By Paulette Cully
In an upcoming article in the Geographical Journal Chester and Chester examine the ‘Impact of eighteenth century earthquakes on the Algarve region, southern Portugal’. Using data collected in the field and archival information the authors discuss the economic and social impacts on the Algarve of the two earthquakes and their related tsunamis which took place in 1722 and 1755. Using the information gathered, the study also focuses on the lessons which have been learnt for future hazard planning in the region.
Similarly, a recent news article marking the fiftieth anniversary this month of the largest earthquake ever recorded (magnitude 9.5), which took place in southern Chile in 1960, charts the life saving legacy that the quake left in its wake. Not only was the quake the largest ever recorded but it approached the upper limit that the planet is capable of producing in a single event. With an equivalent energy of 20,000 times the Hiroshima bomb, the quake caused the earth to wobble and sent it ringing for many days. The Chilean quake would become part of a convincing argument in support of the far-reaching plate tectonics theory and provide a textbook illustration of a subduction zone earthquake. The earthquake produced a tsunami 25 metres high which travelled across the Pacific reaching Japan 17,000 kilometres away where it killed 140 people. This spurred nations bordering the Pacific to set up an international tsunami warning system. In addition, deposits left by the tsunami have allowed geologists to develop a model which helps them identify other areas which may be prone to giant subduction zone earthquakes.