Recent Earthquakes in Indian Subcontinent – Seminar
Guided By Dr. M.K. Shrimali, Dr. S.D. Bharti Submitted by: Anurag Sharma
After the Bhuj Earthquake
- North Andaman (Diglipur) Earthquake Of 14 September 2002
- Sumatra Earthquake And Indian Ocean Tsunami Of December 26, 2004
- 2005 North Kashmir Earthquake Of October 2005
- Sikkim Earthquake Of 14 February 2006
- 2011 Sikkim Earthquake
Earth and Its Interiors
- Earth cooled down
- masses became integrated together
- heavier ones going towards the center
- lighter ones rising up.
- Distinct layers of masses
- Earth primarily consists of four distinct layers
- The inner core
- The outer core
- The mantle
- and the crust
- Cluster of a number of plates of various sizes.
- This differential movement of the plates provides the basis of the foundation of the theory of tectonic earthquake.
- Flow of hot mantle upwards to the surface of the earth at the ridges due to convective circulation of the earth’s mantle.
- Radioactivity inside the earth.
- The U.S. Geological Survey (USGS) is responsible for providing information about earthquakes to other government agencies and to the public.
- The ML scale is often called the “Richter scale” by the press and the public.
- The moment magnitude scale (abbreviated as MMS; denoted as MW) is used by seismologists to measure the size of earthquakes in terms of the energy released
- The Medvedev-Sponheuer-Karnik scale, also known as the MSK or MSK-64, is a macro seismic intensity scale used to evaluate the severity of ground shaking on the basis of observed effects in an area of the earthquake occurrence.
North Andaman (Diglipur) Earthquake Of 14 September 2002
- On 14 September 2002, at
- 03:58:31 AM a
- ML 6.0 (IMD) Mw 6.5 (USGS)
- earthquake struck the Northern Andaman Island region of the Andaman & Nicobar Islands (Union Territory) of India.
- The epicenter 165 km NE from Port Blair, the administrative head quarters of A&N Islands sea about 24 km SE of Diglipur
- Location of the epicenter is 13.013°N 93.147°E (USGS), and the focal depth is 33 km.
- After shocks, the largest of them being M 5.3 on 14 September at 04:44 hours and
- M 5.2 on 15 September at 01:29 hours.
- Most severe seismic zone V of the Indian Seismic Zone map.
- Sandwiched between the Indo-Australian plate on the western side and the Eurasian plate in the north and the east.
- Region is witnessing a new phase of seismic activity.
- Ongoing post-seismic relaxation
- Shibpur, Aerial Bay Jetty and Kerala estimated to be VII on MSK scale.
- Many schools, community and residential buildings in
- Ramanagar and
- Kishorinagar suffered damage.
- Pounding damage was noted to jetty slabs.
- Truss members in the old cargo shed at the jetty and their connections failed.
- Mahatma Gandhi Degree College, developed cracks in their seismic deficient masonry and RC buildings.
- Traditional timber and bamboo structures were not affected to any noticeable degree on these islands, even in the areas of stronger shaking.
- Often these walls are not tied together to create the necessary box-action in masonry construction required for lateral resistance.
- No positive connection is provided between the wall and truss members resting on them.
- The Nabagram Panchayat building, suffered extensive damage to its ground floor columns near the side farthest from the stiffer side near the stair case block. Many of the columns were severely cracked and damaged near beam-column joints and at mid heights.
- No transverse stirrups (ties) were present over a length greater than 350 mm for the 200 mm wide columns.
- The RC columns were not designed for earthquake forces and required ductility.
- Creating the open first storey
- And by the lack of transverse stirrups in that storey where shear resistance is most needed.
Diglipur Harbour (Arial Bay Jetty)
The entire approach and berthing structure consists of
400 mm square reinforced concrete piles connected at the top by a box-type pier cap made of beams, columns, braces and slabs.
Pounding damage was afflicted to the jetty slab across at expansion joints, which was later repaired. Subsequent to the earthquake, vertical cracks were noticed on the piles supporting the jetty;
The flexible airstrip developed on unconsolidated marshy land developed cracks near the centerline. The cracks were filled with Grade 80/100 bitumen.
The terminal building under construction did not experience damage. However, the 1.5 m high boundary wall of the airport premises fell at many places.
SIKKIM EARTHQUAKE OF 14 FEBRUARY 2006
2011 SIKKIM EARTHQUAKE