by David L. Hagen
Nepal just experienced a great 7.8 magnitude earthquake on April 25th, 2015 with major (6.7 and 6.6 magnitude) aftershocks..
See: Major earthquake hits Nepal: Alexandra Witze, Nature News, 26 April 2015, doi:10.1038/nature.2015.17413
Scientists have long warned that mounting seismic stress put region near Kathmandu at risk for a severe tremor. . . .A magnitude 7.8 earthquake hit just 80 kilometres northwest of Kathmandu on 25 April, crumbling buildings and devastating much of the city. The ground shook well beyond Nepal’s borders, into Tibet and northern India, in one of the worst natural disasters to strike the Himalayas in years; thousands of people are feared dead.
Now the Nepal Earthquake Poses Challenge to International Aid Agencies
At least another 5900 have been injured. About 6 million live in the earthquake affected region. The transportation network is crippled and power is lost in parts of the country. Rain descended on Kathmandu Sunday in a foretaste of the summer monsoon rains starting in June.
Historical and Predicted Earthquakes in Nepal
The South Asian subcontinent is colliding with Asia, creating the Himalayan mountains. This causes frequent large earthquakes as well as numerous smaller ones.
1934 Nepal-Bihar Earthquake
An 8.2 magnitude earthquake occurred in Nepal and northern Bihar on 15 January 1934. with about 19,000 deaths (7,253 died in Bihar plus 10,800 to 12,000 deaths in Nepal). See publications on the 1934 Nepal earthquake.
Nepal Earthquake Studies & Reports
‘Great quake overdue’: A study had warned just two months ago
Less than two months before the 7.9-magnitude earthquake that rocked Nepal and a vast swathe of northern India on Saturday, a team of Indian scientists had predicted “a great earthquake” in the geographical region around the central Himalayas.
Medieval pulse of great earthquakes in the central Himalaya: Viewing past activities on the frontal thrust, C. P. Rajendran, Biju John, & Kusala Rajendran, J. Geophysical Research, Solid Earth V. 120 #3 March 2015 pp 1623-1641
The Himalaya has experienced three great earthquakes during the last century—1934 Nepal-Bihar, 1950 Upper Assam, and arguably the 1905 Kangra. Focus here is on the central Himalayan segment between the 1905 and the 1934 ruptures, where previous studies have identified a great earthquake between thirteenth and sixteenth centuries. Historical data suggest damaging earthquakes in A.D. 1255, 1344, 1505, 1803, and 1833, although their sources and magnitudes remain debated. We present new evidence for a great earthquake from a trench across the base of a 13 m high scarp near Ramnagar at the Himalayan Frontal Thrust. The section exposed four south verging fault strands and a backthrust offsetting a broad spectrum of lithounits, including colluvial deposits. Age data suggest that the last great earthquake in the central Himalaya most likely occurred between A.D. 1259 and 1433. While evidence for this rupture is unmistakable, the stratigraphic clues imply an earlier event, which can most tentatively be placed between A.D. 1050 and 1250. The postulated existence of this earlier event, however, requires further validation. If the two-earthquake scenario is realistic, then the successive ruptures may have occurred in close intervals and were sourced on adjacent segments that overlapped at the trench site. Rupture(s) identified in the trench closely correlate with two damaging earthquakes of 1255 and 1344 reported from Nepal. The present study suggests that the frontal thrust in central Himalaya may have remained seismically inactive during the last ~700 years. Considering this long elapsed time, a great earthquake may be due in the region.
The heavy South Asian 2014 Monsoon rains were reported as: Climate Change’s Role in Indian Pilgrim Deaths
Floods and landslides tore vulnerable buildings and villages from their feeble riverside roots, flushing their ramshackle remains downstream. They left an estimated 100,000 without shelter or food, in many cases for more than 10 frigid and soggy days, and stole away the lives of more than 5,000 of them. . . .
“The Stanford University-led research unearthed tenuous links between the tragedy and rising green house gas levels. Perhaps more strikingly, however, the paper helped to illuminate the institutionalized vulnerability of vast swaths of mountainous Asia — where tens of millions of humble-living residents contribute little to global warming — to the vagaries of a climate that’s increasingly prone to turn vicious.
Emergency and Earthquake Preparedness in Nepal
Quake experts: Nepal “A Nightmare Waiting to Happen”. This 2015 Nepal quake is the 5th significant quake in the last 205 years, including the massive 1934 quake. Just a week before Nepal’s earthquake, 50 experts gathered in Kathmandu to prepare for what they knew was coming – but did not know when. Kathmandu was very congested, overdeveloped and shoddily built. How should they prepare for “the big one” like the 1934 earthquake that flattened Kathmandu?
To provide transformational increases in knowledge of the distributions of primary and secondary earthquake hazards in the continental interiors.
• To identify pathways to increased resilience in the populations exposed to these hazards.
• To secure these gains over the long term by establishing a well-networked, trans-disciplinary partnership for increasing resilience to earthquakes.
On April 12th, Hari Kumar of GeoHazards International updated a late 1990s report summarizing the Kathmandu Valley risks:
“With an annual population growth rate of 6.5 percent and one of the highest urban densities in the world, the 1.5 million people living in the Kathmandu Valley were clearly facing a serious and growing earthquake risk,”
Poverty and Building codes
Grinding poverty is the most pressing issue for most people. Nepal has a per capita GNI of ~$750 about the lowest in South Asia. Except for landslides, which in this case are a serious problem, Jackson said “it’s buildings that kill people not earthquakes.” Poverty and poor (or no) building codes amplify damage during earthquakes and other disasters by several orders of magnitude. USGS seismologist David Wald said:
the same level of severe shaking would cause 10 to 30 people to die per million residents in California, but 1,000 maybe more in Nepal, and up to 10,000 in parts of Pakistan, India, Iran and China
Most Nepalese buildings were built with no building codes and little regard for earthquakes. Nepal’s civil war further impacted planning. Kathmandu’s old city had very weak medieval brick construction with lanes too narrow for emergency vehicles or construction equipment. Even current codes are weak and do not redress past construction.
“In the 1988 Nepal earthquake, the destruction of 14,000 classrooms was significant, but more so was the fact that 300,000 children couldn’t go to school for years afterwards. When an earthquake destroys schools, it takes away the children’s future —and with it, the future of the country itself.”
Madhab Mathema, Former Senior Human Settlements Advisor, United Nations Center for Human Settlements
Lalitpur Sub-Metropolitan City (LSMC) “announced the implementation of Nepal National Building Code (NBC) in building permit process on the occasion of Earthquake Safety Day on 16th January, 2003.”
The UN Center for Regional Development helps countries develop building codes for earthquake preparedness. including a Housing Earthquake Safety Initiative 2007. e.g., UNCRD published a Handbook on Building Code Implementation: Learning from Experience of Lalitpur Sub-Metropolitan City, Nepal Jan. 16, 2008
Nepal’s local inheritance rights results in buildings split vertically to give equal share as to brothers. This causes thin rickety homes with more floors added for living space. Both social reform and building codes are needed to redress this distortion from prudent planning and earthquake preparedness.
Secondary effects typically contribute 21.5% of earthquake fatalities. e.g., Marano, K.D., Global earthquake casualties due to secondary effects: a quantitative analysis for improving rapid loss analyses Nat Hazards (2010) 52:319–328, DOI 10.1007/s11069-009-9372-5 [link]
Earthquakes often cause landslides in mountaineous areas. Tom Robinson (U. Cantebury, New Zealand) developed a landslide susceptibility pattern that has been updated on 26 April 2015 from the USGS ShakeMap. Such mapping can help people prepare for landslides, and to rapidly direct rescue workers to the worst effect areas. e.g., Nepal’s 2015 earthquake may cause ~ 30 sq km of landslides compared to the 396 sq km for the Mw 7.9 Wenchuan earthquake in China. The Wenchuan earthquake caused some 20,000 deaths. Yin, Y. et al. Landslide hazards triggered by the 2008 Wenchuan earthquake, Sichuan, China Landslides, June 2009, Vol. 6, #2, pp 139-152. A simple extrapolation of landslide are might suggest about 1,500 landslide deaths in Nepal.
Heavy monsoon rains often cause landslides. Dahal, R.K. & Hasegawa, S., Representative rainfall thresholds for landslides in the Nepal Himalaya”, Geomorphology 100 (2008) 429-443. e.g., Darjeeling India, in the Himalayan foothills (6710 ft) lies ~80 miles SE of Mt. Everest. It averages ~ 3092 mm (122”) of rain/year. An average summer monsoon rainfall of 2489.08 mm (98”) occurs between the 2nd week of May and the 3rd week of October. Tropical cyclones or depressions from the Bay of Bengal to the Himalayan mountains cause heavier sustained rains. When these occur on top of saturated ground at the end of the summer monsoon they can cause severe landslides. e.g.
. . .a disastrous landslip occurred on the 24th September, 1899, in and around Darjiling town due to unprecedented rainfall of 1065.50 mm (42”), killing 72 persons . . .
In October 1968 a tropical depression reportedly dropped 23” of rain in 36 hours, causing some 20,000 landslides.
Due to incessant and heavy rain of 1121.40 mm (~44”) between 3rd and 5th October, 1968 there were numerous landslides accompanied by unprecedented floods in the Tista and other rivers. (2 roads and more than 3 bridges ) were either washed away or severely damaged. The death-toll, officially estimated was 677 while unofficial reports placed the figure much higher. . .
Basu, S.R., & De, S.K., “Causes and Consequences of landslides in the Darjiling-Sikkim Himalayas, India”, Geographia Polonica, 76, 2, 37-52, Autumn 2003, PL ISSN 0016-7282.
Floods from landslide dams
Earthquake and monsoon caused landslides can temporarily dam rivers. This causes a severe torrential flood when the water breaks through, destroying downstream towns.
An earthquake hitting saturated Himalayan hills would likely cause far greater havoc than similar earthquakes in dry areas. (e.g., near the end of the summer monsoon in eastern Nepal/Darjeeling region compared to during the dry season in the western Himalayas.) Medium range weather forecasting could warn regional, national and international emergency response organizations of such potential hazards. Hasegawa, S. et al., Causes of large-scale landslides in the Lesser Himalaya of central Nepal, Environ. Geol. DOI 10.1007/s00254-008-1420-z.
Deforestation & Flooding
Nepal deforestation and climate change have been posited for enhancing downstream flooding such as in Bangladesh. Peak flows can be affected by changes in land use and land cover.
Nepal, S. et al., Upstream-downstream linkages of hydrological processes in the Himalayan region. Ecological Processes, Springer, 9 Sept. 2014 DOI 10.1186/s13717-014-0019-4
The paper studies the linkages between the changes in the physical environment of upstream areas (land use, snow storage, and soil erosion) and of climate change on the downstream water availability, flood and dry season flow, and erosion and sedimentation. It is argued that these linkages are complex due to the extreme altitudinal range associated with the young and fragile geology, extreme seasonal and spatial variation in rainfall, and diversity of anthropogenic processes.
Indoor and Outdoor Air pollution
While dramatic, catastrophic earthquakes and floods should be evaluated in context of slower but even deadlier air pollution. The World Health Organization (2014) reports that:
in 2012 around 7 million people died – on in eight of total global deaths – as a result of air pollution exposure. . . . air pollution is now the world’s largest single environmental health risk. WHO Fact Sheet No. 292 March 2014.
- Around 3 billion people cook and heat their homes using open fires and simple stoves burning biomass (wood, animal dung and crop waste) and coal.
- Over 4 million people die prematurely from illness attributable to the household air pollution from cooking with solid fuels.
Burden of disease from Household Air Pollution for 2012 WHO 2014.
Globally, each year two to three times as many people die as in ALL earthquakes since 1900.
Severe outdoor air pollution is also creating major health hazards in developing country cities. e.g., Kathmandu traffic police are exposed to 51.2 ug/m3 average up to 500 ug/m3 per hour. World Health Organization recommends an ambient PM2.5 guideline (25 μg/m3). Kathmandu’s average air quality is typically several times worse then WHO maximum guidelines.
Shrestha, HS et al., A cross-sectional study of lung functions in traffic police personnel at work in Kathmandu Valley, Nepal ACCLM 1(1)42-48(2015)
Policies for Monsoons, Earthquakes, and Climate Change
Since 2014, Himalayan Climate (a.k.a. Global warming) and Himalayan Monsoons recently received 350% and 270% of the publications on Himalayan Earthquakes. I.e., since 2014: Himalayan Climate 7030 pubs; Himalayan Monsoons 5300 pubs; Great Earthquakes Himalaya 1990 pubs.
Natural variability in earthquakes and monsoon rains in the Himalaya region appear to have far greater human impact than climate change. Judith Curry gave testimony on the small climate sensitivity of recent evaluations and the very large uncertainties involved in evaluating climate change.
Consequently, governments should reallocate funding for response to civil disasters and on preparing resilient structures with corresponding building codes to prudently manage earthquakes and monsoon floods and landslides. These may then be adjusted for the apparent minor changes to be expected from global warming.
The Copenhagen Consensus has addressed Air Pollution in a detailed Air Pollution Assessment Paper. The Australian Government is supporting further work at the new Australian Consensus Centre at the University of Western Australia.
PREPAREDNESS BIBLIOGRAPHY – In context of Nepal [Bibliography]
Ways to donate for the Nepal Earthquake Relief [Donate]
PS Caveat emptor. I rapidly prepared this review as a researcher/citizen with a general interest in the subject. I look forward to feedback from those trained in these issues to extend and correct these comments and references.
David L. Hagen