Following an ITN report on the continued clean-up efforts in Turkey, experts discuss the lessons learned from last week's earthquake.

MARGARET WARNER: Now, an update on the earthquake in Turkey and possible lessons for the United States. We start with a report by John Irvine of Independent Television News.

JOHN IRVINE: Communities living under canvas: This is a familiar sight across the earthquake zone. The 200,000 survivors have become refugees. Today we flew over the town of Yalova. Here like elsewhere, for every demolished building, there are dozens more partially collapsed. They will have to be pulled down. It will be a long time indeed before people take holidays again in this seaside resort. Poor weather has made living conditions even more arduous, but mercifully there's no sign of the epidemics that were feared. Fifty-thousand Turkish soldiers are now helping in the relief effort, but some victims of the quake are still critical of their own government.

They reserve praise, however, for other countries. "Aid has come from America, Israel and elsewhere. Even the Greeks have helped us," said this man. "It would be great if these new friendships could continue." The official death toll stands at 12,500, but three times that number of people are still missing. They are lost under rubble and under water. In some areas, the shoreline was reclaimed land, but now the sea has taken much of it back. Although the earthquake happened at 3 o'clock in the morning, it was a hot night, and the promenade here at Golcuk was still a busy place. That promenade is now gone. At least 150 people lost their lives here. As divers spent the day searching for bodies, expert surveyors deduced that this land was simply too vulnerable to build on.

MARCO MUCCIARELLI, Seismologist: Unfortunately, here people built it too close to the coastline for high seismicity region.

JOHN IRVINE: No longer do they work carefully through the rubble. This has become a clearance operation, and tragically that means many of the dead will stay lost in the wreckage.

MARGARET WARNER: Elizabeth Farnsworth in San Francisco takes the story from there.

ELIZABETH FARNSWORTH: What lessons should officials and builders in California and other earthquake-prone areas of the U.S. draw from the Turkish quake? The day after the Turkish disaster there was a small quake north of San Francisco, a reminder that millions of people live and work near the San Andreas Fault that runs down much of California.

We turn now to Maryann Phipps, a principal at Degenkolb Engineers, a structural engineering firm headquartered in San Francisco; Peter Yanev, president of E.Q.E. International, a risk management and structural engineering firm also based in San Francisco-- he is just back from Turkey; and Robert Wesson, a research geophysicist at the U.S. Geological Survey. Peter Yanev, describe the damage that you saw.

PETER YANEV, Structural Engineer: Well, let me go back a little bit because this is not the first time. I've sent teams to about 70 earthquakes now. I've personally gone to about 34, 35, including some of the century's worth events. And this is, in my opinion, the worst so far.

ELIZABETH FARNSWORTH: And continue. What did you see?

PETER YANEV: Well, it was destruction on a massive scale. Many, many hundreds, probably thousands-- I couldn't see them all-- buildings collapsed, many probably tens of thousands of buildings, damaged, most of them concrete, some of them of the type that we have in California, older buildings. The footage of some of the ground settlement, much of that was caused by faulting right in the vicinity of the buildings you just showed. There is quite a bit of faulting in the area that actually collapsed hundreds of buildings. This was a new experience for me. It was very much like the 1906 earthquake...

ELIZABETH FARNSWORTH: Can you explain that a little bit, faulting in the areas?

PETER YANEV: In 1906, the San Andreas Fault broke over a long distance a couple of hundred miles plus, where the western part of California slipped north with respect to the continental United States. In effect, the North Anatolian Fault that caused this earthquake did the same thing. Most of Turkey slipped ten, twelve feet towards Greece to the west. And where the actual faulting occurred, where the ground ruptured, were many hundreds of buildings right on top of the fault, and most of those collapsed almost instantly.

ELIZABETH FARNSWORTH: Mr. Yanev, I'm going to come back to you for some more specifics about the buildings. But first, Mr. Wesson, you've been studying the motion recordings posted on the Web from Turkey. What are you seeing? What have you learned? And what are they?

ROBERT WESSON, U.S. Geological Survey: Elizabeth, in California, in the western United States and in Turkey, strong motion accelographs are installed to measure the kind of strong shaking that we saw from this earthquake. So far, there are not quite ten strong motion recordings that have come to us from Turkey, and we see what we call accelerations-- that's one of the parameters that are measured with these instruments-- we see accelerations about one-third of a G, one-third of the acceleration due to gravity. These are accelerations that we would expect from an earthquake about this magnitude, and it's the kind of accelerations that buildings are designed for in California.

ELIZABETH FARNSWORTH: And Mr. Yanev, what did you learn about the structural damage specifically from your trip?

PETER YANEV: We were able to take a look at a wide variety of structures, from industrial to residential to commercial buildings. The primary reason for the massive failures is inadequate structural design of the buildings. Typically in Turkey they build using concrete. They make these relatively simple concrete frame buildings, and then in-fill between the frames where the windows and the doors are with unreinforced masonry. It is popular construction in much of the world. It's used in other areas of the U.S. where we have no earthquakes.

ELIZABETH FARNSWORTH: Okay now, I'm going to interrupt you right here because we've got some visual aids here in San Francisco to understand this and then I'll come back to you. Maryann Phipps, explain this more, the rebar you've got for us.

MARYANN PHIPPS, Structural Engineer: Well, what we need to have buildings remain safe in an earthquake is we need strength and we need toughness. And when we talk about reinforced concrete construction, the toughness comes from the reinforcing steel, or rebar as it's called. So this is a piece of rebar like we would see in any construction site in the United States, similar to what was in the Turkish buildings, but in many ways very, very different. In the buildings in Turkey, the reinforcing steel was mostly smooth bars, not deformed like these are, so they didn't catch on and connect to the concrete as well. And it wasn't wrapped with other reinforcing steel to make it tough and to give it some...

ELIZABETH FARNSWORTH: Okay. We have a picture actually here. Explain what we're seeing in this picture.

MARYANN PHIPPS: What we're seeing in the picture is long reinforcement without much confining reinforcement around it, and so what happens is the concrete inside of it basically, once it cracks, is no longer able to withstand any load, so it just becomes rubble and leads to the collapse. In contrast, what we need is this closely-spaced reinforcement, these hoops or ties.

ELIZABETH FARNSWORTH: We've got a picture of that, too. And this is what you'd see in the United States.

MARYANN PHIPPS: That's what we'd see in virtually any earthquake-prone areas in the United States in a concrete frame type construction. And it's those bars, those extra bars that give the building some level of toughness, the ability to kind of hang tough and hang together and withstand or ride out a long earthquake.

PETER YANEV: Yes.

ELIZABETH FARNSWORTH: Did they survive?

PETER YANEV: Well, it is difficult to judge by quickly looking at the building without the plans, but what was obvious that you would have a collapse right next to it a building that was intact, near it a building that had no damage then several collapsed buildings. So obviously, there were great differences in the quality of the construction, the quality of the design. Now, what Maryann said is exactly right. In Turkey, the situation is a bit different. In the United States, in California certainly, we have very strict inspection of the engineering design for different buildings. That is not the case in Turkey. So the engineer may have actually designed the building to have all these reinforcing details that we showed, but if they're not built in the field because nobody is inspecting and the contractor does what he wants, you run into problems. In Yalova, which you talked about earlier, one contractor apparently designed somewhere around 60 buildings, all but two of them collapsed in the earthquake. These are all buildings done in the last five years. So it's not just the design; it's the quality of the construction. In fact, the Turkish code is identical for practical purposes to the California code. The application, however, is very different for the common buildings. We saw very high quality in some of the industrial buildings, comparable to what we have here.

ELIZABETH FARNSWORTH: All right. Let's get into the lessons now, beginning with you, Mr. Wesson. What lessons, judging from everything you've learned, do you draw for those of us in San Francisco, for example, or other earthquake-prone areas?

ROBERT WESSON: The principal lesson, Elizabeth, is that we have to remain vigilant. There was an earthquake along this same section of the fault just over 100 years ago. So 100 years seems like a long time to those of us who are trying to pay our mortgage or worry about groceries for the next day, but when we're worried about earthquake issues, we have to really take a very long view. Secondly, there are many lessons ... this is such a tragic earthquake, but there are many cities around the world, not in California, but in the developing world, where we have the same problems that we have in Turkey, and this truly unfortunate disaster could happen in many other places. Thirdly, as I think my engineering colleagues will discuss, there are buildings in California, in the seismically active parts of the United States, that are not built to the current codes and could represent serious problems in the event of an earthquake.

ELIZABETH FARNSWORTH: Maryann Phipps, talks about those buildings. And would there be a loss of life similar to Turkey if an earthquake like that occurred here?

MARYANN PHIPPS: Well, if we have a similar earthquake, we are definitely going to see a lot of damage in our buildings. We will not, however, see the some kind of loss of life, and that's because many of the buildings that we've constructed over the past 30 years are likely to protect the life safety of the building occupants and those nearby in an earthquake. Our codes, our enforcement of the codes and the quality of construction will give us a much higher level of protection in that new construction. But it's correct that we have lots of older buildings, too. We have a large building inventory, many of them built over the past century, and several of those buildings will in fact be collapse hazards, partial collapse hazards in an earthquake of the type we saw in Turkey.

ELIZABETH FARNSWORTH: What do you recommend be done with those buildings?

MARYANN PHIPPS: Well, we need to be vigilant about moving forward and preparing ourselves by retrofitting them, by phasing them out over time. You know, in California for example, with our hospitals, we have a program that by 2008, we will have strengthened or taken out of commission any hospitals that pose a safety hazard in an earthquake. We need to take that same kind of precaution, those some kind of steps for other classes, other types of buildings that we know are vulnerable in earthquakes.

PETER YANEV: Well, there are many. I'll try and hit two or three of the best ones. We've done one thing very well in California. Dr. Wesson's colleagues, the geologists, have done a wonderful job of delineating many of the active faults in California. We have laws where we cannot build on top of the faults. One of the major problems from this earthquake as I said, were collapses of hundreds of six-, seven-, eight-story buildings that were on top of the fault that ruptured. We also have much stricter code enforcement here in California. I think that leaves something to be desired in other parts of the country. For example, the areas around St. Louis, around Salt Lake City, around Seattle, I think need to have a bit stronger construction than they are currently using. That will take a long time to explain, but effectively their construction, because of lower probability of earthquakes is weaker than what we use in California where we have more frequent earthquakes. However, when large earthquakes occurred, whether it's Salt Lake or it is Seattle or it is San Francisco, the damage can be spectacular. The higher the design, the lower the damage. We also saw some very, very good performance of well-designed modern structures in Turkey. That is encouraging.

ELIZABETH FARNSWORTH: And Mr. Yanev, you saw the refinery that burned.

PETER YANEV: Yes.

ELIZABETH FARNSWORTH: What did you learn about oil refineries near faults -- which are there are many of them here in the Bay area and in LA.

PETER YANEV: That's right. Thank you for reminding me about that. That refinery probably has suffered a loss of $1 billion. Right now, the estimate for the whole earthquake covers around $25 billion. That may be a very preliminary number. It may be much higher. It may be somewhat lower. So one industrial site accounts for 4 percent of the total loss of property, not lives. There were no lives lost, as far as I know, in the immediate vicinity there. The refinery is not that different from many refineries around the world. More so if you look around Tokyo Bay, where there is a very high density of refineries, many of them built to much lower standards than what we saw in Turkey -- we are looking there at a human and environmental disaster waiting to happen. There are many companies around the world that need to take the lesson of Turkey at heart. Industrial buildings in general have another problem and that is business interruption. Without these buildings, factories cannot work. For example, Silicon Valley in the Bay area, in a major earthquake, many of the fabs on which we depend to manufacture the silicon chips would not be functional for months afterwards?

ELIZABETH FARNSWORTH: I'm sorry. Many of the "what" would not be functional?

PETER YANEV: Of what we call the fabs, the fabricating plants that manufacture the chips -

ELIZABETH FARNSWORTH: Oh, right.

PETER YANEV: -- silicon chips that go in all this sophisticated modern equipment, electronic equipment. We expect that a similar earthquake such as the one in Turkey, in Japan, in California, in Taiwan, in other areas with high-tech industry, would cause business interruption - in other words, shutting down of major industrial facilities for as much as eight months. This is probably what will happen with the refinery. And this produces about a third of the oil of Turkey. They've got another problem on top of the obvious problem of life loss and building loss.

ELIZABETH FARNSWORTH: Mr. Wesson in the short amount of time we have, they're putting sensors in that fault like they are faults here. Any chance that they'll be able to foresee another quake?

ROBERT WESSON: Elizabeth, we're not very... we can't predict earthquakes in the short term. We can make some probabilistic statements about the long-term probabilities, statements like those were made for this part of the North Anatolian Fault, but we're not able to make short-term predictions. What we can learn from sensors is about the character of the faulting and about the character of the ground motion that affects these buildings.

ELIZABETH FARNSWORTH: All right, well, thank you all very much for being with us.