Not all landslide dams are formed by earthquakes, but any landslide dam can be used to find out more about how long they stay in the landscape and what hazards they may pose. The landslide itself can impact people and property, but when the debris blocks streams and rivers, the dam and impounded reservoir can cause flooding upstream and downstream when the dam fails and discharges the impounded reservoir and debris.
In 2019, as a result of a rainfall event, the Kaiwhata landslide located in the Wairarapa, created a dam and reservoir. Soon after its formation the dam breached and the reservoir emptied, which sent a flood wave downstream inundating the area with water and debris.
In November 2020, the landslide reactivated following a heavy rain event, and formed a new landslide dam and impounded reservoir, which is still present (as at December 2020).
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