Input Data

3.3.3.1 Data Requirement and Sources

Several types of spatial and non-spatial data from Merapi were collected and used to generate the agent and environment (Table 3.1). The spatial data

mainly comprises the administrative boundaries of Sleman, the volcanic hazard zone, land use, and road network. The non-spatial data comprises microdata from the Indonesian Census of 2010 from IPUMS (Minnesota Population Center, 2015), demography, and population characteristics developed from the survey.

Table 3.1 Dataset list for the model.

Data Source Use

ABM development

Administrative boundary Indonesian Geospatial Agency (BIG)

This data is used to distribute the human agents within the

boundary.

Volcanic hazard zones

(1) National Agency for Disaster Management (BNPB), (2) Based on the evacuation order hazard zones in 2010 (Mei et al., 2013)

Setting up the hazard scenarios and spatial distribution of the eruption impact. Shelter location Geospatial BNPB (BNPB, 2010c; BNPB, 2010a; BNPB, 2010d; BNPB, 2010b), DYMDIS GEGAMA (Budiyono, 2010)

Defining evacuation destination.

Land use Indonesian Geospatial

Agency (BIG)

Defining the mean centre of population distribution (synthetic population generation).

Census microdata

Microdata of the Census of Indonesia 2010 from IPUMS (Minnesota Population Center, 2015)

Defining the sociodemographic characteristic distribution

(synthetic population generation).

Road networks OSM PBF File

(GEOFABRIK, 2016) Evacuation routing

Survey data Survey Formulating the decision making.

Validation

Map of distribution of reluctant people

Evacuation refusal map

(Lavigne et al., 2017) Spatial validation. Series of daily records of

evacuees in 2010 eruption

Local Government of Sleman (Slemankab, 2010)

3.3.3.2 Survey: Design and Data Analysis

1. Questionnaire Development

The questionnaire was developed to gather information regarding the mechanisms used in decision-making and the interaction of people during eruption crises in the Mt. Merapi region. A literature review was conducted to explore the variables that influence decision-making and interaction. Five primary variables were assessed in the questionnaire survey; namely, socio- demographic characteristics, perception of volcanic hazard, decision-making behaviour, interaction during a crisis, and willingness to accept and act on an alert. The question list is developed based on these variables.

The demographic characteristics are used in this research to characterize the agent as well as identify the social vulnerability of the agent. Social vulnerability is defined as "the characteristics of a person or group and their situation that influence their capacity to anticipate, cope with, resist and recover from the impact of a natural hazard" (Blaikie et al., 2014). Vulnerability is multidimensional, and so consists of many variables

(Lummen and Yamada, 2014). Cutter et al. (2003) recognized that the social vulnerability index comprises several indicators: socioeconomic status

(income, political power, prestige), gender, race and ethnicity, age,

commercial and industrial development, unemployment, rural/urban status, residential property type, infrastructure and lifelines, renter, occupation, family structure, education, population growth, availability of medical services, social dependence, and special needs populations. Alcorn et al. (2013) listed the social vulnerability factors, consisting of ethnicity, age, class, wealth, wealth/extractive employment, poverty/unemployment, race, and gender. Letsie (2015) summarized the social vulnerability factors from various studies, mainly comprising income, gender, race/ethnicity, age, unemployment, housing condition, infrastructure, family structure, education, culture, place, population growth, special need, commercial and industrial development, and built environment. Holand et al. (2011) classified the vulnerability indicators as socioeconomic vulnerability and built environment vulnerability. More specific to the evacuation assistant needs, Chakraborty et al. (2005) developed Social Vulnerability for Evacuation Assistance Need (SVEAI), with ten variables from three social characteristics; namely, population and structure, differential access to resources, and population with special evacuation needs. According to Holand et al. (2011), the questionnaire needs to measure socioeconomic vulnerability. Meanwhile, the built environment vulnerability is observed from spatial data. Several

relevant indicators from Letsie (2015) and Chakraborty et al. (2005) are used: income, gender, race/ethnicity, age, unemployment, family structure, education, culture, special need, communication access, and transportation access. The questionnaire is thus used to capture the full range of

demographic characteristics of the people.

Perception, on the other hand, relates to the way in which individuals or communities respond to natural disasters (Rianto, 2009). Risk perception is the estimated probability at which people perceive that hazards will affect them (Lavigne et al., 2008). Perception of risk is developed from several factors: exposure, familiarity, preventability and dread (Rosenbaum and Culshaw, 2003). Exposure, preventability and dread are actually quite complex in nature. They are related to the nature of hazard events and the element at risk. Therefore, to measure the perception of the population, familiarity with the likelihood of an eruption will be used. Table 3.2 lists the questions used to assess the perception of people regarding the risk, based on natural cues. The expected answer to each question (the real risk level) is provided in Table 3.3. The perception (how accurately people perceive the risk) is measured based on how the answer compares to the real risk level (Table 3.4), where the overall score is the average.

Table 3.2 Question list to assess people’s perception of volcanic risk.

Volcanic Activity 1 No Risk It is safe for me to stay 2 Slight Danger but I prefer to stay 3 Moderate Danger May still be safe for

me to stay 3 Severe Danger I have to evacuate 4 Extreme Danger I should not be here You see gas rising from the crater

You feel tremors

You hear/see explosion

Your environment is full of ash You see material in your village collapsing

Table 3.3 Expected answers to the questions in Table 3.2. Volcanic Activity Risk level (Real)

You see gas emitted from the crater 1

You feel tremors 2

You hear/watch explosion 3

Your environment fulfilled by ashes 4

You see material collapse to your village 5

Table 3.4 Matrix for evaluating the accuracy of people’s perceptions. Perceived (P) – Real (R) R1 R2 R3 R4 R5 P1 5 4 3 2 1 P2 4 5 4 3 2 P3 3 4 5 4 3 P4 2 3 4 5 4 P5 1 2 3 4 5

Meanwhile, the decision-making process describes when people start to evacuate. It explores the variability of the population in terms of making decisions during a crisis. The main indicator of this behaviour is the start time, related to the onset of enhanced activity of the volcano. Based on Golledge (1997), decision-making can be classified as disaggregate or aggregate. Aggregate decision-making occurs when the decision is made by a single unit of the population i.e. an individual or household. Meanwhile, an aggregate decision is made by a group within the population i.e. the

community. This questionnaire explores the decision-making process on the basis of the household (disaggregate) level. The questionnaire explores the factors that might motivate or demotivate people in making the decision whether to evacuate.

Interaction during a crisis can take the form of word-of-mouth (WOM) via various media. Word-of-mouth can be analyzed based on the probability that people will forward information to others (Allsop et al., 2007). In this case, data on the probability that people will forward their information about alerts and the impact of this on people’s decisions people is needed. Mathbor (2016) highlighted that social organizations play an important role in

reducing vulnerability. It mainly consists of the social coping mechanism of the family, group or community: resilience, unity and solidarity. Such

was identified from the questionnaire survey. These data are used to estimate the probability that people will pass their information on to others. The interaction behaviour is expressed as a social concern variable in the questionnaire.

2. Field Survey

In order to collect these variables, stratified random sampling was applied. Household member samples, represented as building units, were selected randomly for each building block (dusun). This area segmentation is based on the consideration that each dusun has one village chief who mobilizes people (Rukun Tangga) and, commonly, in the rural areas of Indonesia, has homogenous social characteristics. Twelve villages were selected within a radius of 20km. Several ring buffers with distance ranges of 5 km were created to define the sampling areas, with three villages selected from each range. Furthermore, 10 participants from each village were selected

randomly, resulting in 120 participants in total. 3. Data Analysis

The results of the survey were statistically analysed to develop the

evacuation decision model (see Supplementary MaterialAppendix 3.1). The data from the survey were tabulated and analysed using SPSS. Linear regression was used to analyse the data to generate a formulation of the variable value based on the demographic characteristics (Figure 3.3). The result of the regression analysis is used to develop the driving forces governing the decision to evacuate and to stay. These were also partially used to characterize the agents (the majority of agent characteristics were taken from census microdata).

4. Limitation of the Survey

This survey has limitations regarding uncertainty of participant selection and the possible changes in the perceptions of people regarding the risk. The survey expected to meet the head of the household as a participant.

However, in some cases, the head of household was away for work or other purposes because the survey was conducted during the daytime. In those cases, a member of the household who had the ability to answer the

questions was selected to represent the head of the household. On the other hand, people may also change their perceptions regarding the volcanic risk due to the time lag between the last eruption (2010) and the survey (2016).

3.3.4 Model Design