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