Let Peak

Let Peak
Lassen Peak and Devastated Area from Cinder Cone from
height	3189  m
location	California , USA
Mountains	Cascade chain
Coordinates	40 ° 29 ′ 17 ″  N , 121 ° 30 ′ 18 ″  W Coordinates: 40 ° 29 ′ 17 ″  N , 121 ° 30 ′ 18 ″  W
Topo map	USGS Lassen Peak
Type	Lava dome
Age of the rock	<27,000 years
Last eruption	1917
Normal way	Hiking trails

The Lassen Peak in the State of California is the largest lava dome - Volcano (also known as plug dome ) of the earth and the southernmost volcano in the Cascade Range . It is also known as Mount Lassen . It was formed on the destroyed northeast flank of Mount Tehama , a stratovolcano that was at least 300 meters higher than the Lassen. Lassen is located in northern Shasta County in central California in the Shasta Cascade Region and is the center of Lassen Volcanic National Park .

It is the only volcano in the Cascade Range other than Mount St. Helens , which was active during the 20th century . This phase of eruptive activity lasted from 1914 to 1917.

In contrast to most volcanoes of the lava dome type , Lassen is crowned by craters. There are a number of craters near the summit, but two of them are covered in massive lava.

geology

Years ago, about 27,000 one was dacite - lava dome pushed through the northeast face of the Tehama upwards. In this way, the rock layers above were broken up and deposited as a talus around the emerging volcano. Lassen Peak reached its current height in a relatively short time, probably in just a few years. It was partially eroded by glaciers during the Ice Age.

history

Before the arrival of the white settlers, the area around Lassen Peak, especially in the east and south, was the tribal area of ​​the northeastern Maidu .

Lassen Peak was named after the Danish blacksmith Peter Lassen , who brought settlers from the east to the Sacramento Valley around 1830 . His route was not used for long because it was considered unsafe. The Nobles Emigrant Trail , named after William Nobles , who connected the Applegate Trail in Nevada with the northern Sacramento Valley , replaced it.

In 1864, Helen Tanner Brodt became the first woman to climb Lassen Peak. The name of a cirque lake reminds of them .

From 1914 to 1921 it big active with steam explosions, dacite -Lavaflüssen and lahars . There were between 200 and 400 eruptions during this time, but none of them were dead or seriously injured.

On May 5, 1915, Dazite lava flowed 300 meters down the western slope before solidifying. Observers 30 kilometers away described this process as a "boiling mountain". The heat of the lava melted the snow cover and destroyed the deep crater lake at the summit. The resulting lahar flooded Lost Creek and Hat Creek.

Explosion and ash cloud on May 22, 1915

On May 22nd at 4:30 p.m. local time, a huge explosion followed, which caused a mushroom-shaped ash cloud. A pyroclastic current destroyed and burned trees on the northwest slope and triggered another lahar. These events formed the so-called Devastated Area , which is still almost tree-free, as the soil is poor in nutrients and very porous.

Another series of steam and ash explosions occurred in April, May, and June 1917, creating a fourth summit crater (in the northwest).

Since then, the USGS has been monitoring the Lassen and its surroundings in cooperation with the United States Park Service .

The Loomis Hot Rock is the most famous of the many rocky blocks that reduce plunged in Lahar from May 22, 1915

Web links

Commons : Lassen Peak  - collection of images, videos and audio files

• The Official Lassen Volcanic National Park Web Site
• USGS: Eruptions of Lassen Peak, California, 1914 to 1917

swell

• Geology of National Parks: Fifth Edition , Ann G. Harris, Esther Tuttle, Sherwood D., Tuttle (Iowa, Kendall / Hunt Publishing; 1997) ISBN 0-7872-5353-7