Ratio of the Dead to Wounded (D/W) Indicators and Associated Factors in Major Earthquakes of America from 1960 to 2011

Table 5

Results and interpretation of the multiple linear regression of the of death toll, number of wounded people, and D/W indexes.

(a)

	Neperian logarithm of number of deaths (D)			Neperian logarithm of number of the wounded (W)			Neperian logarithm of D/W
	Coef.		Signif.	Coefficient		Signif.	Coef.		Signif.
Constant	−2.659	−0.891	0.376	1.000	0.374	0.710	40.706	2.088	0.040
Population density	0.0015	2.901	0.005	0.0011	2.272	0.026
Earthquake magnitude (Richter degrees)	0.951	2.186	0.032	0.765	1.965	0.053
Time (18:00–06:00)	−2.156	−3.243	0.002	−2.047	−3.437	0.001
South America subregion	0.903	0.254	0.800	−1.729	−0.540	0.591
Population density × South America subregion	0.0006	0.280	0.781	0.0014	0.745	0.459
Richter degree × South America subregion	−0.084	−0.164	0.871	0.241	0.521	0.604
Time (18:00–06:00) × South America subregion	2.194	2.422	0.018	1.953	2.386	0.020
Human Development Index							−5.164	−2.231	0.029

(b)

Indicator	Subregion	Variable	Exponential	Relative variation	Interpretation
Deaths (D)		Population density		0.0015	For every unit of increase in the population density, death toll would be increased 0.15%
	Central America	Magnitude (Richter degrees)		1.5883	For every Richter degree increased, death toll would be increased 158%. The number of deaths would be more than double.
		Time (18:00–06:00)		−0.8842	When earthquakes took place at night (18:00–06:00) death toll would be reduced in 88%.
		Densidad Poblacional		0.0021	For every unit of increase in the population density, death toll would be increased in 0.21%.
	South America	Magnitude (Richter degrees)		1.3787	For every Richter degree increased, death toll would be increased in 137%. The number of deaths would be more than double.
		Time (18:00–06:00)		0.0039	When earthquakes took place at night (18:00–06:00) death toll would be increased in 0.39%.
The wounded (W)		Population density		0.0011	For every unit of increase in the population density, the number of the wounded would be increased in 0.11%
	Central America	Magnitude (Richter degrees)		1.1490	For every Richter degree increased the number of wounded people would be increased in 114% (more than double).
		Time (18:00–06:00)		−0.8709	When earthquakes took place at night (18:00–06:00) the number of wounded people would be reduced in 87.09%.
		Population density		0.0024	For every unit of increase in the population density, the number of wounded people would be increased 0.24%
	South America	Magnitude (Richter degrees)		1.7348	For every Richter degree increased, the number of wounded people would be increased 173% (more than three times).
		Time (18:00–06:00)		−0.0896	When earthquakes took place at night (18:00–06:00) the number of wounded people would be reduced in 8.96%.
D/W	Central and South America	Human Development Index		−0.0503	For every 0.01 of increase in the IDH, the D/W index would be reduced in 5.03%.