The Mw 7.8 Gorkha earthquake 25 April 2015 and lessons for
resilient infrastructure and communities
Sean Wilkinson, Matt DeJong, Barnali Ghosh, Paul Burton, Michael Whitworth, Raju Suryanarayana,Guillermo Franco, Time White, Sarah Tallet Williams, Viviana Novelli, Arthur Trieu, Tristan Lloyd, Katsu Goda
RESNET – my day jobSean Wilkinson, Richard Dawson, Kevin Anderson, Ruth Wood, Ian Cotton, Peireluigi Mancellara, Sarah Mander
Demand and supply scenarios (WP2)
Operational resilience
Infrastructure resilience
Climate Model (WP1)
Power Systems Model (WP3)
Social and broader implications (WP5)
Resilience enhancement(WP4)
Component Fragility (WP3)
RAWEENS mapping for Vwind_max = 40m/s
3
Maximum daily demand, winter and summer (2010,2030, 2050)
The Mw 7.8 Gorkha earthquake 25 April 2015
• 25 April 2015 (Saturday) ,11:56 NST• magnitude of Mw 7.8 and a • maximum EMS98 Intensity of IX • hypocenter at a depth of 15 km • killed more than 9,000 people • injured more than 23,000. • Hundreds of thousands of people were made homeless• Triggered an avalanche on Mount Everest, killing at
least 19• destroyed Centuries-old buildings at UNESCO World
Heritage sites• Many landslides in remote hills• A major aftershock occurred on 12 May 2015 at 12:51
NST Mw 7.3
2004 Lifeline Damage Boxing Day Tsunami
Robust systems
2009 Sumatra Earthquakle - Landslides
View from high point of survey
House displaced down the slope during the landslideVillage mosque destroyed
Damaged pedestrian bridge still heavily
used by the residents
2009 Sumatra Earthquake
2011 Christchurch - Liquefaction
• Liquefaction affected much of city centre and eastern suburbs • Occurred where recent river
alluvium, swamp, estuarine alluvium, reclaimed full present (silty and sandy soils) • Shallow water table• Rarely affected dunes
Lateral spreading
Lifelines and Critical Infrastructure
Mission Objectives• Assess Building Performance and identify areas for improvement• To understand how soil properties affected ground shaking and investigate if this could
be why the damage and deaths were less than expected.• Assess the impact of landslides on the Nepal road network and how this impacted on
relief efforts• To understand the governmental/donor/private setup for funding emergency and
recovery activities• Evaluation of performance of cultural heritage structures• Collect earthquake records and information relating to seismicity• Identification of earthquake reconnaissance research needs and applications,
particularly related to image processing and computer vision
Himalayan earthquake belt:historical earthquakes
Kashmir 2005 7.6 MW
Gorkha 20157.8 MW
Seismicity: 1900 to 25 April 2015
1916 earthquake
M=7.0
Great 1934 earthquake M=8+
Seismicity: 1900 to 12 October 2015
Mainshock M=7.8
Main aftershock
M=7.3
Great 1934 earthquake M=8+
1916 earthquake
M=7.0
Seismicity: 25 April to 12 October 2015
Mainshock M=7.8
Main aftershock
M=7.3
Geotechnical Aspects
(Adan & Ulusay, 2015) (Urju News, 2015)(Goda et al., 2015)
Foundation DamageSiddthol Region, Kathmandu
Siddthol Region, Kathmandu
Jyamirdanda Hill Top Town,South Of Kathmandu
DolalghatHill Top Town,South Of Kathmandu
Site Effects: Kathmandu Valley
(Aydan & Ulusay, 2015)
Microtremor H/V
Microtremor H/VBalaju Park Hotel Annapurna
Eurocode Site Class E Eurocode Site Class C
Site Amplification In Balaju Park
0 1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
0.6
0.7Balaju Park, Siddthol, Soil Response Compared to Spectra
Code Rock Site
Code Medium Soil
Code Soft Soil
HNE
HNN
HNZ
Period (s)
Ampl
ifica
tion
(g)
Liquefaction
(Aydan & Ulusay, 2015)
Topographical Amplification
Structural Response
Associated Press
Structures in Kathmandu• Vast majority = little visible structural damage.• Energy at relevant natural frequencies (< 1 Hz) was moderate.• Base shear not excessive• Many building were not tested.
• However:• Still considerable damage• Long pulses cause overturning (out-of-plane) failure:
• Concrete structures = less susceptible • Unreinforced masonry = more susceptible
Soft/weak storey failure
Dhapesi – Horizon Housing• Structural damage not visible from exterior• Extensive infill damage
Cultural Heritage
Dharahara Tower
Bridges
Remote Mountain Communities
Landslides occurrence map
RMC-Landslide
RMC-Buildings
GPS track of landslide survey
RMC-Landslide
Nepal EarthquakeSocioeconomic Aspects
Effects on Sectors
EEFIT Observations- Indeed the most seriously affected sector is housing but the
damages were contained to:- Mountain communities- Weak masonry structures- Historical structures- Apartment blocks in specific –probably soil-susceptible- areas
Tourism will suffer due to historical losses
Small Loss to Transport and Sanitation
Impact of Earthquake on Insurance Industry• Country is mostly under insured – most insurers reinsure
• Overall impact of the Nepal event on Insurance industry is minimal
*As of June 2015
~13m USD
TOTAL is ~130m USD
Market distortions• Labourer daily rates have doubled pre vs post earthquake• National shortage of CGI sheets:• 4 CGI sheet factories in Nepal, estimated to be able to satisfy less than 40% of
current national demand. • Agencies have looked to import from India, but stockpiles are left on border
as they have been designated a non relief item by GoN and subject to 40% import tax. Agencies wish to avoid a costly precedent.
• Timber in short supply• Timber already less common in construction. So an existing shortage
exacerbated.• Fuel shortage ongoing
Conclusion of Financial Impacts• Flash Appeal of 400m USD (60% reached)• Risk transfer: little, potential for development
Conclusions• Reinforced concrete Building performed better than expected because of unique
characteristics of this earthquake and some buildings seeming to be well constructed• As expected, masonry and in particular rubble stone walls performed badly• Aftershocks were continuing to cause problems to these buildings• Schools performed badly, but hope is on the horizon• Event affected poorest communities most heavily (in mountainous regions) – mainly
through the destruction of housing, death due to landslides and lack of roads for relief efforts
• Labour and materials shortages hampering rebuild• Total damages and loss estimated at 7b USD• Insured loss at about 130m USD• Loss of revenue highest in lost tourism and production (to smaller extent)• Convincing donors (donors ensuring) that aid money will be well spent is an important
and ongoing issue.
Thanks to • EEFIT base team Tristan Lloyd and Berenice Chen• EPSRC for funding academic members• Mott McDonald, Arup, AIR Worldwide, AECOM and Guy Carpenter for allowing
industrial partners to attend• UNOCHA for looking after us in Gorkha and helping us gain access to remote sites
esprecially Carlos Geha, Alexandra Lazau-Ratz and Susan Roberts• Corporate Sponsors• https://vimeo.com/130332130