Earthquake




Description of event


Earthquakes are among the most devastating natural disasters. In many regions of the United States imperceptible earthquakes occur frequently. Historically, massive earthquakes have led to some of the most devastating loss of life, limb, and physical infrastructure and have had an overwhelming economic impact on affected communities. When earthquakes occur in oceans or seas they have the potential to cause a large displacement of water, which may trigger a series of giant waves known as a tsunami . Every year there are approximately 500,000 earthquakes worldwide, of which only approximately 20% are perceptible. The potential for disaster exists when an earthquake or subsequent tsunami occurs in a heavily populated area. Although earthquake magnitude plays an important role in the resulting damage, it is not the only factor. The 2010 Haiti Earthquake measured 7.0 on the Richter scale and caused more than 200,000 deaths and thousands of injuries. The 2011 Japan Earthquake measured 9.0 on the Richter scale and caused a tsunami which together caused more than 12,000 deaths and displaced tens of thousands more.


There are critical factors at play other than just magnitude, such as earthquake depth, proximity of the epicenter to population centers, and construction and building codes. The exact mechanism of an earthquake is still largely unknown, but there is the “elastic-rebound theory,” which describes the process that creates the energy release of the earthquake. According to this theory, the tectonic plates of the Earth’s crust are in constant motion and slip along each other tangentially. At the boundary between plates, called faults , friction causes the plates to adhere to each other, while the natural movement of the plates creates strain on this interlocked area. The plates then suddenly and violently move laterally with respect to each other, releasing the potential energy stored at the interface, known as an earthquake hypocenter . This is the place from which the seismic waves are generated that radiate out in all directions. The epicenter of the earthquake is the location on the Earth’s surface directly above the underground hypocenter.


There are two commonly used scales to describe the strength of an earthquake: the Richter scale and the moment magnitude scale (MMS). Both scales range from 0 to 10 and are logarithmic. Earthquakes with magnitudes 6.0 or greater are generally considered significant events and have the potential to cause widespread damage. Geographically the Asian Pacific Rim (from Japan to Indonesia), also known as the Ring of Fire, is the most seismically active area in the world.




Pre-Incident actions


Pre-incident actions in earthquake-prone regions fall into two categories. The first focuses on structural preparations and engineering and design issues intended to strengthen and improve buildings to decrease the likelihood of massive destruction in the face of an earthquake event. These engineering decisions may also focus on the positioning, strengthening, and layout of utility pipes, roadways, and power plants and the relative proximity of potentially dangerous structures, such as factories producing or storing toxic materials and fuel storage facilities, to fault lines and potential earthquake epicenters.


The second set of pre-incident actions for a country with populous regions and cities in the area of large earthquake faults is the development and implementation of a disaster response plan that should include training medical providers and stockpiling equipment to facilitate rapid action in the event of an earthquake.


Most earthquakes strike with little or no warning, and they can occur at any time. Despite constant monitoring of seismic and geologic activity, the ability to predict or detect a significant earthquake in time to mitigate its effects on the community is limited. Improvements in our ability to predict the timing and location of earthquakes, thereby mitigating their impact and preventing loss of life, are continuing and will hopefully play a bigger role in future preparedness. At this moment, however, educating the community, updating building codes, and improving land-use legislation remains the most viable way to mitigate the impact of earthquakes.




Post-Incident actions


One of the most important concepts in disaster response today is that of command and control. There must be a central authority that oversees the disaster response and controls the overall operations, communications, logistics, requests for and distribution of resources, distribution of information, and allocation of search and rescue teams. Temporary health care facilities may need to be constructed and medical and surgical equipment, primary care and subspecialty health care physicians, and other health care workers allocated. This central authority is also responsible for the control, preparation, and distribution of other vital public health elements of the relief efforts, including sanitation, water, shelter, food, clothing, and psychosocial support. Large-scale international disaster responses are well intentioned and somewhat successful in providing lifesaving interventions; nevertheless, they are often inefficient, disorganized, and resource intensive. One problem that responders sometimes encounter is that many of the teams from different countries do not share a common language or system in their approach to the response. They may have different equipment and drugs that cannot be shared across systems and are often unknown to health care practitioners in the host country. This lack of coordination can lead to extensive duplication of some services and the lack of other services completely. Disaster responders from different countries are sometimes reluctant to submit to a central command and control or Incident Command System that is being directed by administrative personnel from a country other than their own. Following the response period a new stage called the resilience period has been recognized, which builds the capacity of a system to absorb future events and maintain civil functions and minimize loss of life and property. This stage takes a long time between onset of the disaster and something close to full recovery.




Medical Treatment of Casualties


Demand for health care is greatest in the period immediately after the earthquake, with studies showing peaks between 12 hours and 3 days after the event. There are two studies from Japan and Taiwan suggesting that serious injuries are most common among the very young and elderly. , Those studies also suggest that people with preexisting disabilities are at high risk for injury, due to their inability to quickly flee the collapsing structures or to free themselves effectively. Another study following the Taiwan earthquake indicates that casualties are higher in areas close to the earthquake epicenter with fewer physicians and hospitals. If local hospitals are still operational after an earthquake, emergency departments are likely to have a surge of patients within the first 24 to 48 hours after the event. Data from the 1999 Marmara, Turkey, Earthquake found that 645 patients were seen at area hospitals for earthquake-related trauma in the 50 days following the disaster, and a total of 271 (42%) were seen in the first 24 hours.


Care for casualties in the immediate aftermath of an earthquake is typically focused on orthopedic and soft tissue trauma, including management of fractures. Due to the prevalence of head injuries requiring surgical procedures, surgeons and anesthesiologists are important components of the early medical response. In addition, deep sedation and pain management with narcotic medication are important in treating earthquake injuries.


In the Armenian Earthquake of 1988 the acute injuries, as clearly witnessed in the cities of northern Armenia, were caused by collapsing buildings, falling rubble, fire, and dust inhalation. Most people caught in collapsing buildings due to earthquakes, especially structures greater than two stories, are killed instantly or trapped in pockets. Some of those trapped have body parts pinned under extremely heavy loads, timbers, or stone. Even when rescued, they will often have crush syndrome and acute renal failure. Others are caught up in the flash fires that accompany the rupture of natural gas pipes and suffer extensive body burns or smoke inhalation, leading to severe morbidity and mortality. A third group of patients suffers acute and chronic respiratory disease from the inhalation of the large amount of particulate matter that is aerosolized by the collapse of concrete and stone buildings and mixed with smoke from the generalized fires throughout a region. Depending on climatic conditions, hypothermia can also be a consideration.


The cities affected by the earthquake in Armenia were located in a mountainous, snowy region; the earthquake occurred in winter. Five hundred thousand people were homeless, and of those, many had minor to moderate orthopedic and soft tissue injuries. One of the unique acute medical problems associated with earthquakes is crush syndrome. In some ways the timing of the Armenian earthquake was quite fortuitous, considering the large incidence of crush syndrome and secondary renal failure. The American Society of Nephrology was having its annual meeting December 11, 1988. The official Soviet request for dialysis was made to the nephrologists at that meeting, and the international nephrology community responded. Hospitals in Yerevan had 10 antiquated dialysis machines. The system was overwhelmed by the almost 400 patients with acute renal failure from crush syndrome who were extricated from the rubble of the earthquake. Approximately 150 of these patients were flown to Moscow for dialysis treatment. Many others were treated by machinery sent by the international nephrology community rendering humanitarian assistance in response to the earthquake. This acute response also had positive long-term outcomes for Armenia, in that an extensive sustainable dialysis program was set up in the postearthquake days that continues to exist today. ,


Subacute injuries and medical illnesses after the impact of an earthquake often include those that patients sustain while attempting to rescue other victims trapped in the rubble. These injuries are quite common because many of the buildings in a zone devastated by an earthquake are rendered structurally unstable and are subject to further collapse if people attempt to enter them to perform hand excavation and rescue; aftershocks are common. There are also many new hazards created by the collapse of building structures and the rupture of underground utility pipes and underground or aboveground electric wires. These secondary injuries are less severe than those sustained during the earthquake; nevertheless, they require appropriate intervention if patients are to heal properly without infection and long-term disability. Illness in the subacute phase includes exacerbation of chronic medical problems no longer being treated with appropriate medications or equipment destroyed during the disaster. These illnesses may include diabetes, hypertension, coronary artery disease, and pulmonary disease. Asthma and chronic obstructive pulmonary disease often flare in response to deteriorating air quality and the rapid spread of acute respiratory illness through a population weakened by compromised nutrition, sleep deprivation, lack of clothing, housing, and food, and stress. Smoke from fires caused directly by the disaster as well as smoke from open fires used for cooking and keeping warm exacerbate these problems. Other infectious disease entities of concern include gastroenteritis from the consumption of spoiled food when refrigeration is not available and contaminated water from ruptured water mains and surface water contaminated by toxins and fecal run-off.


Chronic medical problems are seen in the weeks and months of the postimpact phase of an earthquake and include the ramifications of chronic disease entities untreated or partially treated during that time and the infectious complications of a population displaced into temporary and congested housing lacking proper food, clothing, and shelter. In addition, disruption of the social milieu may lead to psychiatric illness, including posttraumatic stress disorder (PTSD) and depression. PTSD and depression may persist for months to years after the impact. , In fact treatment for these problems both in children and adults has been ongoing for years after the Armenian earthquake. ,

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Aug 25, 2019 | Posted by in EMERGENCY MEDICINE | Comments Off on Earthquake
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