User:Morgan098/Glacial earthquake

*Article Evaluation: The article is missing a lot of information. For example, where they have been found to occur, more detail about the cause of the seismic activity (what moves what), historical instances, when they were discovered, how it affects wildlife, how they affect nearby land, how they are measured, and if they can be predicted. There is also a lot of sentences and claims missing citations. However, it does provide a good overview of the topic and the content is neutral and relevant. The talk page mentions the missing citations or incorrectly used citations.

Article Draft

Lead

Glacial earthquakes refer to a type of seismic event, with a magnitude of about 5, resulting from glacial calving events. The majority of glacial earthquake activity can be seen in the late summer and are found in Antarctica, Alaska, and Greenland. About 90% of these occur in Greenland.

Article body

Discovery

Since glacial earthquakes produce large amplitude and long period waves that deviate from traditional tectonic earthquake activity, glacial earthquakes require different monitoring methods. This is a primary reason why the specific class of glacial earthquakes was not discovered until 2003. Additionally, glacial earthquakes differ from tectonic earthquakes by lasting longer; for example, a tectonic earthquake with a magnitude of 5 may last 5 seconds, while a glacial earthquake with a magnitude of 5 may last 30 seconds.

Causes of Glacial Seismic Activity

Seismic activity is seen in glacial environments due to processes such as stick-slip sliding, and the cracking and falling of ice sheets. A study conducted in 2015 connects this seismic activity to the movement of both ice sheets and the Earth in the event of calving. Calving events occurs when ice chunks break off the end of a glacier. When ice chunks break off and fall into the ocean, a large force is generated. This force can last for a couple of minutes and pushes the glacier the ice chunk originated from back and down. This is followed by a rapid rebound. This motion and movement of both ice chunks and Earth creates signals that alert to glacial seismic activity.

Seismic waves are also generated by the Whillans Ice Stream, a large, fast-moving river of ice pouring from the West Antarctic Ice Sheet into the Ross Ice Shelf. Two bursts of seismic waves are released every day, each one equivalent to a magnitude 7 earthquake, and are seemingly related to the tidal action of the Ross Sea. During each event, a 96 by 193 kilometers (60 by 120 miles) region of the glacier moves as much as .67 meters (2.2 feet) over about 25 minutes, remains still for 12 hours, then moves another half-meter. The seismic waves are recorded at seismographs around Antarctica, and even as far away as Australia, a distance of more than 6,400 kilometers. Because the movement takes place over such a long period of time—10 to 25 minutes—it cannot be felt by scientists standing on the moving glacier. It is not known if these events are related to global warming.

Global Warming

The number of glacial earthquakes in Greenland shows a peak every year in July, August, and September, and the number is increasing over time. In a study using data from January 1993 through October 2005, more events were detected every year since 2002, and twice as many events were recorded in 2005 as there were in any other year. This increase in the number of glacial earthquakes in Greenland may be a response to global warming.