Today we recognize The Great California Shakeout of 2015, on October 15, 2015, at 10:15 a.m., to bring awareness to the importance of earthquake preparedness. Dr. Ramesh P. Singh‘s recent article on the April 2015 Nepal earthquake reminds us how devastating these phenomena can be.
The recent earthquake [Magnitude 7.8] of April 25, 2015, occurred at 11:56 am (Nepal time) in Kathmandu, Nepal, located in Himalaya, and it took more than 8,000 lives. This earthquake destroyed about half a million buildings completely, and by surface ruptures and landslides it disrupted the road network in the hilly terrain. For more than two weeks, normal life in the area was interrupted.
The Himalayan region remains to be one of the most seismically active regions of the world. Due to continued collision of the Indian plate with the Eurasian plate, strain energy is progressively accumulated in the Himalayas and the buildup energy is released from time to time in the form of earthquakes.
In the last two centuries, the Himalayan region has experienced many great earthquakes (M ≥ 8). Adjacent to Himalaya is the Indo-Gangetic basin, which is home to 900 million people, major cities, including India’s capital Delhi. In the last 10 years many multi-story buildings have been mushrooming in cities in the foothills of Himalaya. Recently civil engineers working in India have expressed that 80% of buildings in Delhi may collapse in any future moderate earthquake occurring in the Himalayan region.
During the April 2015 7.8 earthquake, people living in major cities located in the Indo-Gangetic basin felt very strong shaking, especially in Delhi and surrounding regions, because the earthquake energy is transmitted very fast due to the underground configuration. Earthquakes are bound to occur in the region and it is impossible to avoid future earthquakes. The earthquake prediction/forecast is almost impossible, however earthquake active regions are well-known around the globe.
During an earthquake, loss of life occurs due to collapsing buildings, and this is due to poor quality construction, weak foundations and builders not following the building codes. Multi-story buildings are being built at a fast rate, so whether such buildings are built following building codes is an important question. The building codes must be updated using observed ground motion parameters from the past earthquake data.
When I was professor at the Indian Institute of Technology, Kanpur, my group and I had developed an attenuation relation which estimates acceleration at any location within a radius of 400 km. This attenuation relation was published in refereed international journals in 1995 and 1996. Soon after the April 25, 2015, earthquake, I collaborated with Dr. Raed Ahmed from Syria (formerly one of my master’s students) and we found that the earthquake’s ground motion fits well with the attenuation relation published by my group in 1995 and 1996.
The results of this detailed analysis of ground parameters has been recently published online in Natural Hazards published by Springer (title of article, Attenuation Relation Predicted Observed Ground Motion of Gorkha Nepal Earthquake of 25 April 2015, DOI: 10.1007/s11069-015-1969-2).
The building codes must be strictly followed in developing countries like India, Nepal, Pakistan, China, Bangladesh and these building codes must be updated based on the observed ground motion data from earthquakes. Every country must enhance their network of ground motion accelerometers.
If buildings are made without engineering design and building codes, they will not sustain the ground motion of an earthquake, as was the case of the five-story primary school building which collapsed, killing young children and teachers, during Wenchuan earthquake of 12 May 2008. The photo I recently took while visiting the Wenchuan area in July is an eye opener to all of us and we must try to raise our voice that at least governments in developing countries must design school buildings following building codes.
Dr. Susan Hough, Senior Scientist at USGS/CALTECH and I are organizing a Union Session on Nepal earthquake during the Fall AGU meeting to be held in San Francisco December 14-18, 2015. Eight speakers from India, Nepal, Europe and USA have been invited to present all the aspects of Nepal earthquake which will be video recorded.