A soil mound of over 50m high, that exceeded the permitted size regulations, triggered the landslide due to the excessive rain.

[3] There were indications highlighting the possibility of a landslide occurring in the preceding months due to the rainfall patterns and early warning systems.

Atami is a pacific coastal city, located 68 miles south east of Tokyo, Japan, in the eastern most tip of the Shizuoka Prefecture and northeast of the Izu Peninsula.

[7]Atami is originally known for its hot springs and now attracts tourists with the addition of museums exhibiting Japanese culture and vast variety of ocean water sports.

[3] Heavy rainfall combined with the geographic characteristics may have affected slope stability and played an important role in triggering the landslide.

[3] The soil along the Atami debris flow path is composed predominantly of lava and pyroclastic fall deposits from the Hakone Volcano, which may have theoretically made this region susceptible to landslides.

[11] However, there was also a landfill formed at the head of the Aizomegawa River using illegal and inappropriate construction methods, resulting in inadequate drainage and large amount of sediments, decreasing slope stability.

[6][14] The extent of damage caused by the Atami landslide was also contributed due to the high slope of almost 400m from starting point to the sea.

[17] A lack of family support were prevalent due to hundreds of people displaced after the landslide, which also has an effect on mental health.

[18] - The risk for vector borne diseases are increased due to long term environmental changes caused primarily by the alterations in river flow and deforestation.

The landslide resulted in significant damage of local plant life/ flora which ultimately formed part of the debris flow.

[18] In the immediate aftermath of the disaster, Japan's emergency services went into action, with firefighters, police, and the Self-Defense Forces conducting search and rescue operations.

[21] After the 2021 Atami landslide, investigations revealed that illegal dumping of dirt and poor construction methods were responsible for the disaster.

In addition, the Government took legal action against those responsible, emphasizing the policy implications and committing itself to stricter enforcement of construction and land-use regulations.

Reconstruction efforts have focused on restoring basic infrastructure, such as roads and utilities, and providing financial support to affected residents.

[22] At the same time, authorities have implemented stricter land-use regulations and conducted extensive reviews of similar development projects across the country to prevent future disasters.

Monitoring systems and early warning technologies are being improved, and the Government has prioritised sustainable development to reduce the vulnerability of high-risk areas to landslides.

The Atami landslide, caused by heavy rainfall and compounded by human activity, provides several critical lessons for disaster risk reduction, urban planning, and climate adaptation.

The key insights are as follows: The disaster investigation revealed that excessive and unregulated accumulation of soil and debris in a designated residential development area significantly exacerbated the landslide.

This underscores the necessity of stricter enforcement of land-use regulations and regular inspections, especially in areas with steep terrain and high rainfall.

This emphasizes the need to incorporate climate resilience into urban planning and infrastructure design, especially in regions prone to hydrological and geological hazards.

Enhanced community-based disaster preparedness programs, clear evacuation protocols, and robust early warning systems are crucial to reducing casualties in similar future events.

[23] These tools provided a clearer understanding of the causes and effects of the landslide, showing the value of integrating cutting-edge science into disaster risk management.

Making geo-spatial, hydrological, and urban planning data accessible can help communities and governments co-develop risk reduction strategies.