This research project examined both experimentally in California, from April 2016 to September 2018, and in the field in Nepal after their 2015 earthquake in 2016 and 2017, the impacts of earthquakes on shoot growth, root damage, reproduction and growth period of trees. The experimental research used a shake table to simulate an earthquake of 7 (on the Richter scale) on 24 Aesculus californica trees in 20 gallon containers. Another 24 A. californica trees, of the same age served as controls. All were in sun 10 hours per day and had identical conditions for soil, water and nutrients. All trees were allowed to grow for three seasons. Eight individuals of four species of trees (Dryobalanops aromatica, Brugmansia suaveolens, Quercus aquifolioides , Juglans regis) between 5 and 25 years of age were examined in both the areas of Nepal where shaking was severe (zones VII and VIII on USGS intensity map ) and where it was almost negligible, (zone II weak intensity).
Results/Conclusions
Both the experimental and field study revealed shoot growth of trees was significantly decreased in shaken trees. For some species (Quercus aquifolioides) shoot growth was almost negligible for two years. Reproduction was significantly lower for two years on experimental A. californica trees and two species recovering from severe shaking in Nepal (Quercus aquifolioides , Juglans regis). Root damage was greater on four year old (37%) than two year trees (22%) of A. californica . The experimental A. californica trees had bud break 10 to 14 days later than controls but retained leaves 10 -12 days longer at the end of the season.