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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.

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.

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

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.

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.

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.

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.

Questions & Answers regarding this article

Questions & answers about how to recognize, diagnose, evaluate, and repair building foundation damage due to earthquake activity.

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FOUNDATION CRACKS & DAMAGE GUIDE
  BRICK FOUNDATIONS & WALLS
  BUCKLED FOUNDATIONS due to INSULATION?
  CRAWL SPACES
  EARTHQUAKE DAMAGED FOUNDATIONS
  FOUNDATION CONSTRUCTION TYPES
  FOUNDATION INSPECTION METHODS
  FOUNDATION FAILURES by TYPE & MATERIAL
  FOUNDATION FAILURES by MOVEMENT TYPE
  FLOOD DAMAGE TO FOUNDATIONS
  FOUNDATION DEFECTS OF OMISSION
  FOUNDATION CRACK EVALUATION
    CRACK MONITORING Methods
    DIAGONAL FOUNDATION CRACKS
    HORIZONTAL FOUNDATION CRACKS
    SHRINKAGE vs EXPANSION vs SETTLEMENT
    Sinkholes & Building Damage
    Thermal Expansion Cracking of Brick
    VERTICAL FOUNDATION CRACKS
  FOUNDATION BULGE or LEAN MEASUREMENTS
  FOUNDATION DAMAGE REPORTS
  FOUNDATION DAMAGE SEVERITY
  FOUNDATION INSPECTION STANDARDS
  FOUNDATION MOVEMENT ACTIVE vs. STATIC
  FOUNDATION REPAIR METHODS
  PIER or PILE FOUNDATIONS
  SITE FACTORS AFFECTING FOUNDATIONS
  SLAB CRACK EVALUATION
  SLAB CRACK REPAIR

• "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.

• Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
• Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
• The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for certain articles found at this website. All rights and contents to those materials are ©Journal of Light Construction and may not be reproduced in any form.
• Appliances and Home Electronics, - energy savings, U.S. Department of Energy
• Avongard foundation crack progress chart for structural crack monitoring
• Basement Moisture Control, U.S. Department of Energy
• 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
• The Circular Staircase, Mary Roberts Rinehart
• Construction Drawings and Details, Rosemary Kilmer
• Crawl Space Moisture Control, U.S. Department of Energy
• 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.
• 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)
• "A Foundation for Unstable Soils," Harris Hyman, P.E., Journal of Light Construction, May 1995
• "Backfilling Basics," Buck Bartley, Journal of Light Construction, October 1994
• "Inspecting Block Foundations," Donald V. Cohen, P.E., ASHI Reporter, December 1998. This article in turn cites the Fine Homebuilding article noted below.
• "When Block Foundations go Bad," Fine Homebuilding, June/July 1998
• Energy Recover Ventilation Systems for Buildings, U.S. Department of Energy
• Energy Savings Methods: Whole House Systems Approach, U.S. Department of Energy
• Historic Preservation Technology: A Primer, Robert A. Young, Wiley (March 21, 2008) ISBN-10: 0471788368 ISBN-13: 978-0471788362
• Log Homes: Minimizing Air Leakage in Log Homes, U.S. Department of Energy
• Log Homes: Controlling Moisture in Log Homes, U.S. Department of Energy
• Log Homes: Log Home Design, U.S. Department of Energy
• Moisture Control in Buildings, U.S. Department of Energy
• Moisture Control in Walls, U.S. Department of Energy
• Quality Standards for the Professional Remodeling Industry, National Association of Home Builders Remodelers Council, NAHB Research Foundation, 1987.
• Quality Standards for the Professional Remodeler, N.U. Ahmed, # Home Builder Pr (February 1991), ISBN-10: 0867183594, ISBN-13: 978-0867183597
• Natural Ventilation for Buildings, U.S. Department of Energy
• R-Value of Wood, U.S. Department of Energy
• Spot Ventilation for houses, U.S. Department of Energy
• Slab on Grade Foundation Moisture and Air Leakage, U.S. Department of Energy
• Straw Bale Home Design, U.S. Department of Energy provides information on strawbale home construction - original source at http://www.energysavers.gov/your_home/designing_remodeling/index.cfm/mytopic=10350
• More Straw Bale Building: A Complete Guide to Designing and Building with Straw (Mother Earth News Wiser Living Series), Chris Magwood, Peter Mack, New Society Publishers (February 1, 2005), ISBN-10: 0865715181 ISBN-13: 978-0865715189 - Quoting:
  Straw bale houses are easy to build, affordable, super energy efficient, environmentally friendly, attractive, and can be designed to match the builder’s personal space needs, esthetics and budget. Despite mushrooming interest in the technique, however, most straw bale books focus on “selling” the dream of straw bale building, but don’t adequately address the most critical issues faced by bale house builders. Moreover, since many developments in this field are recent, few books are completely up to date with the latest techniques.
  More Straw Bale Building is designed to fill this gap. A completely rewritten edition of the 20,000-copy best--selling original, it leads the potential builder through the entire process of building a bale structure, tackling all the practical issues: finding and choosing bales; developing sound building plans; roofing; electrical, plumbing, and heating systems; building code compliance; and special concerns for builders in northern climates.
• "Vapor Barriers or Vapor Diffusion Retarders", U.S. DOE: how vapor barriers work, types of vapor diffusion barriers, installing vapor barrier
• Ventilation for energy efficient buildings, Purpose, Strategies, etc.,