After a certain magnitude, earthquakes are devastating anywhere they occur. Destruction is caused by them and at a large scale. Many cities and towns get buried under debris because of the shaking and aftershocks. There are some many things associated with earthquakes that can’t be explained
The Great African rift valley is a living example of constant earthquakes occurring in the region.
But, evidently, earthquakes can be beneficial to plants as the shaking and the tectonic movement causes ground water level displacement that serves as a recharge and promotes growth of trees.
A team of researchers, led by first author hydrologist Christian Mohr from the University of Potsdam in Germany, explains the thought behind the study as – “Large earthquakes can increase the amount of water feeding the stream flows, raise groundwater levels, and thus grant plant roots more access to water in water-limited environments. If tree growth is limited mainly by water, trees should in theory record hydrological responses to earthquakes by changing their growth rates.”
In 2010, the Maule Region in Chile was adversely affected by an earthquake of a powerful 8.8 magnitude. The researchers, to test their hypothesis, studied Pinus Radiata (species of pine native to the Central Coast of California and Mexico) in Chile.
The hypothesis – Earthquake alterations to groundwater supply would promote tree growth when trees are close to valley streams, but hinder their growth if they are higher up on hillsides.
In 2014, tree cores in the valley as well as on the hill slope ridges were extracted and analyzed, showing that on one hand, some trees in the valley did experience temporary increased growth after a quake, on the basis of both tree ring evidence (increased lumen area), and in the ratio of carbon isotopes in the tree’s cells, giving a cellular-level perspective on aspects regarding plant health, growth and water availability. On the other hand, some trees on the slopes didn’t fare so well in the same period, offering some support to the researcher’s hypothesis, although the team acknowledges the overall effects of the earthquake were slight, and only seemed to last for a period of weeks.
The researchers write – “The post seismic changes in lumen area and carbon isotope ratios can be used to study tree growth and photosynthetic responses to earthquakes. As a case study demonstrating how these techniques can be used in the field. We might have a new tool to study earthquakes of the past. Details in wood anatomy and isotopes might offer a tree-based approach for paleo-seismology beyond simply considering width.”
