November 26, 2007

Epicenter of Earthquake Was Delhi University: US Geological Survey

According to USGS, the epicentre of Delhi earthquake was just south of Delhi University near GT road, not Delhi-Haryana border as media reports have said. (See UPDATE 26-Nov, 4.15PM)

Delhi experienced what's being called a "moderate" earthquake this morning. It recorded 4.6 on Richter scale. I've felt earthquakes in the past and this was by far the strongest because its epicenter was right in Delhi.

However, there seems to be some confusion over where exactly lies the epicentre in or around Delhi. Media reports mention Delhi-Haryana border but the Delhi Haryana border is not a single location, it stretches for several kilometers. However, the latitude and longitude figures released by India's meteorological department does not match this.

Epicenter According to the Met Department

According to Indiainfo and ZeeNews,
The epicenter of the tremor was at the Delhi-Haryana border at 28.6 N latitude and 77.9 E longitude. Precisely it was centered around 10 kms from Bahadurgarh in Haryana.
This does not make any sense because those figures are for a location in U.P nowhere close to Delhi or Haryana. Enter 28.6°N, 77.9°E in Google Maps and you get this.


(Scale: 20km)

As you can see, the epicenter according to the met department is not consistent with the statement that it's on Delhi-Haryana border. It's actually about 100km East of the point where Bahadurgarh is. (see UPDATE below)

Epicenter According to U.S. Geological Survey

The National Earthquake Information Center (NEIC), part of U.S Geological Survey maintains a database of earthquakes around the world. According to their data, the epicenter location was actually right in the middle of North Delhi just south of Delhi University.



Enter 28.677°N, 77.204°E in Google Maps and you get this.


(Scale: 2km)


(Scale: 500m)

The figures released by USGS have a location uncertainty of +/- 18km but that still doesn't put it anywhere close to the figures provided by the met department.

I will update this post when I have more info but if you know a more reliable source of the epicenter location, please leave a comment.

UPDATE 4.15PM: Correct Met Dept Location Now Confirmed

It seems the media reports picked up wrong Longitude figure released by the Met department. Met Department's list of earthquakes in November available on its website (scroll down to 25) puts the Longitude at 77.0E instead of 77.9E as reported in news reports mentioned above.

This puts their stated location at Delhi-Haryana border near Najafgarh or about 10km from Bahadurgarh. View location on Google Maps.


(Scale: 10km)

The Amateur Seismic Centre (ASC), an independent centre based in Pune, continues to go with the USGS data source and puts the epicenter at Malka Ganj-Kamla Nagar in Delhi University area, as mentioned above.

Note that both USGS and Met department locations are from their preliminary reports.

UPDATE 8.00PM: I wrote to ASC's Stacey Martin to find out which data is more credible. Stacey kindly wrote back that eventually India Meteorological Department (IMD) figures will be more accurate since its monitoring station is in Delhi itself while USGS/NEIC's closest monitoring station is in Kabul. However, as of right now, the latter has provided figures up to three decimal places so at the moment ASC is going with NEIC's epicenter in North Delhi.

Since this is only preliminary data, it's likely to be corrected and the final IMD location will only be available in the public domain in 18-months due to CTBT constraints.

Past Earthquakes in Delhi Region

Here is some historical information on earthquakes in Delhi, taken from ASC report of today's quake.
This is one of the strongest earthquakes in the Delhi region since 2001 and the biggest since 1960. Prior to this latest earthquake, the strongest local earthquakes to have originated within the Delhi metropolitan area since the 1960 Gurgaon earthquake was a Mb=4.3 earthquake in the Dwarka-Najafgarh area on 28 April 2001 that caused minor damage & widespread panic. The strongest known earthquakes in the Delhi region include the M6.0 Khurja-Bulandshahr earthquake on 10 October 1956, the M6.0 Gurgaon earthquake on 27 August 1960 and the Mb=5.6 Moradabad earthquake on 15 August 1966. Historically, the 15 July 1720 earthquake in the Delhi region caused the greatest damage in the city causing many deaths and widespread damage including knocking down large parts of the Shaharepanah (city wall) in Old Delhi from Kabuli Gate to Lal Darwaza and the battlements of the Fatehpuri Masjid.

UPDATE 30-Sep-14 - Useful resources: Sharon Thornton, Research Coordinator at The International Union of Geodesy and Geophysics (IUGG) wrote in to suggest a resource she helped create covering: earthquake data for years 2005 - 2014, most devastating earthquakes 2005 - 2013, earthquake glossary. The resource can be found here: Earthquakes Data Magnitude 5.0 and Over 2005 - 2014. She also suggests two more useful resources: Seismic Monitor and Quakes - Live Earthquakes Map.

7 Comments so far      

Anonymous Ravi Sagar:

So the epicenter was clock tower near DU. You know I crossed clock tower last night while coming back from marriage!!!

I looked at the tower and was not amazed to see it not working. I never imagined that that place can be an epicenter of an earth quake.

Thank God the quake was not too strong and everything is fine. Earth quakes are scary.

26 November 2007 at 22:14:00 GMT+5:30 link  
Anonymous Anonymous:

Hi,
I still believe, IMD location is better. Please visit IMD web-site.
It is Latitude 28.6 degree North and longitude 77.0 degree East. The reason being, IMD has a good set of instrumentation in and around Delhi. However, these are Preliminary location estimate and may change after pooling the data from several stations. The location accuracy, also depends while fixing the depth of Focus, and calculating the latitude and longtitude. IMD location, lies at a distance of about 11 km NW from International Airport and is close to Najafgargh drain. Also, it may be noted that magnitude estimates may also vary about 0.2 to 0.3 units.
The duration of shock was only few seconds as expected at such a small magnitude 4.3 earthquake. The question lies, what would have happened, had magnitude of this earthquake would have been (around 7.0 or higher on Richter scale ???

Sushil Gupta
General Manager, Risk Management Group,A-7, RMSI, Sector-16, Noida-201301

26 November 2007 at 22:43:00 GMT+5:30 link  
Anonymous Anonymous:

IMD reporting appears to be ok. The direction of quake was felt from east to west in gurgaon

26 November 2007 at 23:45:00 GMT+5:30 link  
Anonymous Anonymous:

Mistake ! the direction was from west to east

26 November 2007 at 23:46:00 GMT+5:30 link  
Blogger Manu Sharma:

I live in Gurgaon too and I think I felt the direction to be from North-South. It felt like someone was trying to throw me sideways off the bed (which is on East-West axis).

Still, none of that proves anything, unless we know the fault line and direction of the force at the epicenter.

27 November 2007 at 10:57:00 GMT+5:30 link  
Blogger Manu Sharma:

Incidentially, the news media continues to get it wrong. Today's Hindustan Times in its page 2 feature "City Shaken By Dawn Tremors" puts the epicenter at Bahadurgarh as determinted by IMD but in a table next to the story, it uses the coordinates of NEIC/USGS site (Delhi Univ) as the location!

The said article is available online but the corrdinates are only mentioned in the print feature.

It also gets something else wrong. It quotes DG IMD saying that Delhi has never been epicenter of a major quake in the past. This is simply untrue. As I quote in the last paragrapgh, we've had TWO 6.0 intensity earthquakes with epicenter in and around Delhi besides a third one not too far away.

First was the Khurja-Bulandshahr earthquake in 1956. Khurja, in U.P, is a mere 35km from Delhi. Bulandshahr is 84km. The second 6.0 intensity earthquake ocurred only four years later in 1960 and had its epicenter in Gurgaon. We also had a 5.6 intensity earthquake in Moradabad (U.P) which is 106km from Delhi.

So either the Director General of IMD R.C. Bhatia is misinformed or he has been misquoted by another clueless journalist. This is particularly bad example of poor journalism because they had a full day to write this story.

27 November 2007 at 11:40:00 GMT+5:30 link  
Anonymous Anonymous:

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28 November 2009 at 12:50:00 GMT+5:30 link  

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