How to Detect, Diagnose, & Evaluate Earthquake Damage
Earthquake-Damaged Foundations, Structures, Chimneys, Mechanical Systems

EARTHQUAKE DAMAGED FOUNDATIONS - How to Evaluate and Diagnose Complex Combinations of Foundation Movement Cracks, Bends, Leans, or Shifts in Foundation Walls. Different causes of foundation leaning, bulging, cracking, creeping, tilting, sliding, or other movements, what they look like, how to fix them.
BUILDING DAMAGE ASSESSMENT & REPAIR - separate article
EARTHQUAKE DAMAGED CHIMNEYS - separate article
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP - separate article
Questions & Answers about how to recognize, diagnose, evaluate, and repair building foundation damage due to earthquake activity
References

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Foundation damage due to earthquake activity: this article discusses in detail the recognition of different types and causes of complex or combined building foundation movement and foundation damage. Earthquakes shake building structures in different patterns, sometimes unique to a particular quake. The basic movements are side to side, up and down, or a combination of these. Depending on which forces are exerted, buildings shift and structural components fail in different patterns. Here we describe different damage patterns observed in building foundations or strucures due to several different types of earthquakes.

Combinations of Building Foundation Movement due to Earthquake, Flood, or Storm Damage

The photographs of earthquake-damaged building foundations and structures shown here are rather dramatic (and terrible as there were certainly fatalities in these buildings). More subtle is the detection of small movements, not immediately obvious, that break gas mains or cause other dangerous building conditions following an earthquake.

We distinguish among vertical movement, horizontal movement, leaning, tipping, bending, differential and uniform settlement, earthquake and storm damage, and other foundation damage patterns.

This article series describes how to recognize and diagnose various types of foundation failure or damage, such as foundation cracks, masonry foundation crack patterns, and moving, leaning, bulging, or bowing building foundation walls.

Also see FOUNDATION CRACK EVALUATION for a discussion of the diagnosis of specific crack patterns in masonry foundations, and see FOUNDATION BULGE or LEAN MEASUREMENTS which explains a simple method for determining how much bulge or lean is present in a foundation or wall, then see FOUNDATION MOVEMENT ACTIVE vs. STATIC which helps determine if the foundation movement is ongoing, and see FOUNDATION DAMAGE SEVERITY for a discussion of just how much foundation movement is likely to be a concern.

To be used properly, this information must be combined with specific on-site observations at the particular building in order to form a reliable opinion about the condition of that building's foundation. Anyone having concern regarding the structural stability, safety, or damage of a building, foundation or other components, should consult a qualified expert. Photographs of types of foundation cracks and other foundation damage: we have a large library of photographs which we're in process of adding to this document. Pending completion of that work, contact the author if assistance is required.

At the Northridge Earthquake a sideways shift was visible on many buildings. Force was sufficient to shift some entire buildings sideways in distances ranging from just an inch or so (broken gas mains, gas explosions, fire, burst water mains) to distances up to eight feet (where buildings were leveraged sideways as supporting columns failed).

In the photo just below, lateral movement caused the failure of supporting columns. Some building sections collapsed straight down (photo below) while others were levered sideways by their supporting columns, moving sideways for a distance about equal to the height of the failing columns.

Our photo shows one of the bent, failed Lally columns. The building wall in the background of the photo was previously supported on top of this column.

Photograph of building damage near Los Angeles 1994 © Daniel Friedman

Vertical movement due to earthquake: The Northridge Earthquake in Los Angeles, California in January 1994 caused extensive damage as well as fatalities when buildings were shifted off of their foundations, leading to catastrophic collapse in some cases.

This photograph taken by the author at Northridge Meadows, a site of some of the worst fatalities, shows a section of building that collapsed straight down, compressing the first floor (and some occupants) to just a few inches.

The left portion of the photo shows a third floor balcony aligned with the second floor balcony of a building segment that did not collapse.

Earthquake resistant construction has as a primary objective to prevent just this sort of collapse, as an effort to reduce the number of injuries and fatalities from an earthquake.

Earthquake damaged bulding (C) Daniel Friedman

In this photograph, taken from the rear of the building above, the movement caused by the Northridge Meadows earthquake is more clearly demonstrated. Notice that the bent Lally column top shows that the column was hollow?

Structural engineers and experts with more experience than the author have examined this catastrophe. But we thought it worth noticing that some of the Lally columns that failed were hollow steel posts while others that remained standing at the same building project were ones that had been filled with concrete to resist bending. We wondered if the schedule-pressure of original construction at Northridge Meadows contributed to use of columns that were not what was called for.

Horizontal movement due to earthquake damage: The Northridge Earthquake in January 1994 also caused extensive damage when its lateral thrust caused some buildings buildings to be shifted off of their foundations.

This photograph shows an easy-to-determine case of significant lateral movement of a wood frame structure. Often an improperly secured crawl space cripple wall simply leaned over, levering the building to one side for a distance equal to the height of the collapsing (cripple wall).

In this case the collapse was of a wood-framed supporting wall, not a masonry foundation.

Combination of movements due to earthquake damage is demonstrated by this photograph of an un reinforced stone masonry foundation and wall home in California.

Un reinforced concrete structures are no longer permitted by California building codes for construction in areas of earthquake risk.

Manmade Earthquake Damage Sources: mining, oil or gas extraction & hydraulic fracturing or "fracking" activities can lead to earthquakes

In diagnosing earthquake type damage to buildings and their structures or foundations, note that even in areas that are not considered earthquake zones earthquakes may occur and may be traced to human activities. In March 2013 The New York Times reported on new earthquakes occurring at Loppersum in the Netherlands. Tremors have been recorded at a magnitude of 3.4 on the Richter scale. The Times reporter explained that after more than fifty years of natural gas extraction in the area, recent earthquakes have become more common.Quoting from the Times article:

Chief Seinen, a spokesman for the gas consortium known as NAM, said thte extraction had created at least 1,800 faults in the region's subsoil. 'These faults are seen as a mechanism to induce earthquake.' he said. [8]

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Frequently Asked Questions (FAQs) about earthquake damage to building foundations

Question: How to distinguish earthquake damage from other structural movement

Is there anyway to prove earthquake damage to a foundation? I have a single story ranch house built in the 1930’s that has recently been subjected to a mild earthquake in 2009 and 2011 (Midwest) both of which I felt the house shaking and was awaken from a sound sleep.

I have glass block windows that have started to splinter in one of the sections of my basement. Started first sometime after March 2011 when I notice the blocks were cracked.

A couple of weeks later I found glass fragments splintering from blocks. Been watching it periodically then forgot until yesterday I found several larger pieces of glass block…corner pieces on two of them. The mortar that holds the blocks in window area show cracking as well. This would indicate to me that there is still ongoing stress to my frame house which is causing continual splintering from the glass blocks.

I contacted a structural engineer who said it was not possible by looking at it to tell whether it was earthquake damage or not. He indicated soil testing would have to be done which would be very expensive.

I am concerned that my home or at least parts of it will collapse. I have contacted my insurance agent but they do not provide any services of which to tell if it is earthquake related or not.

If you have any referrals or helpful information, I would appreciate it. - Thank you,- B.O. in Missouri

Reply: Expert, experienced inspectors should be able to form a reasonably confident opinion about building damage, extent, and cause

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with the structure, its history, probable cause, and extent of impact on the building and its safety.

That said,

I'm in no position by mere email to argue with your engineer, but having inspected a very large number of earthquake damaged buildings (while serving the Red Cross) it is my OPINION that an inspector, contractor, home inspector, or engineer who has familiarity with earthquake damage in general as well as with specific earthquake activity in a particular area can recognize the presence of damage to the building structure and form an opinion about its general safety.

If inspected by an experienced diagnostician, typical causes of building structural movement can almost always be traced to a probable cause. In all cases of building foundation or other structural damage, understanding the cause of the damage is an essential part in planning for the necessary repairs.

For example, lateral or horizontal "shaking" by an earthquake is likely to damage all sides of a building while differential settlement due to soil problems tends to cause focused cracking, bending, leaning etc. If the cause of foundation damage is inadequate footings the repair requirements may be quite different from earthquake damage.

I am unclear why soil testing is a high priority step in evaluating the building;

The first order of priority, which should not be delayed, is an inspection of the property for safety and safe occupancy. Unless your property actually has no significant damage of any kind (regardless of origin), that inspection needs to be performed for your own safety regardless of arguments about the root cause.

Watch out - some safety defects that may be present following an earthquake as well as following other structural movements or damage can be subtle such as gas leaks and unsafe electrical wiring - even if the visible structural damage is minimal. At Northridge following the LA earthquake some buildings were very extensively damaged by the side to side movement of the earth during that event. But other buildings looked just about perfect, still sitting square on their foundations. Yet some of those "perfect-looking" structures were unsafe due to gas leaks that risked (and in some cases occurred) explosions and fires caused when subtle building movements damaged the utility lines.

Question: our newly built townhouse vibrates and shudders and we hear banging

Just moved in to a new build town house which vibrates constantly and suffers with shuddering (top/3rd floor more noticeable with windows also shaking). On ground floor can sometimes hear banging, like someone has jumped or dropped heavy object from above. On a main road but this does not always happen when heavy vehicle drives past. Also suffering noise from pipes/ventilation outlets. - Lesley Anne 12/29/2011

Reply:

Lesley:

If the building movement and noises you describe were due to an earthquake or ongoing temblers or tremors, you could quickly confirm that condition with your local emergency services departments and building department, or perhaps even neighbors, as other buildings would be experiencing symptoms as well.

If that is not the case, then what you describe sounds specific to your individual building. Because some building movements, vibrations, and sounds can be symptoms of a pending catastrophic collapse, it makes sense to ask for expert advice promptly. An expert will listen to your concerns and will make his/her own thorough inspection of the structure both outdoors and inside, looking for

Indications of actual building movement and related damage, such as cracks, separation of framing, sticking windows or doors, floors or ceilings out of level, walls out of plumb.

Indications of foundation movement or damage such as cracks, leans, bulges, bows.

The purpose of the initial assessment of building condition will focus on the discovery of signs of an immediate life safety hazard. If that sort of hazard is comfortably ruled out, what remains may be construction methods and materials issues to review with the building owner, contractor, or an independent professional structural or civil engineer who is familiar with the type of construction used for your building.

Keep us posted, what you learn may assist other readers.

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

[1] Arakida, Masaru. "Measuring vulnerability: The ADRC perspective for the theoretical basis and principles of indicator development." Measuring Vulnerability to Natural Hazards–towards disaster resilient societies, United Nations University Press, Tokyo (2006): 290-299.
[2] Comerio, Mary C. "Public policy for reducing earthquake risks: a US perspective." Building Research & Information 32, no. 5 (2004): 403-413.
[3] Kamat, Vineet R., and Sherif El-Tawil. "Evaluation of augmented reality for rapid assessment of earthquake-induced building damage." Journal of computing in civil engineering 21, no. 5 (2007): 303-310.
[4] Kovacs, Paul. Reducing the risk of earthquake damage in Canada: Lessons from Haiti and Chile. Institute for Catastrophic Loss Reduction, 2010.
[5] Mills, Evan, Evan Mills, and Ivo Knoepfel. Energy-efficiency options for insurance loss prevention. Environmental Energy Technologies Division, Ernest Orlando Lawrence Berkeley National Laboratory, 1997.
[6] Noji, Eric K., and Keith T. Sivertson. "Injury prevention in natural disasters. A theoretical framework." Disasters 11, no. 4 (1987): 290-296.
[7] Peek-Asa, Coritme, Jess F. Kraus, Linda B. Bourque, Dushyanthi Vimalachandra, Jenny Yu, and Jackie Abrams. "Fatal and hospitalized injuries resulting from the 1994 Northridge earthquake." International Journal of Epidemiology 27, no. 3 (1998): 459-465.
[8] John Tagliabue, Parts of Low Country Are Now Quake Country", The New York Times, 27 March 2013, p. A6.
[9] "A Foundation for Unstable Soils," Harris Hyman, P.E., Journal of Light Construction, May 1995
[10] "Backfilling Basics," Buck Bartley, Journal of Light Construction, October 1994
[11] "Inspecting Block Foundations," Donald V. Cohen, P.E., ASHI Reporter, December 1998. This article in turn cites the Fine Homebuilding article noted below.
Building Failures, Diagnosis & Avoidance, 2d Ed., W.H. Ransom, E.& F. Spon, New York, 1987 ISBN 0-419-14270-3
Domestic Building Surveys, Andrew R. Williams, Kindle book, Amazon.com
Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting:
A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.
Guide to Domestic Building Surveys, Jack Bower, Butterworth Architecture, London, 1988, ISBN 0-408-50000 X
"Avoiding Foundation Failures," Robert Marshall, Journal of Light Construction, July, 1996 (Highly recommend this article-DF)
"When Block Foundations go Bad," Fine Homebuilding, June/July 1998
"Concrete Slab Finishes and the Use of the F-number System", Matthew Stuart, P.E., S.E., F.ASCE, online course at www.pdhonline.org/courses/s130/s130.htm
Sal Alfano - Editor, Journal of Light Construction*
Thanks to Alan Carson, Carson Dunlop, Associates, Toronto, for technical critique and some of the foundation inspection photographs cited in these articles
Terry Carson - ASHI
Mark Cramer - ASHI
JD Grewell, ASHI
Duncan Hannay - ASHI, P.E. *
Bob Klewitz, M.S.C.E., P.E. - ASHI
Ken Kruger, P.E., AIA - ASHI
Bob Peterson, Magnum Piering - 800-771-7437 - FL*
Arlene Puentes, ASHI, October Home Inspections - (845) 216-7833 - Kingston NY
Greg Robi, Magnum Piering - 800-822-7437 - National*
Dave Rathbun, P.E. - Geotech Engineering - 904-622-2424 FL*
Ed Seaquist, P.E., SIE Assoc. - 301-269-1450 - National
Dave Wickersheimer, P.E. R.A. - IL, professor, school of structures division, UIUC - University of Illinois at Urbana-Champaign School of Architecture. Professor Wickersheimer specializes in structural failure investigation and repair for wood and masonry construction. * Mr. Wickersheimer's engineering consulting service can be contacted at HDC Wickersheimer Engineering Services. (3/2010)
*These reviewers have not returned comment 6/95

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.

Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd

Avongard foundation crack progress chart for structural crack monitoring
Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF] ISBN-10: 0471331724 ISBN-13: 978-0471331728
Building Pathology: Principles and Practice, David Watt, Wiley-Blackwell; 2 edition (March 7, 2008) ISBN-10: 1405161035 ISBN-13: 978-1405161039
Diagnosing & Repairing House Structure Problems, Edgar O. Seaquist, McGraw Hill, 1980 ISBN 0-07-056013-7 (obsolete, incomplete, missing most diagnosis steps, but very good reading; out of print but used copies are available at Amazon.com, and reprints are available from some inspection tool suppliers). Ed Seaquist was among the first speakers invited to a series of educational conferences organized by D Friedman for ASHI, the American Society of Home Inspectors, where the topic of inspecting the in-service condition of building structures was first addressed.
Design of Wood Structures - ASD, Donald E. Breyer, Kenneth Fridley, Kelly Cobeen, David Pollock, McGraw Hill, 2003, ISBN-10: 0071379320, ISBN-13: 978-0071379328
This book is an update of a long-established text dating from at least 1988 (DJF); Quoting:
This book is gives a good grasp of seismic design for wood structures. Many of the examples especially near the end are good practice for the California PE Special Seismic Exam design questions. It gives a good grasp of how seismic forces move through a building and how to calculate those forces at various locations. THE CLASSIC TEXT ON WOOD DESIGN UPDATED TO INCLUDE THE LATEST CODES AND DATA. Reflects the most recent provisions of the 2003 International Building Code and 2001 National Design Specification for Wood Construction. Continuing the sterling standard set by earlier editions, this indispensable reference clearly explains the best wood design techniques for the safe handling of gravity and lateral loads. Carefully revised and updated to include the new 2003 International Building Code, ASCE 7-02 Minimum Design Loads for Buildings and Other Structures, the 2001 National Design Specification for Wood Construction, and the most recent Allowable Stress Design.
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