Two homes collapse following a landslide, slide down a cliff in Draper, Utah

A landslide in Draper City, Utah on April 22, 2023, destroyed two homes and forced nearby residents to evacuate, with geologists pointing to the area’s volcanic ash and slope instability as potential factors.

The two destroyed houses were completed in December 2021, but the area suffered cracks in structures and the surrounding ground in early 2022. Despite stabilization attempts, the owners had to evacuate in October 2022.

Dr. Dave Petley of The Landslide Blog commented on the possible causes of the landslide. He suggested that the underlying cause might be related to the slope itself, with two possible explanations: the failure could have developed in the fill slope or the materials upon which the fill was placed, likely of volcanic origin, might have failed. A proper investigation is necessary to verify the cause.

Ben Erickson, a geologist with Utah’s Division of Wildlife Resources, surveyed the destruction from a helicopter and noted that the area is prone to landslides. He identified more nearby landslides, but none as large as the one that hit residents on April 22. The ground in the area consists of volcanic ash deposited approximately 35 million years ago, making it highly conducive to landslides.

Erickson explained that slopes can complicate engineering efforts to achieve a safety factor in home builds. The geotechnical data should have been used to establish stability requirements for the homes, but unfortunately, the plans did not work out. Visible cracks at the base of the slope indicated stresses that needed to be relieved at the surface due to the weight pulling the ground apart.

The geologist urged caution around the impacted area and other landslide-prone areas with unstable ground. He advised respecting safety parameters put in place to protect anyone near or curious about the site.

References:

1 Utah geologist gives exclusive insight into Draper collapses – KSLTV – April 24, 2023

² The 22 April 2023 landslide in Draper in Utah – The Landslide Blog – April 25, 2023

Featured image credit: The City of Draper