Karachi Earthquake BiographySource (google.com.pk )
On the other hand, in contrast to Los Angeles, Karachi has experienced no damaging earthquakes in the past 150 years and few events large enough to be felt. The question currently faced by earthquake engineers is whether Karachi truly enjoys an aseismic setting or whether the absence of damaging earthquakes is only due to Karachi’s short and incomplete history.
A review of the known historical data on earthquakes within 500 km of the city shows that the historical record prior to 1800 is limited and unreliable. Having summarized what is known about tectonics in and around Karachi, it is clear that key questions still remain.
At best the hazard in Karachi might be low. At worst, however, the hazard in Karachi could be roughly comparable to that in Los Angeles, or perhaps even worse in Karachi given its proximity to the subduction zone, for which Los Angeles has no analog.
Considering the number of known active faults that menace Karachi from almost every direction, however, it seems possible if not probable that hazard is higher than that assigned by recent national and global hazard maps.
A review of historical seismicity near Karachi reveals that although it is within striking distance of one or more Mw 8 subduction zone events to the west, reverse faulting earthquakes with 6 < Mw > 8 in Kacchh region to the east, Mw < 7.9 strike ruptures to the northwest, and Mw 6 earthquakes near and possibly beneath the city, little or no data are available to characterise return times and probabilities for any of these events.
A consideration of relative seismic risk in Karachi and Los Angeles leads to even more alarming conclusions. Seismic building provisions, including the Field Act to protect public school buildings, were first adopted in California following the 1933 Long Beach earthquake.
Although Karachi adopted the Uniform Building Code (UBC) provisions for California in 1979, the code was never effectively enforced, a circumstance common to most of Pakistan at that time. Following the Bhuj earthquake of 2001, Karachi was reassigned to be in zone 4, the zone of highest hazard.
It is not clear, however, how long the engineering community will take to adopt the new guidelines, or whether (and how) the government will enforce the new zoning for Karachi. In any case, new building codes will not remedy the known and worrisome vulnerability of existing structures in which 14 million people now work and live.
Tsunami hazards exist in Karachi and its contiguous coastline that we have not examined in this article. The > 1-hour delay between the mainshock and the arrival of the damaging tsunami associated with the 1945 earthquake was very probably caused by submarine slumping offshore rather than direct uplift of the coast. If this were indeed the case, even a quite modest earthquake in the Kachchh region might be sufficient to trigger a submarine slide that would endanger the Karachi shoreline.
(1) Roger Bilham, Sarosh Lodi, Susan Hough, Saria Bukhari, Abid Murtaza Khan and S. F. A. Rafiqee, ‘Seismic Hazard in Karachi, Pakistan: Uncertain Past, Uncertain Future,’ Seismological Research Letters, November 2007; v. 78; no. 6; p. 601-613. (Copyright: Seismological Society of America)The event shocked people from Karachi to Indonesia. Fortunately, the earthquake, with a 7.9 magnitude at the Richter’s scale at its epicentre in Iran, spared Karachi of the devastation that the earthquakes of such a magnitude usually brought with them.
Kamran Khan recalled that the earthquake in Kashmir and its surrounding areas in 2005 with a magnitude of 7.8 at the Richter’s scale had claimed 80,000 lives. That earthquake had devastated entire cities.
So from the standpoint of past earthquakes, the one on Tuesday passed without creating havoc, to the relief of Karachiites.Come to think of Karachi, there is no denying the fact that the welfare activities in the shape of collection and distribution of Zakat money in Karachi are not matched by any other city in the world. No wonder, then, that the city remained unscathed in the face of such a gigantic earthquake on Tuesday, said Kamran Khan.
An expert in seismology, Dr Mona Lisa, while talking to Kamran Khan about the earthquake on Tuesday, said that an earthquake of a similar magnitude had struck in Dalbandin about three years ago, but fortunately, it had not caused any casualties or damage to property then.