Perhaps the most notable of these pre-Commission civic group victories were the salvation of the Carnegie Hall (William B. Tuthill, 1891) in 1956 and the Dakota Apartments (Henry J. Hardenbergh, 1882) in 1961 (landmarked in 1970). Although it must be noted that the Carnegie Hall survived the replacement by a 44-storey gold-coloured high-rise slab (Pomerance & Breines) mostly because of the developer's funding problems...

After decades of "vintage" building replacements, the last straw was the tearing down of the old Pennsylvania Station (McKim, Mead & White, 1910) (link) in 1963-1966 and the Renaissance château of the Brokaw family at Fifth Ave./E 79th St. in 1965, when the New York Landmarks Preservation Commission was formed and the Landmark Preservation Law passed to prevent the destruction of old buildings of historic significance. (The architect firm of I. M. Pei, which was involved in a replacement plan for the Penn Station, a 32-storey giant mart called the Palace of Progress, the world's largest building, had in 1956 also made a proposition for another NYC preservation hot potato, the Grand Central tower. The Grand Central development proposition, by the way, led to the compiling of a list of New York City's historic buildings by the Municipal Art Society. In 1957 the list of buildings recommended for protection from further development was published -- along with a disclaimer that the Society does not take responsibility for the listed properties losing their resale value...)

The commission consists of eleven commissioners, selected by the mayor and serving for three years, helped by staff personnel and volunteers. The appearances of buildings (or their selected portions, like interiors) with a granted landmark status are controlled by the commission, so that any requested changes by the owner are subject to Commission's review.

Demolition of a landmark is prohibited, unless the owner can present financial reasons for it -- even then the city will first try to find a more co-operative buyer for the building, offer tax abatements, or enable the selling of property's air rights. The landmark status also requires the owner to keep the property in good shape and safe to operate. In return for these demands, the owner will be presented tax abatements and advantageous loan arrangements, as well as other benefits.

(Even the designated status is not always enough to prevent the owners from demolishing parts of a landmark. In 2002, the Amster Yard, a grouping of 1966 landmarked buildings around a landscaped courtyard on 49th Street at Second Avenue, was mostly demolished without a review or acceptance from the Commission. In lieu of the approved renovation of the existing buildings, most of the buildings as well as the whole courtyard were demolished and dug up from the way of an underground auditorium and educational facilities within the rebuilt replica houses. Although the regulations allow the city to fine the owner up to the whole value of a destroyed landmark, it is uncertain under what circumstances such measures would be taken.)

Five years after its forming, the commission, still uncertain about its power against the investors and large companies, failed to prevent the demolition of the Singer Building from the way of new office space construction. The commission, however, had gradually increased its power through media management and gaining of political support for its aims. Now the commission has consolidated its authority and has also spread its influence into preserving important public interiors, the interior of the Public Library being the first one in 1973.

Despite its increased influence and power, the Commission has been at times surprisingly slow in enforcing a landmark status on, at least in the Great Public's eyes, notable structures. Although a landmark must be at least 30 years old, the designation has often taken considerably longer. The Chrysler Building (landmarked in 1978), Empire State Building (1981) and the Rockefeller Center (1985) have been such high-rise examples.

In addition to the individual and interior landmarking, the Commission also designates so-called Historic Districts in which a specified area ranging from a few buildings to whole neighbourhoods (like Greenwich Village) is declared a landmark, with similar effects on property owners. The designation, and subsequently a "forced-on" orientation to preservation has stimulated renovation of these old, previously overlooked buildings.

Another large-scale designation type is the Scenic Landmark designation, in which an area of scenic and natural importance is preserved from changes. Central Park is the most notable, or at least the largest, of these.

As of May 1997, after 32 operating years of the Commission, there were 964 individual landmarks, 98 interior landmarks, 69 historic districts and 9 scenic landmarks, mostly in Manhattan.

The use of modern multimedia PCs and increased amount of data within in-building networks required new horizontal distribution for the telecom cabling. Also, according to old cabling standards each type of cabling had to use a separate routing, whereas the new cabling could be placed together in a common infrastructure. In addition to data communication, every office has also extensive facilities for plugging-in of audio-visual appliances.

As the AT&T Building was not built as an open office environment, unlike most modern office buildings, but rather as one consisting of office rooms with walls between, the distribution of the extensive cabling was possible to make as a fixed infrastructure within the cellular floors to the fixed walls -- there was no need to take into account possible changes in the furniture layout, unlike in the open offices. The telecom facilities were, all in all, expanded to fit the needs of the planned 1,600 Sony employees, as opposed to the 600 AT&T employees.

In addition to the telecom systems, also the HVAC (heating, ventilation, air-conditioning) systems had to be uprated. Sony wanted to increase the amount of rejected heat within the building by a quarter. The pediments on the roof of the building, where the cooling towers were situated, had the effect of circulating some of the emitted steam back to the towers, thus degrading their designed performance. By modifying the towers the cooling effect was increased by 17 per cent. Also the chillers in the building had been working under their rated capacity, but after a complete overhaul their capacity was increased by 25 per cent. By adjusting these installations, instead of a complete replacement, $1.5 million was saved.

Yet another area where the existing systems in the building were less than satisfactory was the air-conditioning system, more precisely the ductwork effectiveness. The needed air-conditioning volumes couldn't be reached without either modifying the existing ductwork or by uprating the fan systems. As there was concern about compromising the original Philip Johnson-designed ceilings, the fan system was uprated instead. The procedure brought additional costs of $3.5 million.

The lighting fittings were modified to suit the kind of work that the employees performed. The existing core fluorescent lighting used as ambient lightning around the building's circulation core and at the perimeter windows was retained, but the individual work lighting was made either as furniture-mounted lighting or as swing-arm lamps with their own switch, depending on the nature of the work and the office space. Additional lighting was also installed to specialty areas of the building.

The most visible change for the general public was the conversion of the existing open-space arcade at the back of the building into the enclosed Sony Plaza with its retail spaces and street-like plaza with cafés, trees and street lights. As a showcase for Sony's newest products,the plaza was designed with theatrical lighting, which in turn required an effective cooling system. As the cooling capacity of the whole building was already at its limits, a separate chiller unit was added for the plaza use. The snow-melting installation under the floor was retained, this time to warm the tile-covered floor of the plaza.

There are a number of reasons behind the growth in renovation. An office building of the 1930s and 1940s may have typically small floors, especially in the tower portion, and be unsuitable for installation of modern office building services, thus making residential conversion attractive. The office buildings from the 1950s and 1960s do generally have larger floors, but they also would need extensive refitting in order to house all the modern communication installations. Buildings of this era were also built with liberal amounts of asbestos inside, thus making a proper renovation and conversion feasible. Reductions in taxation for renovated premises also attract owners to "go the renovation way"; replacing an older building is no longer as economically viable a solution and less likely to return the investment, as opposed to renovating old premises. In fact, because of recent reductions in allowed building volume to a plot, the existing building can well have a larger internal volume than the new one would.

The increase in renovation can be traced back to the 1980 city law that required regular inspections and maintenance of buildings over six storeys. The utilization of tax incentives introduced in 1990 for the Wall Street area renovation and conversion, along with the financing difficulties of new projects during recession added to the popularity of renovation.

The diminished assignments on new projects forced also designers to specialize in renovation rather than merely concentrate on new construction. Luckily for them, the image of the older buildings also often attracts tenants, both firms and private persons, more than the interiors of the post-war International Style buildings. At the same time, also the Modernist office buildings are renovated and converted to other uses, like dwelling, which in some cases also requires strengthening of the frame as these high-rises are more prone to sway than the older ones with a more rigid internal frame.

Although parts of Downtown were rezoned by the city to allow conversion into residential areas, the expected pace of office building conversion, especially for the older buildings, was somewhat reduced due to the acute lack of office space in the late 1990s. The situation also led to increased rents throughout the city, and forced many companies to consider reducing their presence in the city or moving out altogether. As the vacancy rates started to increase again with the change of decade and the dot-com crash -- and finally with the attack on the neighbourhood in September 2001, which led to an exodus of commercial tenants and the spreading of companies' operations to multiple locations -- the change in demographics led to a renewed interest in apartment conversion, not least due to the introduction of state and federal financing programs.

Financial programs have been imperative in the current conversion boom: converting an office building into apartments is three to four times more expensive per sq.ft than renovating an office space. In September 2003, Cushman & Wakefield reported that there were 2,395 residential units underway, with 3,020 more in the planning stage. These were seen to be mainly rentals, due to the conditions of the federal financing.

Of the $8 billion in federal Liberty Bonds for 2002 onwards, $1.6 billion has been set aside for residential uses. In addition to the considerably lower interest rates for the loan, the bond program also allows certain NYC real estate taxes be delayed or avoided altogether. With the Liberty Bond program expiring at the end of 2004, there have been suggestions of redirecting some of the commercial portion to residential construction.

By September 2003, approx. $600 million in bonds had been approved by the city and the state; the bond program has, for example, provided $82 million for the conversion of a 27-storey building built for Bank of New York at 90 Washington Street into 398 apartment units (link).

Wall Street has increasingly become residential or been converted to hotel use and around City Hall and the WTC, the Woolworth Building is to have an all-residential top of 145 units, with a new rental tower nearby at 10 Barclay St..

In addition to a general shortage of apartments in Manhattan, an impetus for residential conversions has been the willingness of Wall Street professionals to pay well for a privilege of living near their workplaces. Approx. 35 percent of Lower Manhattan residents walk to work -- a more pleasing prospect than commuting every day in a crowded train or ferry.

Although the number of residential services like grocery shops and laundrettes is still modest in the previously all-office neighbourhood of Wall Street, the growing number of inhabitants is expected to lead to an increase in these too.

The rising prices of residences in 2005 have kept the conversions coming, with even such venerable NYC institutions as the St. Regis and Plaza hotels announcing plans of converting part of their guest rooms into apartments. After a change of hands, the ex-Metropolitan Life Insurance Co. Tower at 1 Madison Ave. will also face a residential makeover, albeit only on the inside, due to the national landmark status of the exterior. The relatively small floorplates of the tower are more suited for residential than office use, and the floors have, moreover, a higher than normal ceiling height, always a plus in high-price apartment marketing.

In March 2006, there are around 20 new conversions underway in the Financial District, totalling 560,000 m² and adding to the 650,000 m² already given the residential makeover (CB Richard Ellis). And with such re-born heavy-duty luxury addresses as the 23 Wall Street (renamed simply the "Downtown"), 20 Pine Street ("Collection by Armani/Casa" -- don't ask me) and the 55 Wall Street ("Cipriani Club Residences"), the Downtown conversions have turned the page on the first tentative and relatively bargain-level rental redevelopments of the 1990s.

Of the annual over 900,000 earthquakes worldwide, most are minor tremors well under magnitude of 2.5, with serious ones of 8.0 occurring only at 5 to 10 years' intervals. Although these generally occur in plate boundaries, the most severe earthquakes -- recorded ones, that is -- in the USA have actually occurred in intra-plate areas, areas within the plates themselves. The three record earthquakes in the USA all took place in New Madrid in Missouri between December 1811 and February 1812. They ranged in magnitude from 7.6 to 8.2. There were also no less than 203 damaging aftershocks.

Of these intra-plate earthquake areas, Charleston, South Carolina, eastern Massachusetts, the St. Lawrence River area and the central Mississippi River Valley are those mostly affected. Although southern California has 100-fold earthquake activity as compared to New York State, over 400 pinpointed earthquakes of over 2.0 magnitude have been nevertheless recorded in NY between 1730 and 1986. The state has been the third most seismically active of those east of Mississippi River.

Two notable earthquakes have occurred in New York City: the 5.0 magnitude tremors in 1737 and 1884, both originating from Rockaway in Queens. If the time between the earthquakes and the time since the last one are studied, the likelihood of the next occurrence is about 50 years away, although any specific possibilities are hard to come by due to the relative lack of earthquakes in the NY State. General estimates for a 5.0 M occurrence are about 200 years, 6.0, 600 years and 7.0, 2000 years. Of course any estimated likelihoods are just that, likelihoods, not necessarily having anything to do with the actual occurrences -- such earthquakes could occur also on following years, or months...

A "critical" earthquake in the New York City area has been estimated at the value of 5.8 M. But due to the circumstances in the city and the numerous shortcomings in its structures and preparations such an earthquake would have an effect closer to the 7.0 M that occurred in 1995 in Kobe, Japan. The estimated maximum for an intra-plate earthquake is about 8.0, the size of the New Madrid earthquakes. The situation and expectations are not helped by the fact that about 80 per cent of the nation's earthquake-hazard prevention budget is spent in California and Alaska, with preciously little reserved for other parts like New York City.

Although the reasons for intra-plate earthquakes are somewhat a mystery, one reason for the seismically relatively active conditions in parts of the East Coast can be traced to the time when the African continent was joined with North America. On the separation, approx. 200 million years ago, it left behind a formation, Cameron's Line, that runs through New York City roughly along the East River, to Staten Island and beyond. The corresponding parts in Africa and North America share not only similar geological formations like brownstone and red sandstone, but also the ability to produce earthquakes of up to 7.5 M. In addition, the relatively cooler underground temperatures in intra-plate areas, when compared to California, have an additional effect of increasing the area that an earthquake affects. Because earthquake tremors travel more effectively through cooler rock, a strong earthquake even quite some distance away from NYC could hurt the city -- an earthquake in Charleston in 1886 cracked walls in Harlem and was felt all the way in Omaha.
(See also: commentary)

As for the subsoil conditions in NYC itself, the well-known Manhattan bedrock rises to the surface in the northern part of the island, extending also to the north. The bedrock falls deeper as we go to the south and east, forming still a reachable foundation for buildings in Midtown, but generally not as far south as in Downtown. Because bedrock forms a solid base for a building, it, despite also transmitting seismic shockwaves effectively, will be a better choice than soft soil. The ample soft soil in New York would be the cause for the city's major harm in case of an earthquake. Not only does it amplify the seismic waves and direct them to the surface, but parts of the city land are also prone to so-called liquefaction, an abrupt loss of soil cohesion. The sand particles lose their friction resistance under the earthquake vibration and get mixed up with water beneath the ground surface, naturally losing any support it gives to a structure. A particularly clear example of its effect was the accident in Brooklyn, where building a sewer in reclaimed land with a vibratory pile driver collapsed four houses within two blocks with the loss of a life. The agitated soil had given way even from that distance and led to the collapse. Much of the waterfront is filled-in and reclaimed from the rivers with soil that is prone to liquefaction, especially below water level. The most notable of these landfills is the Battery Park City in Downtown Manhattan, which would face severe problems in a major earthquake -- as would do many other vital services, like several major hospitals or the Long Island airports on fills, with JFK also near Rockaway.

The structural frames of buildings differ also in their resistance to earthquake tremors -- a steel-framed high-rise building, maybe surprisingly, being the (relatively) safest. The ones to avoid in NYC would be its numerous brownstones and "walk-ups", masonry and brick-built, un-reinforced 19th Century houses -- in addition to a literal risk of total collapse (or partial, of floors, stairs or elevators), they and other apartment buildings could also shower(!) the streets with decor sculpturing and air conditioners. The old buildings housing the city's fire companies also could have problems like jammed doors due to collapses, making a dash out a bit problematic... Similarly, also collapses of schools and armouries, of masonry and concrete, could set recovery back because these are designated as victim housing centers.

The subway might be a better bet than streets or building interiors. As well as effective bomb-shelters, the deep-dug stations of the "tube-built" systems in many cities would also survive better in an earthquake. Although the MTA subway is a dug-in shallow system closer to the danger zone in the surface, the stations may perform well enough as shelters, even with some sinking that occurred in Kobe. The NJ-NYC PATH tunnels are no place to be during an earthquake, as the old cast-iron tunnels are likely to be destroyed.

As well as threatening the subway system, earthquakes will also almost certainly sever the services running between street-level and subway tunnels. Water, rain and rainwater sewers, electricity, gas, phone cables all are prone to get severed in tremors, causing truly a disaster in the city. As much of the pipeline network for these services is old, pipes of wood and cast-iron, it is going to suffer severely. Also the two fresh water tunnels from upstate supplying nearly all the water to NYC are old and vulnerable to an upstate earthquake (they actually cross a fault line), which could sever both and leave the city almost without pipe water supply.

In a situation of fires raging within the city as a result of an earthquake -- it has been estimated that one would cause over 130 separate fires -- the loss of water supply or water pressure is simply unbearable. Add to that split gas pipes, loss of electricity and lighting and streets filled with abandoned cars -- as well as destroyed airport runways, bridges and tunnels -- and crime-fighting, firefighting, rubble removal, rescue and medical operations will be facing a severe uphill battle. With the need to get key groups into the now-isolated Manhattan -- like the large amount of policemen in Manhattan precincts living outside the island or the nationwide rescue teams or the Guard -- and the fleeing people out, the task isn't made any easier. The rule of "golden 24 hours" (which gives a 93% survival rate for people rescued in that time) would require swift actions -- delay it to 72 hours and 95% of the victims are dead. Even in the best of transport successes, the amount of destruction may well overwhelm the resources of even a large number of -- professional or ad-hoc -- rescue teams.

You really don't need a flying saucer flattening The City in a Hollywood blockbuster, in worst case the nature could almost provide such.

The method of searching for hitherto concealed fault lines is one means of trying to locate potential new earthquakes. By searching for natural marks from aerial photos that would indicate water or natural gas seeping to the surface through the fault lines, these lines may be located. So, lines formed by simple streams, dead or dying plants or autumn brown-coloured trees on an aerial photo can be an evidence of such lines. So far, only a few earthquakes have been able to be connected to the found fault lines' location, largely due to the inaccurate determination of an earthquake's origin point and the great depth (up, or rather, down, to 20 kilometers) whence they occur.

The New York City Seismic Code, which came into effect in February 1996, determines the conditions, design parameters and requirements for earthquake-resistant design and construction of buildings and their affixed components as well as independently standing structures.

New York City is located in an area with a seismic zone factor of Z=0.15, making it a city with a moderate earthquake risk. The east coast earthquakes characteristically release high-frequency energy tremors that travel long distances in the relatively unbroken bedrock present in the eastern USA.

The ground underneath the foundations of a building is divided into five classes of rock and soil, from S₀ (rock) to S₄ (soft soil), with the type present being determined by testing. Similarly, the susceptibility for liquefaction will have to be determined for the softer soil types in the presence of water.

The site coefficients given for each of these rock/soil classes reflect their respective susceptibility for ground motion; there is a 3.5-fold difference between the S₀ value of 0.67 and the S₄ value of 2.5, effectively providing notably more lenient seismic requirements for buildings built on bedrock. The code does not even try to counter the effects of a maximum earthquake possible in the area with the frames' elasticity, the tradeoff in such an occurrence being acceptable damage through designed redundancy in the frame, as long as the building can be evacuated safely.

The additional costs of strengthening a structural frame against seismic forces range from a few percent to over 10 percent of the total structural costs, depending on the type of frame, type of lateral strengthening, number of floors, setbacks, rock/soil type etc. The strengthening against seismic forces can also prevent much of the damage done by possible terrorist bomb attacks (up to 80 percent of the structural failures in the support of the main facade and the slabs in the Oklahoma City Federal Bldg. could have been prevented with a modern earthquake-resistant frame design).

In addition to new construction, the code also regulates alterations and expansions to older structures. New expansions with foundations require these as earthquake-resistant and non-founded expansions valued at at least 60 percent of the existing building require strengthening of the whole structure. The older, masonry-framed buildings are particularly vulnerable to earthquakes, and are thus a special target for strengthening of the frame. As one way of countering the danger from adjacent buildings, the code requires a gap of 1 cm for every 6 meters of building height, meant to prevent the buildings from hitting each other during earthquakes (an example is the expansion of the Bush Tower). The distance as a function of height is for protecting the usually-sturdy high-rises against the pounding by probably less engineered low-rises, rather than the other way around.

Through extensive computer modelling, the approximate effect of an earthquake can be "predicted". In a lengthy study, nearly 37,000 buildings in Manhattan were modelled through their characteristics and the applicable soil types, and a 6.0 M earthquake, centered near Rockaway Beach, was then unleashed. Although over 1,000 buildings were destroyed or suffered major damage -- predominantly in the Lower Manhattan/Villages area with the masonry buildings -- over 2/3 of the studied buildings remained undamaged. (Of the destroyed buildings, 106 were masonry buildings (also 871 damaged) and one had a steel frame (494 damaged); buildings with concrete (182 damaged) and wood frames (10 damaged) suffered no collapses.) The studies showed also considerable damage to both technical and lifesaving services -- especially below 14th Street -- as well as up to 250 dead or badly wounded.

Earthquakes In The Midwestern and Eastern United States??!! (with a Risk of Damage map of the USA)
What Are Earthquake Hazards?
What Should I Do Before, During, And After An Earthquake?