Post-earthquake assessment of buildings using Mobile Technology and Google Imaginary plus GIS visualization

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1 Post-earthquake assessment of buildings using Mobile Technology and Google Imaginary plus GIS visualization Sujan Raj ADHIKARI 1, Gopi Krishna BASYAL 2, Surya Narayan SHRESTHA 3 and Suman PRADHAN 4 1 Geologist, National Society of Earthquake Technology, Nepal sadhikari@nset.org.np 2 Geographer, National Society of Earthquake Technology, Nepal 3 Deputy Executive Director, National Society of Earthquake Technology, Nepal 4 Program Manager, National Society of Earthquake Technology, Nepal ABSTRACT The aim of this article is to present a computer-aided comprehensive strategy for the detailed damage assessment of the buildings and the optimal prioritization of strengthening and remedial actions that are necessary after a major earthquake event. Based on the visual screening procedures a building inventory was first compiled; then a vulnerability ranking procedure was specifically tailored to the prevailing construction practice implemented into a multi-functional, georeferenced computer tool, that accommodates the management, evaluation, processing and archiving of the data stock gathered during the post-earthquake assessment process, and the visualization of its spatial distribution. The methodology proposed and the computer system developed was then applied to the Municipality of Chautara, Sindhupalchok, Nepal, city which was strongly damaged during the overwhelming 2015 Gorkha earthquake. Keywords: building damage assessment, GIS, mobile data transmission, Gorkha earthquake, Nepal 1. INTRODUCTION Nepal was shaken by magnitude Mw7.8 (ML 7.6, in terms of local magnitude, Department of Mine and Geology (DMG)) Gorkha Earthquake on 25th April 2015 at 11:56 AM local time with the epicenter at Barpak, Gorkha, 80km North West of Kathmandu Valley. This Gorkha Earthquake was followed by thousands of aftershock including M6.6 and M6.7 within 24 hours and Mw 7.3 (ML 6.7, DMG) on 12th May 2015 which caused additional damage and casualties. The spatial distribution of aftershocks occurred before 15 June 2015 is shown in Figure 1. According to official reports the worst affected districts include Sindulpalchowk, Kavre, Nuwakot, Rasuwa, Dolakha in the Central Region and Kaski, Gorkha, Lamjung in the Western Region. The impacts caused by this event included 8,969 people killed, 22,321 injured and, many more displaced (MOHA, 2015). In addition, significant damage to buildings, infrastructure and other critical services were well observed.

2 October 2015, Kathmandu, Nepal Figure 1 Spatial distribution of Aftershocks Geoinformation technologies offer an opportunity to enhance real time situation management, disaster response and subsequent post event (Gusella. L. et. al). To help improve the usefulness of geoinformation in a post disaster context, information should be freely available, up-to-date and provide in georefrenced format. Data requirements have traditionally been met through ground based damage survey during the days and weeks following the events. However the integrations of remote sensing (google earth imaginary) data and georefrenced damage information collected in the field can effectively streamline, accelerate and increase the volume and diversity of data captured during post disaster reconnaissance. Remote sensing (Google Imaginary) plays a valuable role to play when integrated within and used in conjunction with mobile mapping technology which enable the collection of digital data of each house in the field. This paper aims to give detailed explanation of Chautara Municiplity of Sindhupalchok District which have 9 wards, how technology (mobile and Google earth) inspired and alliance were used to speedily assess the amount of damage caused by Gorkha earthquake. In less than a minute, devastating earthquake demolished approximately 90 percent of the buildings in Sindhupalchok killing 3,557 people; numerous injuries; and leaving 63,885 homeless (drrrportal, Nepal). Almost from the very onset of the disaster, high-resolution satellite imagery was available through Google earth to provide the first insight of the devastation caused by Gorkha earthquake. Google Earth imaginary can form a base layer for buildings within the system, guiding the team to recognize each damaged building and proving the direction-finding support. The whole system is integrated with mobile mapping ground based perspective to develop and validate Google GIS imaginary based building damage scales, and to access the accuracy of damage assessment results. New Technologies for Urban Safety of Mega Cities in Asia

3 2. PAST WORKS The frequency and magnitude of natural hazard and its occurrence is growing rapidly in the country. The impact of disasters even small scale has left negative impacts at local level. Municipalities have been spending significant amount of money for recovering those losses from disasters. Advanced disaster management technology could provide a critical support system for emergency authorities during crises. Such a technology can also provide important inputs for any disaster management plan of action in modern times (Mileti, 1999). There are growing recognition that a mobile disaster management system could help minimizing the fatalities of human lives when natural disasters occur. Because of this recognition, countries such as Australia, Czech Republic, France, England, Hong Kong, Japan, Singapore, and others, have increased their efforts in developing disaster management applications which use mobile technology to enhance their response capabilities during a disaster (Cimellaro et al 2014). For correct decision-making at any stage of natural disasters, from prediction to reconstruction and rehabilitation, a considerable amount of data and information is necessary. The most important procedures relating information from disasters are monitoring, recording, processing, sharing, and dissemination. Experience from Italy and Japan have proved that information technology simplifies the receiving, classifying, analyzing, and dissemination of information for appropriate decision-making (Sextos, A 2008). A critical component of any successful rescue operation is time. Prior knowledge of the precise location of landmarks, streets, buildings, emergency service resources, and disaster relief sites saves time and saves lives. Literature shows that mobile-based information systems can be a greatest key to benefit responders in different ways. Implementation of new information technologies in emergency response can potentially improve communication and coordination (Comfort, 1999; Comfort and Kapucu, 2006). A more robust information network with greater distribution will further improve communication and coordination in major disasters (Comfort and Kapucu, 2006; Graber, 2003). The possibility of using mobile technologies and the Web to build and substitute response systems would aid communities disaster management cycle, uploading and distributing information, and coordinating the responses. 3. METHODOLOGY Traditional method of damage assessment comprise of walking survey, where damage indicators together with the overall damage state, are logged on damage assessment form in paper format. But for this study, questionnaire Survey of each buildings is developed in odk android Mobile environment following documents of Guideline on Seismic Vulnerability Evaluation Guideline for Private and Public Buildings which was prepared by NSET, The study area was divided into a grid (figure 2) of 200*200m square cells field paper which consists base map of Google Imaginary. Surveyor locate each building and Post-earthquake assessment of buildings using Mobile Technology and Google Imaginary plus GIS visualization

October 2015, Kathmandu, Nepal provide the ID of every building in field paper. And using mobile application they input the damage information for buildings.

Section A contains building identification data (id, city, address, ownership, no of resident etc.

4 October 2015, Kathmandu, Nepal provide the ID of every building in field paper. And using mobile application they input the damage information for buildings. Figure 2 Grids of the Chautara Municipality Mobile inspection form consists of five Section (figure 2). Section A contains building identification data (id, city, address, ownership, no of resident etc.), Section B contains building technical characteristic (no of stories, age of building, primary occupancy etc.), Section C contains geotechnical hazard, Section D contains data related to the structural type and Section E contains Damage grade, recommendations and building Photographs. Figure 3 Digitization of the building in the google Earth New Technologies for Urban Safety of Mega Cities in Asia

5 After completing of Buildings survey in one girds, surveyors handover the paper to the GIS mapper so that they digitize each building as of filed paper in the Google earth environment (figure 3). In the intranet server, all the information collected form each Mobile device is uploaded and digital database is prepared. Later on, all information of the building that are collected from the mobile devices were join with each building digitized by GIS mapper in GIS Environment for the visualization of the assessment results using QGIS software. Reason for choosing Google Earth as the platform for the image analysis is because it is freely available across the globe and people are familiar with it and have readily available pre-event imagery archive for selected area in Nepal and can incorporate imagery captured at multiple dates. 4. RESULTS It is observed that Chutara Municipality have 83% of Stone in Mud type building where only 14% RCFrame structure considering Figure 4a and 4b. Figure 4 a Building Typology vs Number of Buildings Figure 4b Map Showing Construction type Post-earthquake assessment of buildings using Mobile Technology and Google Imaginary plus GIS visualization

6 October 2015, Kathmandu, Nepal Also, 70% of buildings have been categorized under Grade5 whereas 15% falls under Grade4.Also, Grade1, Grade2 and Grade3 corresponds to 5%, 8%, 2% of sum chronologically referring to figure 5a and 5b Figure 5a Building Typology vs Damage Grade. Figure 5b Map showing Damage Grade New Technologies for Urban Safety of Mega Cities in Asia

7 Table 1: Recommendation for different ward WARD Recommendation Total None Repair Retrofit Demolish Further Evaluation Grand Total Figure 6 Map showing Recommendation type With regard to the above assessment and analysis Table 1 and Figure 6, 83% of totally surveyed buildings are suggested to be demolished. Repairing is most for 13% of left part. Only 3% of buildings are recommended to get retrofitted. 5. CONCLUSION Natural Disasters are not certain, could occur anytime and seriously disrupts the functioning of a community causing huge losses. However, during the time of crisis the collection and dissemination of damaged data are crucial. This study positively support the government to developed reconstruction strategy plan. Apart from it, this study will monitor Chautara Municipality to differentiate the building which are possible to repair/ retrofit and which needs demolition. Hence, GIS tools if properly utilized, saves time, labor and improve efficiency of work. Prompt data collection and its analysis results over time could prepare agencies to better response for future disasters. Thus, paper Post-earthquake assessment of buildings using Mobile Technology and Google Imaginary plus GIS visualization

8 October 2015, Kathmandu, Nepal illustrates the utilization of technologies (mobile and google earth) to collect postdisaster damage information within short span of time. ACKNOWLEDGEMENTS The authors would like to express heartily gratitude all the members of study team, without whose support, the study would not have been successful. REFERENCES Arcidiacono V and Cimellaro GP (2013), Damage Report with Smartphones during Emilia Earthquake, 2012, 4th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN2013), Kos Island Greece, June, Comfort Louise K (1999), Shared risk: Complex Systems in Seismic Response, Emerald Group Publishing Limited (August 1, 1999) Mileti Dennis (1999), Disasters by Design: A Reassessment of Natural Hazards in the United States, Joseph Henry Press (May 18, 1999). New Technologies for Urban Safety of Mega Cities in Asia

Building Sustainable and Resilient Communities

2015/SOM1/EPWG/032 Agenda Item: 8.6 Building Sustainable and Resilient Communities Purpose: Information Submitted by: China 7 th Emergency Preparedness Working Group Meeting Subic, Philippines 28-29 January