Numbers of #Earthquakes in the form of minor shocks are shaking earth surface very frequently. Around fourteen minor shocks have stricken Delhi NCR in last two months. "Fore shock" and "aftershock" are relative terms. Fore shocks are earthquakes that precede larger earthquakes in the same location. An earthquake cannot be identified as a fore-shocks until after a larger earthquake in the same area occurs.
#Sanki designer has tried to analysed reasons for these #earthquakes and are these earthquakes are indicators of major earthquake in Delhi -NCR? This is for sure that continuous seismic activities is going on below the earth crust due to interaction of tectonic plates along the fault lines. Delhi has three fault-lines below Delhi-Faridabad, Mathura and Sohna Fault line and Delhi NCR is very near to Himalayan region just 200Km away. In the Himalayan region being in Zone 5 earthquakes in the range of Richter scale 7 to 8 are expected which poses major threats to the buildings of #Delhi NCR.
Delhi has micro zoning based on the vulnerability of the buildings erected in various locations to response of sub soil due to impact of energy released from the fault lines. The same intensity of earthquake can cause different damages to same types of buildings located in different subsoil conditions. Some types of soils have triggering effects to the waves generated from earthquakes and may cause havoc. The same has been explained in the context of Delhi including impact of liquefaction and response of weak soil in comparison to solid rocks. Delhi has been divided in three zones broadly as shown in the first level zoning maps and further divided into 8 to 9 zones depending upon the expected impact of waves on the subsoil.
Out of micro zoning Lutyens’ zone, having Parliament, central ministries and VIP residential buildings, also falls under the high risk zone but not vulnerable as areas along Yamuna bed.
Areas like Jawaharlal Nehru University, AIIMS, Chhatarpur and Naraina fall under the safest zone,Areas including Hauz Khas and Vasant Kunj are also among the low hazard zone.
while the high risk zone, mostly in patches, are concentrated ineast, central and northern parts. Delhi University’s north campus,Sarita Vihar, Gita Colony, Shakarpur, Paschim Vihar, Wazirabad, Rithala, Rohini, Jahangirpuri, Bawana, Karol Bagh and Janakpuri fall under the ‘high hazard zone’ having worst category of “very high” risk index. risk” index category.

Delhi has more than 5000, Gurugram has more than 1500 and Noida has more than 2000 multi storied buildings and Delhi has large areas under urban villages, illegal colonies and jj clusters in the form of slums which poses major threats during any shocks in the range of 5.0 to 6.5 even. Delhi has old monuments and buildings which also need to be retrofitted to cater any possible shocks. Gurugram has around 11 fault lines below this being more risky to have epicenter along fault lines. Noida being in Yamuna flood plains has weaker subsoil may cause liquefaction. Buildings being constructed need all the precautions and engineering skills to have more resistivity towards expected shocks and be more resilient. The Delhi needs to have master-plan based on the micro zonation to avoid high density built up areas in seismic sensitive locations. #Microzonation is only useful when being properly used in planning of settlements and to reduce impact of shocks. In the earthquake of Delhi in 1960 in the range of around 6.7 the epicenter was border of #Gurugram and Delhi at time Gurugram being small village faced devastation. We have to learn from history of these earthquakes. The Engineers and Architects to be trained to incorporate all the technical provisions in the buildings to increase resistivity of the buildings towards shocks. The buildings being erected in #Yamuna Flood plains and in the Eastern Delhi need lot of attention of policy makers to subvert and possible damage due to earthquakes.
We have not learnt form the collapse of building in Lalita Park in 2010 causing high human loss.
National Center for Seismology, Ministry of Earth Sciences Report Government of India on Microzonation of Delhi:
https://www.moes.gov.in/writereaddata/files/Delhi_microzonation_report.pdf
Delhi government has brought severeal GOs ehich are available in following links:
http://ddma.delhigovt.nic.in/wps/wcm/connect/8ba472004e9f4a099a85bf5dc9149193/buildbl1.pdf?MOD=AJPERES&lmod=-1591939727 of 10th February 2020.
http://ddma.delhigovt.nic.in/wps/wcm/connect/5ab627004e9f48bb9a7cbf5dc9149193/buildbl2.pdf?MOD=AJPERES&lmod=-1591939727 of 24th April 2020.
Most important is impementation of these GOs to avoid any mass mishappening.
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