Disasters, whether natural, man-made, or technological, all have the potential to affect psychological health. Many effects are common to all types of disaster. However, research findings from specific disasters, such as earthquakes and floods, show that each can also have unique consequences for the mental health of survivors.
On average, 17 major earthquakes (magnitude 7.0-7.9) and 1 earthquake of magnitude 8.0 or above occur around the world each year (1). Earthquakes, compared to other natural disasters, carry the highest risk of severe damage and injury. Many factors contribute to the level of damage caused, including how populated the affected area is. Also, rather than being a circumscribed event with a defined endpoint, earthquakes tend to produce a series of events that continue to affect people's lives over a prolonged period. Persistent or recurring disruptions from the earthquake substantially contribute to continued mental health problems.
Some research has found that general distress levels following an earthquake appear to return to normal after about 12 months, but posttraumatic stress reactions do not fade until 18 months after the earthquake (2). The prevalence of PTSD varies widely in earthquake survivors (3). In adults, percentages as high as 92% have been seen (4), while in children, as many as 95% (5) and as few as 4.5% (6) have been found to have PTSD after an earthquake. This variability is due in large part to differing levels of trauma exposure and proximity to the epicenter of the earthquake. In addition, methodology differs among studies, and cultural or socioeconomic factors may also affect the types and severity of symptoms experienced by survivors.
1993 Turkey Earthquake. Research found that nearly all of the survivors reported emotional reactions. Fear and panic were the most common effects. About a quarter experienced worry about family members, feelings that life was meaningless, and sadness about the dead and injured. The majority of the survivors stated that these emotional problems still distressed them after 16 months. As is true after most disasters, females were particularly likely to be distressed (7).
1988 China Earthquake. Following the Yunnan earthquake in China, psychiatric morbidity rates doubled in the most severely affected regions. These rates were seen six months after the disaster. Of note, in this rural Chinese population, much of the posttraumatic morbidity expressed itself as somatic symptoms (8).
1995 Japan Earthquake. An eyewitness to the Kobe earthquake in Japan (9) reported, "Three years after the earthquake, victims are still suffering from psychological difficulties resulting mostly from living isolated lives in temporary housing."
Floods, tornadoes, and hurricanes
Around the world, floods make up almost a third of the disasters that occur, greater than any other disaster type (10). In the US, floods lead to more than three-fourths of declared Federal disasters (11) and kill 140 people each year (12). Many floods are caused by tropical storms or hurricanes. In addition, catastrophic flooding can be caused by a tsunami or giant ocean wave.
Hurricanes and tornados also bring high winds that can cause great damage. On average five hurricanes strike the US mainland every three years, with two of those strikes being major storms (13). An average of 20 violent tornados and 1 extremely violent tornado can be expected in the US each year (14).
Disasters that involve flooding or high winds tend to cause a range of effects depending on their severity (15-16). After disasters of this type, the impairment of most survivors is moderate. Effects may be prolonged but do not usually meet criteria for a mental disorder. However, in a significant minority of research studies on disasters of water and wind, at least 25% of the survivors had symptoms of a diagnosable disorder. Symptoms usually peak during the first year, and in the vast majority of cases, survivors get better with time after the disaster.
The research findings presented below serve as examples of the impact that major disasters of water and wind can have on the mental health of survivors.
2004 Tsunami. On December 26, 2004, a massive tsunami hit the shorelines of Indonesia, Sri Lanka, India, Thailand, and the Maldives. The tsunami was triggered by an undersea earthquake (magnitude 9.3). It is estimated that at least 280,000 people died, and at least five million people were affected (17). Research across the countries affected by the tsunami found high levels of PTSD, for example, 15 months after the tsunami, prevalence was 52% in Sri Lanka (14). In more than one study, researchers found that loss of work and income were related to mental health symptoms, and symptoms were higher among females (18-21). In Thailand, relatives of tsunami victims that were never found worried that the spirits of their family members were not at rest (21). Because of cultural beliefs that burial rituals are needed, post disaster distress may have been exacerbated.
Hurricane Katrina. In August of 2005, Hurricane Katrina devastated the US Gulf Coast. Unlike other disaster research which tends to show decreases in the prevalence of mental disorders over time after a disaster, following Hurricane Katrina, an increase was found, (22). Nearly two years after Hurricane Katrina, there was still a high rate of hurricane-related mental health problems, including PTSD, in residents of the affected area. Research pointed to unresolved hurricane-related stress as a major factor in those problems. In African American and Vietnamese survivors of the hurricane, researchers found that financial strain had an impact on PTSD symptoms several months after the hurricane (23-24). Displacement may also have contributed to distress. One study examining PTSD symptoms in evacuees from New Orleans who had settled in Oklahoma, found that, almost a year and a half after Katrina, both adult and adolescent evacuees had higher levels of PTSD symptoms than Oklahoma residents who were not evacuees (25).
Hurricanes Andrew and Paulina. Researchers compared PTSD symptoms in survivors of Hurricanes Paulina (Mexico) and Andrew (United States), six months after the disasters. In both groups, the symptoms of PTSD were related to how severe the trauma exposure was for the survivors. Some differences were seen in the types of symptoms shown by the two groups. For example, the Mexican survivors showed more unwanted thoughts and memories of the trauma and avoidance of trauma reminders. The American hurricane survivors showed more PTSD arousal symptoms (26).
1999 Mexico flood. Research conducted across several disaster sites affected by this flooding found that six months after the flood, depression and PTSD were both high. Levels declined over time but remained elevated two years post flood. Survivors with more exposure to the disaster reported higher rates of physical health symptoms as well as higher prevalence of PTSD. Distress may have been elevated because women who were displaced or forced to leave home had weaker social support networks (27-29). Naturally occurring social resources are particularly vital for disaster victims (15, 16).
Wildfires have become less frequent but more severe over the last 200 years (30). Research has looked at the effects of major fires that damaged homes and neighborhoods in a number of locations including the United States, Europe, and Australia. These studies have documented the mental health effects of wildfires on both children and adults. Human-caused or technological fire disasters can have severe effects as well.
2003 California Firestorm. In the fall of 2003 wildfires destroyed a large area in Southern California. An estimated 100,000 people were evacuated. Data collected from survivors at nearby disaster relief facilities showed that over two-thirds had feared for their life or that of a loved one. When these survivors were screened three months later, one-third screened positive for depression and almost one-fourth screened positive for PTSD (31).
1983 Australian Bushfire. Researchers documented severe effects of the Ash Wednesday Bushfire on schoolchildren in Australia. They found that the negative effects did not decrease in the 1.5 years after the disaster (32). Another large study of over 1500 Bushfire survivors found that in the 12 months after the fire, stress-related health problems - including mental illness - increased, as compared to health conditions not related to stress (33).
Enschede, Netherlands, Explosion. At least 30% of those affected by the explosion at a fireworks storage depot experienced serious physical and mental health problems two to three weeks after the explosion (34). These effects continued over time. Later research found higher use of mental health services among Enschede residents in the four years following the disaster, as compared to residents of a different Dutch town (35).
Although research on disasters shows many common effects across disaster types, each disaster is unique, and a number of factors may determine a given disaster's effects on survivors. Continuing aftershocks following an earthquake, loss of income or employment, life threat, or cultural beliefs are just a few of the factors that can contribute to mental and physical health problems in disaster survivors.
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