Question: What was the magnitude of the earthquake that, in September 2011, affected the city where the Gandhi Smriti is located?

full_context: Document 1: Houston: The Houston area has over 150 active faults (estimated to be 300 active faults) with an aggregate length of up to 310 miles (500 km), including the Long Point–Eureka Heights fault system which runs through the center of the city. There have been no significant historically recorded earthquakes in Houston, but researchers do not discount the possibility of such quakes having occurred in the deeper past, nor occurring in the future. Land in some areas southeast of Houston is sinking because water has been pumped out of the ground for many years. It may be associated with slip along the faults; however, the slippage is slow and not considered an earthquake, where stationary faults must slip suddenly enough to create seismic waves. These faults also tend to move at a smooth rate in what is termed "fault creep", which further reduces the risk of an earthquake.
Document 2: Martyrs' Day (India): 30 January is the date observed at the national level. The date was chosen as it marks the assassination of Mohandas Karamchand Gandhi in 1948, by Nathuram Godse. On Martyr's Day the president, the vice president, the prime minister, the defence minister, and the three Service Chiefs gather at the samadhi at Raj Ghat memorial and lay wreaths decorated with multi-colour flowers. The armed forces personnel blow bugles sounding the Last Post. The inter-services contingent reverse arms as a mark of respect. A two - minute silence in memory of Indian martyrs is observed throughout the country at 11 AM. Participants hold all - religion prayers and sing tributes.
Document 3: Sevagram: Sevagram is a small village, located about 8 km from Wardha. Mahatma Gandhi set up his ashram in the outskirts of the village when barely 1,000 people lived there. Seth Jamnalal Bajaj of Wardha, a disciple of Mahatma Gandhi, made available to the ashram about 300 acres (1.2 km) of land. Near the ashram there is a museum where artifacts of India's freedom struggle are preserved.
Document 4: April 2015 Nepal earthquake: Thousands of houses were destroyed across many districts of the country, with entire villages flattened, especially those near the epicenter.
Document 5: Istanbul: Istanbul is near the North Anatolian Fault, close to the boundary between the African and Eurasian Plates. This fault zone, which runs from northern Anatolia to the Sea of Marmara, has been responsible for several deadly earthquakes throughout the city's history. Among the most devastating of these seismic events was the 1509 earthquake, which caused a tsunami that broke over the walls of the city and killed more than 10,000 people. More recently, in 1999, an earthquake with its epicenter in nearby İzmit left 18,000 people dead, including 1,000 people in Istanbul's suburbs. The people of Istanbul remain concerned that an even more catastrophic seismic event may be in the city's near future, as thousands of structures recently built to accommodate Istanbul's rapidly increasing population may not have been constructed properly. Seismologists say the risk of a 7.6-magnitude or greater earthquake striking Istanbul by 2030 is more than 60 percent.
Document 6: 2008 Sichuan earthquake: According to a study by the China Earthquake Administration (CEA), the earthquake occurred along the Longmenshan fault, a thrust structure along the border of the Indo-Australian Plate and Eurasian Plate. Seismic activities concentrated on its mid-fracture (known as Yingxiu-Beichuan fracture). The rupture lasted close to 120 sec, with the majority of energy released in the first 80 sec. Starting from Wenchuan, the rupture propagated at an average speed of 3.1 kilometers per second 49° toward north east, rupturing a total of about 300 km. Maximum displacement amounted to 9 meters. The focus was deeper than 10 km.
Document 7: Gandhi Memorial Museum, Madurai: Gandhi Memorial Museum, established in 1959, is a memorial museum for Gandhi located in the city of Madurai in Tamil Nadu, India. Known as Gandhi Museum, it is now one of the five Gandhi Sanghralayas (Gandhi Museums) in the country. It includes a part of the blood-stained garment worn by Gandhi when he was assassinated by Nathuram Godse.
Document 8: New Delhi: With a total area of 42.7 km2 (16.5 sq mi), New Delhi forms a small part of the Delhi metropolitan area. Because the city is located on the Indo-Gangetic Plain, there is little difference in elevation across the city. New Delhi and surrounding areas were once a part of the Aravalli Range; all that is left of those mountains is the Delhi Ridge, which is also called the Lungs of Delhi. While New Delhi lies on the floodplains of the Yamuna River, it is essentially a landlocked city. East of the river is the urban area of Shahdara. New Delhi falls under the seismic zone-IV, making it vulnerable to earthquakes.
Document 9: Tomb of the Unknown Soldier: India Amar Jawan Jyoti, New Delhi Burning in a shrine under the arch of India Gate since 1971 is the Amar Jawan Jyoti (the flame of the immortal soldier) which marks the Tomb of the Unknown Soldier. The shrine itself is a black marble cenotaph with a rifle placed on its barrel, crested by a soldier's helmet. Each face of the cenotaph has inscribed in gold the words ``Amar Jawan ''(Immortal Warrior) in Hindi (Devanagri script). The Prime Minister of India pays homage to the country's fallen soldiers along with the Chiefs of Staff of each arm of the Armed Forces on each Republic Day of India.
Document 10: National Gandhi Museum: The National Gandhi Museum or Gandhi Memorial Museum is a museum located in New Delhi, India showcasing the life and principles of Mahatma Gandhi. The museum first opened in Mumbai, shortly after Gandhi was assassinated in 1948. The museum relocated several times before moving to Raj Ghat, New Delhi in 1961.
Document 11: New Delhi: Gandhi Smriti in New Delhi is the location where Mahatma Gandhi spent the last 144 days of his life and was assassinated on 30 January 1948. Rajghat is the place where Mahatma Gandhi was cremated on 31 January 1948 after his assassination and his ashes were buried and make it a final resting place beside the sanctity of the Yamuna River. The Raj Ghat in the shape of large square platform with black marble was designed by architect Vanu Bhuta.
Document 12: New Delhi: New Delhi lies on several fault lines and thus experiences frequent earthquakes, most of them of mild intensity. There has, however, been a spike in the number of earthquakes in the last six years, most notable being a 5.4 magnitude earthquake in 2015 with its epicentre in Nepal, a 4.7-magnitude earthquake on 25 November 2007, a 4.2-magnitude earthquake on 7 September 2011, a 5.2-magnitude earthquake on 5 March 2012, and a swarm of twelve earthquakes, including four of magnitudes 2.5, 2.8, 3.1, and 3.3, on 12 November 2013.
Document 13: Seattle: Due to its location in the Pacific Ring of Fire, Seattle is in a major earthquake zone. On February 28, 2001, the magnitude 6.8 Nisqually earthquake did significant architectural damage, especially in the Pioneer Square area (built on reclaimed land, as are the Industrial District and part of the city center), but caused only one fatality. Other strong quakes occurred on January 26, 1700 (estimated at 9 magnitude), December 14, 1872 (7.3 or 7.4), April 13, 1949 (7.1), and April 29, 1965 (6.5). The 1965 quake caused three deaths in Seattle directly, and one more by heart failure. Although the Seattle Fault passes just south of the city center, neither it nor the Cascadia subduction zone has caused an earthquake since the city's founding. The Cascadia subduction zone poses the threat of an earthquake of magnitude 9.0 or greater, capable of seriously damaging the city and collapsing many buildings, especially in zones built on fill.
Document 14: Southern California: Many faults are able to produce a magnitude 6.7+ earthquake, such as the San Andreas Fault, which can produce a magnitude 8.0 event. Other faults include the San Jacinto Fault, the Puente Hills Fault, and the Elsinore Fault Zone. The USGS has released a California Earthquake forecast which models Earthquake occurrence in California.
Document 15: Raj Ghat and associated memorials: Rajiv Gandhi Prime Minister of India 1991 Veer Bhumi Land of Brave 15 A large lotus in full bloom carved out of stone surrounded by 46 small lotuses to signify the years he lived; rocks from all the states of India are spread around.
ground_truth: 4.2-magnitude
sub_queries: In which city is the Gandhi Smriti located? Answer: New Delhi
What was the magnitude of the earthquake that affected New Delhi on September 2011? Answer: 4.2-magnitude