Use of Geospatial Techniques in Post Earthquake Disaster Mitigation

“Where the mind is without fear, the head is held high.”
Everyone would love to agree with this thought of Rabindranath Tagore as expressed in one of his famous poems. If some phenomenon, which has the potential to take our lives, leave alone property, can take place at any point of time around us, then we can do nothing, but be scared about it. Natural Disasters like earthquakes, volcanoes, tsunamis and cyclones are phenomenon which has terrorized human beings right from the day it first appeared on earth. With all the science and technology around us nowadays, the question is: “Can we never get rid of these terrifying phenomenons?” Well the answer is that we may not be in a position to stop these phenomenons as of now with all our science and technology. But we can surely do something to minimize the destruction of life and property.

Geospatial techniques, with its constituents Remote Sensing, Geographical Information System, Geodesy, Geophysics, etc may help us in our endeavor to minimize the destruction caused by these phenomenon. The use of geospatial techniques in post earthquake disaster mitigation can be divided into two parts: 1. Short term response, recovery and rehabilitation, and 2. Long term response, recovery and rehabilitation. The focus of this article will be primarily on short term response, recovery and rehabilitation.

Every time an earthquake occurs in our country, there is huge loss of life and property. This loss is aggravated further due to delay in response, rescue and relief operations. Let us see for ourselves some of the shortcomings of post earthquake disaster mitigation without the use of geospatial techniques as it took place in Bhuj.

At 8.50 am on Friday, 26th January, 2001, as school children started celebrating the Republic day, a series of powerful earthquakes struck Gujarat, peaking at a massive 7.9 on the Richter scale, with its epicenter located at 30 km north of the town of Bhuj leaving approximately 20000 people dead and about 167,000 people injured. It was estimated that nearly 1 million homes were damaged. Such widespread damage could have been prevented by the use of geospatial techniques and better preparedness.

The picture shows the devastation caused by Bhuj earthquake.

The authorities did not even have a proper estimate of the amount of relief required in cash and kind. An arbitrary exorbitant amount was asked from the consolidated fund of India and also from the World Bank, which was actually not required. The following data shows that we had already received more relief than required.
 

Updated summary table	Appeal target	Total Received	Unit	Total Dispatched from 5th to 16th May	Total dispatched	Stock
Blankets	210000	230278	Pcs	0	228724	1554
Tarpaulins	118000	110323	Pcs	1594	110209	114
Tents	34038	32059	Pcs	1463	32000	59
Kitchen sets	60000	59956	Sets	4563	52557	7399
Water Containers	63000	61469	Pcs	12690	61469	0
Cholera kits		8	Kit	0	2	6

The administration received 25.6 million in cash, kind and services including relief supplies and emergency response units, but it could reach only 12 villages across four district of Gujarat, whereas other affected areas were left aloof. Another fear rose that partially damaged buildings could collapse from heavy rains and the land which was made uneven during the earthquake could trigger mud slides. Even then, no action was taken for a number of days.

Now let us see how Geospatial techniques can help overcome these and other numerous bottlenecks in the Post Earthquake Disaster Mitigation process and save the lives of thousands.

A scientific approach towards immediate mitigation of earthquake disasters with the help of geospatial techniques will involve development of an effective Decision Support System. An effective Decision Support System will involve the following components.

Overlaying of the different maps and data is done as shown below. Also the different attribute data are stored in relational databases as shown below for quick and efficient retrieval of data for taking efficient decisions.

1.Hazard, Vulnerability, Risk and Capacity (HVRC) assessment:

Hazard: Hazard analysis is done to determine the type of disaster that may take place in a particular place. Geographical Information Systems use the result of this analysis to prepare the preparedness plan. It consists of mapping fault lines, assessing geomorphology of the area, topology, groundwater system, drainage and land use.

Vulnerability: Vulnerability assessment is done to form an idea about the type and extent of the damage which is expected to occur in the event of an earthquake. This assessment is primarily based on ground data. The output of this assessment is used as input for the Geographical Information System used in the mitigation process. Vulnerability assessment consist of preparing the census of the area, administrative database about manmade structures like buildings, dams, etc, identification of rescue areas such as schools, open areas, health centres, etc and rescue routes such as bridges, road, railway lines, airports, etc.

Risk: Risk assessment is done to know how much an area is prone to a particular disaster. It consists of calculating the frequency of seismic activities on the basis of the past records, the intensity of the hazardous events, estimation of secondary disaster risks such as dam bursts, fires, risk of petroleum pipe lines bursting, mud slides etc.

Capacity: Capacity assessment is done to keep a track of the basic infrastructure that can be used in the event of a disaster. It consist of mapping the availability of the rescue areas, studying the feasibility of the relief and response centres, checking whether there are adequate number of rescue and response centres available, checking the inventory of relief equipments.

2. Detection System: Detection systems used are mainly of two types. They are: 1. Remote Detection System: It helps us in getting a generic view of the affected areas on a large scale, and 2. Ground based detection system: It helps us in overcoming the limitations of resolution of remote sensing equipments. It help us in getting the real picture of the damage, eg: Number of people trapped inside a collapsed building which cannot be judged by remote sensors.

3.Scenario study: As soon as an earthquake strikes, the first thing that attracts attention of the administration is the knowledge of the extent and distribution of destruction. This is done with the help of satellite images. For instance, IKONOS or LIDAR images or aerial photographs can be used to analyze the spatial distribution of damages an divide the affected area into zones based on the amount of the damage to the buildings. Remote sensing data can be further used to analyze the damage to key points like hospitals, bridges, roads, etc, mapping the alternative rescue and relief routes and mapping the open spaces, etc for setting up of relief camps, cremation and burial grounds.

4. Preparation of ICS systems: Setting up of an effective incident command system is of top most priority as this is the main control system for the proper mitigation process. It consists of determining the type and urgency of services needed on the basis of zonation maps prepared during scenario study, demographic maps available and the type of settlements. Proper allocation of the limited resources to the affected areas to be decided on the basis of priority, which is one of the primary tasks of an ICS system. Establishing a framework of communication and coordination between various response and services department is possible with the help of ICS system as each such department gets to know their exact tasks. GIS supported ICS systems help in getting a realistic and fairly accurate analysis of cost of damage from economic point of view and determining the amount of funds required for relief. Proper monitoring of the expenditure also help in determining the amount required for rebuilding purpose. Determining the sequence of rescue functions is also a job of ICS systems.

5.Response monitoring: Response functions must be carefully monitored so that there is a proper distribution of the relief materials. Use of satellite images in this phase helps in the dynamic allocation of the limited resources available in the hands of the ICS system or the administration.

6.Option analysis: Proper weighing of the options is necessary to avoid confusion and ensure speedy rescue and relief operations. As seen during the Bhuj earthquake, many of the roads became damaged and were rendered useless. Proper mapping of alternate routes with the help of satellite data could have saved many lives. Thus weighing of the options for site selection to set up relief camps or alternate routes as discussed above is a very important part of Post earthquake disaster mitigation. Proper analysis of the capacity of the administration to deal with the mitigation process and determining whether the option of acquiring help from outside is required at all, is a very important task of the administration during this period, as this could have prevented the situation that Bhuj faced with redundant relief material. It must also be remembered at this stage that any external help take time to reach the affected areas.

7.Long term damage assessment: Long term damage assessment is done to know the amount of damage occurred in the affected area and it is this element that lays down the foundation of the rehabilitation plan. It consists of estimating the cost of damage and rebuilding the area side by side. Assessing the economic loss, building empirical benefit cost models for construction of buildings in future. It also assesses the loss to life. The analysis is also carried out to know the reasons of damage whether the area was prepared to face the disaster, whether the buildings were planned according to the building byelaws etc.

8.Processing the feedbacks: Critical evaluation of the causes of damage, suggesting ways of better preparedness for future earthquakes can help save lots of life in future. Before the earthquake took place at Bhuj, stones or fly ash bricks were the primary building material. After the bitter experience, special types of light weight bricks are used.

Geospatial techniques have been found to save 70% of the total number of lives lost in the event of an earthquake. Most lives are lost due to lack of preparedness among the people. Let us not repeat another Bhuj. When an earthquake strike U.S, very few lives are lost, leave alone property. With all our technological progress, can we not prevent a Bhuj or a Latur? Only then will the prayers of Rabindranath be truly answered which he mentioned through these famous lines:

“Into that heaven of freedom, My father, Let my country awake.”