Mechanism of Microseismic Activity in Kerala - A Suggestion

The occasional incidences of microearthquakes in Kerala have been interpreted to be caused by the reactivation of ancient preexisting faults. While not negating the traditional wisdom, we propose an unconventional approach to analyze the mechanism of microseismicity in Kerala. A moot point considered here is the perceptive increase in the frequency of the microearthquakes in the state over the last decade, quite often coinciding with periods of increased rainfall. Although the occurrence of rain may not be a sufficient or necessary condition for the increase in the level of seismic activity, the correspondence between the two appears to be more than casual. On the basis of this observation. we suggest here that the tremors in Kerala may have been caused by transient increase in the hydrostatic pressure at shallow crustal depths. The mechanism of shallow earthquakes may be similar to what is proposed in the "hydroseismicity" model. Changing land use patterns, deforestation, soil erosion and increased siltation in the drainage basins are the robust parameters in this model.