1999 A bad year for earthquakes

At least 20,000 people died in six serious earthquakes in 1999, and many more were left injured and homeless. The worst of these earthquakes was in northwest Turkey in August, when more than 16,000 people died in the densely-populated area around Izmit. In October California was ‘lucky’ because a major earthquake occurred in the Mojave Desert rather than near Los Angles, 160 km away.

All this does not mean that earthquakes are becoming more frequent or more powerful than in the past. The difference is that more people are at risk as the world population grows. Rich countries have been able to cut the death toll from earthquakes by developing anti-quake technology and building ‘flexible’ buildings that sway during tremors. This has not happened in poorer countries, where poor-quality buildings and rapidly-growing populations have increased the danger.

The devastation caused by the Turkish earthquake was much worse than it need have been. Scientists had warned that the country’s industrial region, as well as thousands of homes, had been built in the area of highest seismic risk.

The number of potential earthquake victims has also been increased by the migration of people from rural areas to towns, where they tend to be much more crowded together. This is a particular problem in high-risk areas like the Pacific rim.

Limestone in Europe

Limestone landscapes are distinctive and widespread. The rock occurs in a number of different forms and, depending on the historical and present-day climate, it will give rise to a variety of landforms. Across Europe the various types of limestone produce spectacular scenery. The term karst, which comes from a region in Slovenia, is often used to describe such landscapes. They are found through Slovenia, Croatia, Bosnia-Herzogovina, Montenegro and Albania.

Mountain limestones occur throughout the Alps, extending westward to France. Beyond the Alps limestone is found in the Grands-Causses region of the Massif Central, where the Tarn and Lot rivers have cut steep gorges.

Limestone also forms the underlying geology of many Mediterranean islands. Throughout southern Europe these rocks owe their origin to deposition in the ancient Tethys Sea, of which the Mediterranean is a small remnant. They have been lifted by tectonic forces and eroded by water and ice to produce the steep slopes,, gorges and caves associated with the rock.

Limestone also occurs in northern Europe, where it is the product of deposition in much more ancient seas. In the English Pennines limestone was formed some 350 million years ago in the Carboniferous period. Around Ingleton and Malham in Yorkshire we can see, on a micro scale, the karst features typical of those in eastern Europe.

Vulcanism

A volcano is an opening in the earth’s crust through which molten rock, usually called magma while underground and lava aboveground, pours forth. Because the emerging material accumulates near the orifice, most volcanoes in the course of time build up mountains with a characteristic conical shape that steepens toward the top, with a small depression or crater at the summit. Lava escapes almost continuously from a few volcanoes, but the majority are active only at intervals.