Palos Verdes - Portuguese Bend - Getting Worse

[jar546]

There are many news stories that just came out because of recent developments. Here is some history on this area of southern California, south of Los Angeles.

Portuguese Bend Landslide: Ongoing Challenges and Recent Developments​

Introduction​

The Portuguese Bend area in Palos Verdes, California, has a long history of geological instability. Recent news highlights worsening landslides in this region, leading to significant disruptions, including power cuts to approximately 140 homes. This article provides an overview of the history, current issues, and implications for building safety and code enforcement in such geologically sensitive areas.

Historical Context​

The Portuguese Bend area has been geologically unstable for millennia, with its first major landslide recorded in 1956. This landslide was triggered by a combination of natural factors and human activities, particularly the construction and grading that disturbed the fragile geological composition of the area. The land here is primarily composed of ancient landslide materials and marine sediments, which make it inherently prone to movement.

Recent Developments​

In recent years, the situation has worsened due to increased rainfall and possibly other environmental factors. As of September 2024, worsening landslides have led to power being cut to around 140 homes in the Portuguese Bend area. This precautionary measure was taken to prevent further damage and ensure the safety of residents. The ongoing land movement continues to pose significant risks to structures, utilities, and residents.

Building Code Implications​

For building code officials and developers, the situation in Portuguese Bend serves as a crucial case study. It underscores the importance of comprehensive geotechnical assessments before any development in areas with known geological risks. Building codes in California have evolved to include stricter regulations for construction in landslide-prone areas, including requirements for detailed site analysis, drainage control measures, and the use of flexible infrastructure that can accommodate land movement.

However, as the situation in Portuguese Bend illustrates, even the most stringent building codes may not fully mitigate the risks in such unstable areas. It highlights the ongoing need for regular monitoring, maintenance, and possibly even reevaluation of existing structures to ensure they remain safe as environmental conditions change.

Conclusion​

The Portuguese Bend landslide is a stark reminder of the challenges posed by building in geologically unstable areas. It also underscores the need for robust building codes and constant vigilance from building officials and residents alike. As the situation evolves, it will be essential for all stakeholders to stay informed and proactive in addressing the ongoing risks.

 

[jar546]

More info 2024:

 

[jar546]

Displacement direction:

 

[jar546]

GPS Monitoring 2024 (movement dates on map)

 

[Yankee Chronicler]

My opinions on this are influenced (some might say "tainted") by my background as an architect. In addition to my home state license, I also held an architectural license from California for many years -- roughly twenty. Even though I had passed the national NCARB licensing exam on my first try with flying colors, when I applied for a California license (with NCARB certification), I had to travel all the way to California to undergo an oral interview and an exam in seismic. California has always been at war with the NCARB and with the code-writing organizations, maintaining that California is so unique and so special that they should be allowed to make their own rules and regulations, and that they should be exempt from any rules and regulations they don't like.

That's a harsh way of stating it and I admit it's a bit of an overstatement ... but not much of one. The California architectural licensing board publishes a periodical newsletter (quarterly, if I remember correctly), and such issues were often discussed in the newsletter. If you were to listen only to the California architectural licensing board, you would think that California is the only state that has rain, California is the only state that has snow, California is the only state that has wind, and (of course) California is the only state that has ever had an earthquake. In other words, their poop is odorless.

Yet, any time I see a headline about a subdivision being wiped out in a mudslide, I don't even have to read the article to know that it happened in California.

Let's face it -- it shouldn't happen, yet in California it happens with alarming frequency. Obviously, something is wrong. The question is, what is wrong? Where is it wrong? Is the problem that the building codes aren't strict enough regarding geotechnical issues? Probably not -- the codes require geotechnical analyses.

Is the problem that the codes aren't being properly enforced? That's a possibility, and it's one that probably none of us can address because it can vary widely by jurisdiction. I know that in my current position when I ask for "the required" geotechnical report for new construction, more often than not all I get is pushback. This has happened twice in the past couple of months with projects that are situated on land adjacent to a river, one almost entirely within a 100-year flood plain and the other with the proposed building half within the 100-year flood zone and half not. That's a guaranteed recipe for differential settlement if not handled properly.

So some of the issue may be that building departments aren't requiring geotechnical reports ... or that they aren't ensuring that the designs follow the recommendations in the geotechnical reports. And that's a very real possibility, because most building departments don't have the time to read a multi-page report that may use obtuse, opaque technical language.

And, of course, the third prong is that the "science" of geotechnical engineering may not be up to snuff. My state many years ago began requiring that structural designs for what we call "threshold" buildings (occupant load greater than 1,000 people; height more than three stories or more than 60 feet in height; clear spans more than 150 feet; total building area more than 150,000 s.f.; and a few more) to have the structural design checked by a second, unaffiliated structural engineer. Maybe California needs to have geotech reports subjected to similar peer review.

I don't have an answer. I do know this is not the first time structures have been lost or endangered due to mudslides in California.

 

[jar546]

Here is an interesting video. Landslides are not limited to California. It can be anywhere that has relatively steep hills or mountains.