At sunset, the Crater Lake volcano in the Cascade Range of Oregon is shrouded in the smoke of a wildfire ignited by a lightning strike.
The devastating eruption of the stratovolcano Mount Mazama 6,900 years ago emptied the interior of the volcano. Under its own weight, the volcano collapsed into a ring structure eight kilometers (5 miles) wide and ten kilometers (6 miles) long. Later, this 1,200 m (4,000 ft) deep caldera filled with rainwater to about half its depth, forming the deep-blue Crater Lake. The color of the water indicates its purity.
Mount Mazama was about 4,000 m (13,100 ft) tall and probably looked similar to today’s Mount Rainier. After the collapse, the present-day rim of Crater Lake is at an altitude of 2,200 m (7,200 ft). It is beyond human experience to imagine a cataclysmic volcanic eruption destroying such a high volcano and leaving behind a 1,200 m (4,000 ft) deep hole.
Wizard Island is a volcanic island that rises from Crater Lake and represents the third generation of the volcano after Mount Mazama and Crater Lake. If this growing lava dome does not explode again prematurely, it will one day completely fill the caldera and continue to grow into the next large stratovolcano.
The steep crater walls reveal that Mount Mazama was heavily glaciated before its blast into oblivion. Several deep notches are vertical cross-sections of former U-shaped valleys in which the glaciers were located. These glaciers melted abruptly during the catastrophic eruption and intensified the explosion when ice and water came into contact with the lava.
