When is a site-specific PSHA worth the effort? The answer has less to do with project type and more to do with uncertainty. A site-specific hazard study is not simply a way to obtain a different spectrum—it is a way to better understand the assumptions, sources, site conditions, and uncertainties that control the seismic hazard. This article explores when that additional understanding can meaningfully influence engineering decisions.

If the USGS Multi-Period Response Spectrum (MPRS) has become so sophisticated, what does a site-specific PSHA actually do differently? This article explores the key ingredients of seismic hazard analysis, including source characterization, recurrence relationships, ground-motion models, logic trees, site conditions, and basin effects, and explains how site-specific studies differ from the national hazard model.

Since the adoption of MPRS in ASCE 7-22, I have occasionally heard the question: "Do we still need site-specific seismic hazard analyses?" It's a fair question. The modern USGS hazard model is more sophisticated than ever before, but it remains a national model. This article examines what MPRS improved, what limitations remain, and where site-specific studies continue to provide value.

Why Geology Made Italy the Most Diverse Wine Country on Earth I had to ask about my home country -- Italy. I gave ChatGPT a long and too-detailed prompt, so it answered my questions more specifically. Had I not prompted it, we would have gotten a nice and general response. I am now happy I was specific in my prompt, so we got answer to the not-so-typical questions.... ME: okey one last blog, let's do this one about italy and wine. italy is my home country. also, there are so

This journey into learning about wines and earthquakes made me think of my beloved Argentina. I have family there. When I think of Argentina, I think of Buenos Aires as well as Las Pampas and it's high plains. So I had to ask: ME: let's start relatively fresh: Let's talk about Argentina. Not a seismic region at all. what makes its wines special? ChatGPT: "Great place to restart — and there’s a small (but important) correction first 🙂 👉 Argentina actually is a tectonic and

My journey into earthquakes and wine had one more stop... ME: So how do you explain France? They are not known for their earthquakes, but definitely for their wines.... ChatGPT: "Great question — and it actually reinforces the main point: 👉 It’s not frequent earthquakes that matter, it’s ancient tectonic history. France today is relatively quiet seismically, but its greatest wine regions sit on landscapes shaped by old mountain-building, faulting, and marine sediments that

In the age of ChatGPT, small talk turns into deep quests for me. Because I am Italian, people talk to me about either coffee or wine.... And that's how I went down an interesting conversation with ChatGPT that I wanted to share with you. I have seen the topic of "geology of wine" but we should actually go all the way to the source of the geology and look at "The Seismology of Wine" Here is a cut-and-paste of my conversation. ME: Why do the best wines come from regions that ha

Why Earthquake Design Allows Higher Collapse Risk (and Why That’s Okay) As you know, I am one of the proponents of a proposal that is...