Geological hazards commonly occur in an area with high tectonic activity in the Pacific Ocean known as the ‘Ring of Fire’, which runs for 40,000 km. 75% of the Earth’s volcanoes are located along the Ring of Fire, and 90% of earthquakes occur here.

Landslides are more widespread than any other geological event, and can occur anywhere in the world. They occur when large masses of soil, rocks or debris move down a slope due to a natural phenomenon or human activity, and can accompany heavy rains or follow droughts, earthquakes or volcanic eruptions. Mudslides or debris flows are also a common type of fast-moving landslide.^{9 9} WHO: LandslidesX

Earthquakes
Health impacts of earthquakes vary according to the magnitude of the earthquake, the nature of the built environment (such as poor housing or urban slums), and the secondary effects of the earthquake, like tsunamis or landslides. Earthquakes can have immediate and long-term impacts on health.

Immediate health impacts include:

• trauma-related deaths and injuries from building collapse;
• trauma-related deaths and injuries from the secondary effects of the earthquake, like drowning from tsunamis or burns from fires.

Medium-term health impacts include:

• secondary infection of untreated wounds;
• increased morbidity and risk of complications related to pregnancy and childbirth due to interrupted obstetric and neonatal services;
• potential risk of communicable diseases, particularly in areas affected by overcrowding;
• increased morbidity and risk of complications of chronic diseases due to interruption of treatment;
• increased psychosocial needs;
• potential environmental contamination by chemical/radiological agents following destruction of industrial infrastructure.

Earthquakes can also damage health facilities and transportation, which can disrupt service delivery and access to care. Health workers may not be able to reach health facilities that are still functional and medical supplies may be lost.^{10 10}WHO: EarthquakesX

Landslides
Landslides can cause high mortality and injuries from rapidly flowing water and debris. The most common cause of death in a landslide is trauma or suffocation by entrapment.

Broken power, water, gas or sewage pipes can also result in injury or illness in the population affected, such as water-borne diseases, electrocution or lacerations from falling debris. People affected by landslides can also have short- and long-term mental health effects due to loss of family, property, livestock or crops.

Landslides can also greatly impact the health system and essential services, such as water, electricity or communication lines.^{11 11} WHO: LandslidesX

Earthquakes can strike suddenly and without warning, and can result in the ground shaking, soil liquefaction, landslides, fissures, avalanches, fires and tsunamis. The extent of destruction and harm caused by an earthquake depends on:

• Magnitude
• Intensity and duration
• Local geology
• The time of day that it occurs
• Building and industrial plant design and materials
• The risk-management measures put in place.

Impacts occur through multiple avenues:

• Disruption of livelihoods, population displacement can have impacts on mental health
• Long-term healthcare services can be compromised due to impacts on infrastructure
• Increased disease risk as a result of contaminated water supplies, compromised water sanitation and hygiene and the effects of malnutrition from lack of adequate food supplies

• Those living in tectonically active zones
• Those living near a volcano
• Those living in areas most vulnerable to landslides, including:
  • steep terrain, including areas at the bottom of canyons;
  • land previously burned by wildfires;
  • land that has been modified due to human activity, such as deforestation or construction;
  • channels along a stream or river;
  • any area where surface runoff is directed or land is heavily saturated.

Climate change and rising temperatures are expected to trigger more landslides, especially in mountainous areas with snow and ice. As permafrost melts, rocky slopes can become more unstable resulting in a landslide.^{12 12} WHO: LandslidesX

It is crucial that countries work to mitigate, prepare and respond to earthquakes, landslides and other geological hazards. This includes:^{13 13}WHO: EarthquakesX

• strengthening health emergency risk management systems;
• limiting the risk of exposure to earthquakes by improving the quality of the built environment, with better land-use control, including regulating building;
• ensuring that health facilities are resilient to hazards, and that they are able to remain functional and able to respond to increased and changed health needs after earthquakes, with staff trained appropriately;
• mobilizing medical response teams, including establishing temporary health structures and field hospitals, as well as emergency medical kits;
• investing in community preparedness, as local residents are often the first responders.