Tehran’s old and dilapidated housing and building infrastructure in many districts of the province are in urgent need of renovation and retrofit. Particularly because the city lies on major seismic fault lines and the threat of an earthquake is always hanging like the Sword of Damocles. Tehran is well within the danger zone of an earthquake if not at the epicenter.
Recently a mild tremor in southern parts of Tehran went largely unnoticed; it was followed by a second 2.5 magnitude a week later in the more affluent districts of northern Tehran. Experts say these twin quakes occurred with a 20-year delay according to calculations for the cycle of earthquakes.
A report by ICANA - the Majlis official news website – warns that a major earthquake for Tehran is a real threat as studies have shown that the recurrence for earthquakes in the capital is every 173 years. The capital’s track record shows several tremblers have rattled the city and places in its vicinity. Twenty years ago a 4.5 magnitude quake hit a 33 km depth in Damavand, a potentially active volcano close to Tehran. Two years later Damavand was the epicenter of a Richter 4 magnitude quake at the same depth. And 21 years ago a 4.6 magnitude quake at 18 km depth was recorded in Garmsar, 95 km away. Eight years ago the same place registered a 4.1 magnitude quake.
Based on the existing seismological data, Tehran has so far been hit by over 1000 small and big earthquakes within a 100 kilometers radius around the city. The earthquakes registered measured between 0 and 5 on the Richter scale. The most frequent have been those measuring over 3.5. Based on this data, micro seismic activities have basically happened in the following areas: southeast of Tehran, south of Tehran, near south and north Rey faults, east end of Tehran, along Mosha-Fesham fault.
Fortunately, Tehran has not been hit by a severe earthquake in the last 150 years. According to the catalog of historical earthquakes and the existing documents, many earthquakes have hit the regions around Tehran, which might have affected the city. Seismological studies say the biggest earthquake so far hit the region (50 km off Tehran) in 958 AD. It measured 7.7 on the Richter scale. The quake was due to the activity of the western part of Mosha fault. The fault of the north of Tehran is situated between the western part of Mosha fault and the city of Tehran. If the north fault becomes active, the damages from the earthquakes will be more severe than those from the earthquake in the year 958. The north fault is situated between the urban areas and the northern mountain. It is more than 90 km long, but its northwest part is far from Tehran. Thus, its eastern part can potentially be the center of a future earthquake.
But a high-intensity quake now in the congested capital — where more than 10 million people live — would be a catastrophe. Unlike building codes in other endangered cities such as San Francisco and Tokyo, Tehran’s are relatively lax, and many residents live in unreinforced-concrete houses and the old-style buildings and outdated engineering technology used in the construction of many districts in the capital will turn into death traps in the event of a strong jolt. “The health ministry once estimated that a 7-magnitude quake would destroy 90% of the city’s hospitals. Tehran is so threatened that there has been periodic talk about moving the capital,” according to a 2009 report in Time magazine.
Old Buildings
Mehdi Hashemi an MP from Tehran, says more than 25% of the buildings in the metropolitan area of Tehran are not safe in the face of a probable earthquake.
“Dilapidated housing and office buildings pose a serious danger for the capital and it is the responsibility of the government to intervene by providing loans and other facilities to retrofit theses structures or replace them with new ones” says Hashemi, who is the speaker of the Majlis Civil Affairs Committee.
Most of the unsafe buildings are located in southern and downtown areas; therefore special attention should be given to these areas by urban planners and officials. With the prospects of damages being catastrophic, the snail pace at which the retrofits of old buildings are progressing is an indication that concrete measures are yet to be taken.
Mansour Arami is another lawmaker who is especially critical of the negligence of authorities towards old buildings.
“I think the government needs to pull out of construction projects altogether and instead pave the way for the private sector to handle the job of renovating old buildings or constructing new ones and monitor their work strictly.”
Lawmaker Fatemeh Alia also laments that it’s not just the old buildings but there are major safety lapses in the new constructions too. Since the fault lines of Tehran are laid out on the map, she says construction near these areas and on heights or foothills must be banned because they only exacerbate the already destructive damages from earthquakes.
NDMO Inept
Any talk about earthquakes, and the buzzword is ‘crisis management’. In fact an organization was created in the wake of the 2003 Bam Earthquake to address the same issue. National Disaster Management Organization of Iran (NDMO) is still operating, although it has not been given a permanent status yet.
Mehdi Hashemi chairman of the assembly of Tehran MPs is skeptical about the efficiency of this state organization meant to shore up defenses against natural disasters. “Unfortunately there is not enough preparation to cope with this threat and the NDMO has failed to meet the expectations of the Majlis.”
He says although a handsome budget has been allocated to the cause, disaster management has not delivered to parliamentary expectations.
Alireza Khosravi a member of the Majlis Civil Affairs Committee on the other hand believes that every organization should be judged based on its capabilities and limits and “NDMO’s performance has been satisfactory considering the resources that it has.” Nevertheless it needs to pay more attention to Tehran, he said.
Fire Threats
Of all the dangers from an earthquake in Tehran, fire is the number one concern. An earthquake can break natural gas mains and water mains, not only causing blazes everywhere, but making it difficult for the fire department in fighting the fires. Experts say these metal mains are only as strong as they are held by the walls and structure on which they stand and in case of an earthquake their weight can also cause further destruction.
Furthermore, natural gas exposure from broken mains can easily kill people trapped inside buildings, leaving no time for them to make an escape.This is where the automatic gas shut off valves comes to help should the threat of a gas fire or explosion caused by a broken or disconnected gas line becomes real, cautions Fatemeh Alia.
Lawmaker Hossein Tala, says the great volume of gas mains installed by the department of public utilities will cause problems if an earthquake strikes and warns about the vulnerability of water mains too. “The fact is much work has been done by public utility departments in recent years but unfortunately we are still struggling in infrastructure, management and resources.”
While the lessons of the destructive quake that ruined Bam eleven years ago are still haunting the nation, the question is whether there is enough will and foresight to avert a tragedy which could occur on a more massive scale in Tehran.
