Category Archives: Incidents

This morning the Corps of Engineer’s was finally overwhelmed and lost control of the flow rates out of Addicks and Barker Dams, losing the last controls over theBuffalo Bayou water level as it flows through the middle of downtown Houston. Dams are the most useful and also the most dangerous infrastructure in any community, and losing control of the outflow rate represents a significant escalation in the flood severity. Flood level management is an intricate dance of competing compromises, where retaining water behind the dam makes flooding worse upstream and releasing water makes things more severe downstream. The US Army Corps of Engineers does an excellent job navigating these difficult choices, and the disaster is always worse when the Corps loses their ability to influence the drainage patterns. Hopefully the impacted areas downstream have already been evacuated, and the rising waters spread slowly enough that first responders can help people out of harms way.

The focus of the regional emergency response system is, quite correctly, on assuring people’s safety and well being. Our work at Atlas includes participating in emergency planning efforts and also incident recovery efforts, but the actual emergency management is not part of our core expertise. For now we watch and wait, and hope that the available resources and management are enough to protect the people who are in harms way.

There’s a possibility that engineers at Atlas may assist with damage assessment and field-engineered repairs at flooded petroleum facilities along the Gulf coast. Until the flooding abates, though, there’s little that we can do besides monitor the situation and make plans for a rapid and efficient deployment. When the rain stops and the waters recede, that’s when it’ll be time for the engineers to go to work restoring safe conditions at dams, highways and bridges, industrial facilities, and other essential elements that make Houston a thriving metropolis.

TJ Earthquake Damage

Typical Damage at Trader Joes

Friday night’s earthquake in La Habra was interesting for a couple of reasons.

It was small, by California standards, at only Magnitude 5.1.  In fact, I have my automatic notification program set to M6.0 or larger because there are so many small earthquakes like this and generally they don’t cause any damage. I found out about this one through Facebook. So I guess yes, there’s at least one good use for Facebook.

Secondly, the shaking was surprisingly strong for an earthquake of this size.  The rupture was shallow, only 1.7 km deep, and the lack of attenuation up to the surface resulted in  peak ground accelerations as high as 0.25g.  I pasted the USGS shake map below with a handy key to the Mercalli Intensity Scale system of classifying earthquakes.

No serious structural damage occurred, though La Habra Utilities is reporting broken water and gas pipes. The lack of damage and injury speaks more to LA’s excellent building codes and earthquake preparedness than it does to the modest earthquake size. In other parts of the world, places that lack the resources, knowledge, and political will of metropolitan Los Angeles, these types of earthquakes cause fatalities. Intensity VII shaking in California knocks over a stack of wine bottles in Trader Joes. The same level of shaking in rural Afghanistan dislodges roofing stones from their timber supports and buries whole populations in their huts.

Small, generally consequence-free events like these are an opportunity for all of us to reconsider our knee-jerk reactions to troublesome regulations and building codes, a chance for us to give genuine thanks to the smart engineers who led the transition from unreinforced masonry buildings like San Francisco had in 1906 to the well built structures that now protect us from preventable misfortune. Here’s my list of earthquake heroes:

Harry Seed – Pioneer geotechncial engineer and shining light of inspiration

John Lysmer – Smartest good-humored numerical modeler

Vitelmo Bertero – Structural engineer, deep thinker, curmudgeon

CB Crouse – Towering intellect, practical seismologist, mentor

Steve Dickenson – Good friend, collaborator, and insightful earthquake engineer

Yumei Wang – Classmate and dedicated earthquake safety advocate

Jason Brown – Cheerful building code enforcer

Because of their work and the work of countless others, your home and office, your kid’s schools, the bridges that you cross, the port that handles your cargo are all safe from damage in these types of events.

Here’s the link to the USGS event summary, for those of you with interest:

Be safe, everyone.

La Habra Shake Map