ALT Anthropogenic influences on tsunami hazard. a, Illustration of the potential benefits of natural coastal habitats consisting of healthy coral reefs and marine life, coastal forests and sand dunes in mitigating tsunami hazards. These natural ecosystems can act as a buffer zone by decreasing the maximum wave height and inland reach of a tsunami. However, the effectiveness of these defences depends on tsunami size. b, Anthropogenically modified coasts can have one or more of the following: relative sea-level rise from subsidence related to excessive groundwater withdrawal, degraded or destroyed natural ecosystems, such as coral reefs, mangroves and seagrass meadows, and removed sand dunes. These anthropogenic modifications can lead to local amplification of tsunami hazards, such as increased inland reach.