Final answer:
The hazard most likely to occur with little or no warning is a tsunami, due to their sudden triggering by underwater seismic events. Landslides are also sudden and can be triggered by various factors without warning.
Step-by-step explanation:
The hazard most likely to occur with little or no warning is a tsunami. Tsunamis can be triggered by underwater earthquakes and other seismic events, often giving communities very little time to react before they strike. Unlike hurricanes, which can be tracked and predicted days in advance, or volcanic eruptions, which often show signs of increased activity beforehand, tsunamis and landslides can happen abruptly, leaving little time for emergency response. In particular, tsunamis caused by offshore events can arrive at coastlines within minutes. However, landslides are also sudden hazards that can be triggered by several factors like heavy rainfall, earthquakes, volcanic eruptions, or human activities and often occur without warning, resulting in significant damage and fatalities.