[HCG24-04] Do the Rich Suffer Less Damage from a Natural Hazard? A Case of the 2015 Nepal Earthquake
キーワード：地震、経済学、家計の豊かさ、ネパール、PGA
Introduction
Practitioners and academics have reached a consensus that there are no natural disasters. Studies show that natural disasters are jointly caused by natural hazards and social problems, such as poverty and political dysfunctions. Several studies also show that preparedness against natural hazards increases with income levels. This association between poverty and preparedness against natural hazards may raise a serious issue in empirical analyses. The level of disaster damage is not only ascertained by the intensity of natural disasters but also by the characteristics of a household (HH).
However, taking into account the data at the micro level, since few studies statistically measured the association between social status (including the income level) and the damages from natural hazards, the effect of income on the level of disaster damage has not been accurately ascertained. This study tries to extend existing knowledge to clarify the impact of wealth on the damage from natural disasters.
Materials and methods
This study utilizes the index of the damages that HHs suffered during the 2015 earthquake (EQ) in Nepal. Nepal is located on a highly active seismic zone, and it was hit by a 7.8 magnitude earthquake on April 25, 2015. After the EQ, the Nepal government employed many engineers and assessed the damage on the private buildings, mainly private houses, in all the EQ hit districts. The Nepal Reconstruction Authority (NRA) has been entrusted with this damage data; by utilizing NRA’s house damage data, this study provides evidence of the endogeneity of EQ damages in the following manner.
The study measures the gap between the magnitude of the EQ and the damage to the house; this gap should be zero if there are no impacts of HH characteristics. A correlation between HH characteristics, such as HH wealth and materials of buildings, and the damage level of the house would increase or decrease the damage caused depending on HH income level, even when the intensity of EQ is controlled. Subsequently, the study employs the peak ground acceleration (PGA) and the topographic slope using geographic information systems (GIS) to measure the aforementioned relationship. PGA is considered a major indicator for characterizing seismic hazard in engineering analysis.
To identify the wealthy HHs’ endogenous factors of the damage grade, we regress the damage grade on PGA, building materials (based on the building’s strength), and HH characteristics.
Results
NRA data show that the HH wealth has a certain correlation with the damage grade of EQ over a wide area. However, the results of the estimation using building materials and detailed HH data do not show a clear evidence that the HH wealth and damage of the EQ are correlated. Moreover, higher buildings were more damaged from the EQ. This result indicates that richer HH may not have taken care of the natural hazards in the study site and suffered the risk from the EQ. A significant increase in cash income through remittances did not reduce the damages to houses. Our results rather suggest that poor households suffered less from the 2015 EQ thanks to the “light” construction materials of their houses, such as mud and straw. At this income level, an increase in income does not work as a strong alleviator of natural disaster.
Practitioners and academics have reached a consensus that there are no natural disasters. Studies show that natural disasters are jointly caused by natural hazards and social problems, such as poverty and political dysfunctions. Several studies also show that preparedness against natural hazards increases with income levels. This association between poverty and preparedness against natural hazards may raise a serious issue in empirical analyses. The level of disaster damage is not only ascertained by the intensity of natural disasters but also by the characteristics of a household (HH).
However, taking into account the data at the micro level, since few studies statistically measured the association between social status (including the income level) and the damages from natural hazards, the effect of income on the level of disaster damage has not been accurately ascertained. This study tries to extend existing knowledge to clarify the impact of wealth on the damage from natural disasters.
Materials and methods
This study utilizes the index of the damages that HHs suffered during the 2015 earthquake (EQ) in Nepal. Nepal is located on a highly active seismic zone, and it was hit by a 7.8 magnitude earthquake on April 25, 2015. After the EQ, the Nepal government employed many engineers and assessed the damage on the private buildings, mainly private houses, in all the EQ hit districts. The Nepal Reconstruction Authority (NRA) has been entrusted with this damage data; by utilizing NRA’s house damage data, this study provides evidence of the endogeneity of EQ damages in the following manner.
The study measures the gap between the magnitude of the EQ and the damage to the house; this gap should be zero if there are no impacts of HH characteristics. A correlation between HH characteristics, such as HH wealth and materials of buildings, and the damage level of the house would increase or decrease the damage caused depending on HH income level, even when the intensity of EQ is controlled. Subsequently, the study employs the peak ground acceleration (PGA) and the topographic slope using geographic information systems (GIS) to measure the aforementioned relationship. PGA is considered a major indicator for characterizing seismic hazard in engineering analysis.
To identify the wealthy HHs’ endogenous factors of the damage grade, we regress the damage grade on PGA, building materials (based on the building’s strength), and HH characteristics.
Results
NRA data show that the HH wealth has a certain correlation with the damage grade of EQ over a wide area. However, the results of the estimation using building materials and detailed HH data do not show a clear evidence that the HH wealth and damage of the EQ are correlated. Moreover, higher buildings were more damaged from the EQ. This result indicates that richer HH may not have taken care of the natural hazards in the study site and suffered the risk from the EQ. A significant increase in cash income through remittances did not reduce the damages to houses. Our results rather suggest that poor households suffered less from the 2015 EQ thanks to the “light” construction materials of their houses, such as mud and straw. At this income level, an increase in income does not work as a strong alleviator of natural disaster.