(KHNL) - Heavy rains are in the forecast and a University of Hawaii Geologist says they could affect already unstable hillsides on all islands.
You can't drive far on the Big Island without coming across a rockslide caused by the earthquakes.
University of Hawaii Geologist Steve Martel explains, "The shaking can cause cracks to open for example if there is a cliff starting to topple over the shaking can cause cracks to open and that can cause toppling to happen."
Martel explains those heavy rains in the forecast could compound the problem.
"Right now, in the wake of the earthquake, slopes that might have been relatively stable under conditions may have been destabilized a little bit and if more rain comes in now, the effect of water pressure and slope going up that is another straw that can be added," says Martel.
In the past rockslides and flooding have occurred in this neighborhood above Aina Haina Elementary.
Ominous boulders dot the hillside.
After Sunday's earthquake, some homeowners worried.
Joann Fuentes says, "At the time I thought about it but I was busy looking around but my husband called and asked if the two big rocks hanging on the cliff in the backyard were still there. Yes they were."
Joann Fuentes says heavy rain sends rocks sliding down the hillside but her home is protected. And the problem is rockslides are hard to predict.
It is very difficult to specify which places are prone to failure because of a lot of variables exist in the ground.
Geologists with the State Department of Land and Natural Resources are on the Big Island.