Lahars have also headed down the Whakapapanui Valley and through Whakapapa Skifield. In the winter months 7000 people may be found on Whakapapa Skifield. The shape of the mountain protects other areas from lahars. Signals from these earthquakes are sent to a computer at the DOC visitor Centre at Whakapapa. The computer determines whether the earthquake is local or far away.
Local earthquakes are a possible sign of increased volcanic activity.
If the earthquake is local and above a certain size the alarm bells will ring on Whakapapa Skifield and within Whakapapa village. If the lahar moves down the Whakapapanui stream extra alarm bells will ring in Whakapapa village. If you hear a prerecorded message warning of a lahar, quickly move to the nearest ridge. A trip wire is also located in Skippers Canyon. Just in case the Crater Lake wall collapses sending a lahar down the slope.