities are located on the coast and are threatened by floods, storms, earthquakes and other natural hazards. The growing concentration of people, assets and infrastructure in hazardous locations means that the loss potential in urban areas is high and rising. Insurance penetration is fairly low in most of the world’s fastest growing metropolitan areas. Using SwissRe catastrophe-modelling capacities, this report analyzes the five most severe natural disasters – river flooding, earthquake, wind storms, storm surge, and tsunami – confronting 616 of the world’s largest urban areas and assesses the potential impact on local residents and the economy. Tables can outline analytical results and details are provided in the report.

Mind the Risk -- SwissRe

Natural Disaster – Population Affected (millions)
River flood 379
Earthquakes 283
Windstorms 157
Storm surge 33
Tsunami 12
Municipal Region (City) – People affected, all five perils (millions)
Tokyo-Yokohama (JPN) 57.1
Manila (PHL) 34.6
Pearl-River Delta (CHN) 34.5
Osaka-Kobe (JPN) 32.1
Jakarta (IND) 27.7
Nagoya (JPN) 22.9
Kolkata (IND) 17.9
Shanghai (CHN) 16.7
Los Angeles (USA) 16.4
Tehran (IRN) 15.6

In a ‘Perspective’ article “Reducing Earthquake Risk,” published in the 6 September 2013 (Vol. 341 no. 6150 pp. 1070-1072) Science, Brian E. Tucker, noticing the same increasing urban earthquake risk writes that earthquake and tsunami risks, hazard monitoring and risk mitigation activities, and current research questions concerning some of the world’s seismic hot spots — South Central Asia, the Caribbean, Turkey, Tokyo, and Santiago (Chile) – produce an image of considerable progress in reducing losses due to earthquakes and tsunamis in some places in the world but of growing and evolving risks in others.

‘Open Access’ and Two New UCB Geo-Engineering Reports

Posted by cdj On September - 5 - 2013

Some twelve years before the University of California established its recent Open Access Policy for published research articles (July, 2013), the NISEE e-archive had been providing open access to peer-reviewed knowledge in earthquake engineering generated and published by UC Berkeley civil engineering faculty, students and visiting scholars through several technical report series (EERC ReportsSEMM ReportsUCB/GeoTech Reports — and, more recently, PEER Reports). The NISEE e-archive uses the lowest-priced, individual membership model possible (a one-time, $25.00 inscription fee that serves to limit frivolous or commercial downloads) for continuous access. Though often unrecognized, civil and environmental engineering faculty are, on occasions, well ahead of trends in academic and scholarly publishing.

This week, the UCB/Geotech report series in the NISEE e-archive added two new reports that document an extensive experimental and analytical study undertaken to develop a better understanding of the distribution and magnitude of seismic earth pressures on cantilever retaining structures that could explain the seeming anomaly of no significant damage or failures of retaining structures occurring in recent large earthquakes such as Wenchuan earthquake in China (2008) and the large subduction zone earthquakes in Chile (2010) and Japan (2011).

Seismic earth pressures on retaining structures in cohesionless soils by Mikola, Roozbeh Geraili; Sitar, Nicholas. UCB/GT-2013-01, University of California, Berkeley, Geotechnical Engineering, 2013. — This part of the study which included centrifuge model experiments and numerical simulations of the experiments focused on structures with cohesionless soil backfill.

Seismic earth pressures on retaining structures with cohesive backfills by Candia Agusti, Gabriel; Sitar, Nicholas. UCB/GT-2013-02, University of California, Berkeley, Geotechnical Engineering, 2013. — This report presents the results of centrifuge model experiments and numerical analyses of seismic response of retaining structures with cohesive backfill.

Concrete in Phoenix, AZ in October, 2014

Posted by cdj On August - 13 - 2013

Two sessions planned for the American Concrete Institute (ACI) Fall Convention in Phoenix, AZ (October 20-24, 2014) on Performance-Based Seismic Design: Lessons Learned from Recent Earthquakes – Part 1 and Performance-Based Seismic Design: Lessons Learned from Recent Earthquakes -Part 2 caught our attention.

Observations of the damaging behavior of reinforced concrete structural walls during the 2010 Chile and the 2011 New Zealand earthquakes, the performance of precast – prestressed buildings and concrete floor diaphragms, and comparisons with recent laboratory engineering tests conducted in the U.S. will be presented at these sessions. Rational, performance-based targets, implicit and explicit in the seismic provisions of ACI-318 Building Code Requirements, will likely be discussed. Several presenters have strong UC Berkeley earthquake engineering research connections.

Reliability and Optimization Meeting Proceedings

Posted by cdj On August - 7 - 2013
The NISEE library recently received a paper copy of “Reliability and Optimization of Structural Systems,” [editors Armen Der Kiureghian and Aram Hajian. Yerevan, Armenia ; AUA Press, 2012]. The text constitutes the recent Proceedings of the sixteenth working conference of the International Federation of Information Processing (IFIP) Working Group 7.5 on Reliability and Optimization of Structural Systems, Yerevan Armenia, June 24-27, 2012. Thirty-two technical papers are presented here, focused largely on risk, reliability and statistical model optimization in structural engineering, including seismic engineering. The source for this 261 page text is the American University of Armenia Press. Those interested in obtaining a copy (US $50) can contact Rubina Danilova at AUA Presss [email address is "rubina@aua.am"].
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