Nevada Earthquake Swarm, Precursor?
Hundreds upon hundreds of earthquakes have suddenly rumbled beneath an area 6 miles to the southwest of Hawthorne, Nevada, just during the past few days. Seismologists are expressing concern of this sudden activity partially because it is occurring on a previously unknown fault – similar to what happened not long ago in New Zealand, Chile, Haiti, Baha, and Japan.
There is further concern due to the fairly large magnitude of many quakes, lots being in the 4 range while the largest has been a 4.6 so far in this swarm event. Nevada Seismologists apparently have no way of knowing if this will lead to a big quake.
Given the volcanic activity in the region during the past 10,000 years, seismologists are looking for tell-tale signs (tremor). A new volcano on the border of Nevada / California would be an interesting situation indeed. They say though that this activity may be tectonic, but they are checking all scenarios.
Having a look at the entire list of earthquakes at the Nevada Seismological Laboratory, most of the depths are approximately in the 3 – 10km range, more or less. The USGS list indicates depths closer to 15km while the USGS list itself has recorded only a fraction of the total number of earthquakes reported at the University of Nevada site.
The location is curiously close to a dormant Super Volcano, Long Valley – California, just 45 miles away. In fact there is a string of volcanoes there, Mono Lake volcanic field – Mono Craters, Long Valley, Inyo Craters, and Mammoth Mountain. The region has a rich history of volcanic activity including planet wide consequences such as when Long Valley covered most of the western United States in thick ash.
In either case, be it volcanic or tectonic activity in western Nevada, people need to be prepared and aware of what is happening around them. Even the local seismologists are saying to have a supply of food and water at the ready, as earthquakes can happen just about anywhere.
We have witnessed a tremendous number of powerful and very deadly earthquakes during just the past few years. The last one near Japan was of such great magnitude and significance that it reminds us of the fact that we’re living on top of a thin crust that can snap at any moment – and where just a few miles down much of it is molten. Unimaginable stresses are built up all over the various tectonic plates which are essentially floating and jostling around above a semi fluid sea of hot thick molten rock.
Update, 19-Apr-2011, 1530 UTC
The swarm continues – 67 earthquakes during the past 24 hours as of this moment.
Map of Nevada Earthquake Swarm
Update, 20-Apr-2011, 1830 UTC
36 more earthquakes during the past 24 hours, most of them at a depth of approximately 5 km (some of them shallower) with magnitudes ranging in the 1’s and 2’s.
The earthquake swarm is reminiscent of a recent swarm near the Icelandic volcano, Krisuvik during the end of February. The swarm was quite alarming – some thought an eruption was imminent (including me), although the swarm ceased and has been quiet since.
A ‘contact’ in the business of seismology and volcanology says that volcanic magmatic scenarios are not implausible, as there are old fault lines that are dormant – and magmatic movement could find an easy path along fault lines. BUT magma can sit in a caldera and do nothing for
thousands of years.
Update, 21-Apr-2011, 1630 UTC
The sequence has subsided, with just 7 earthquakes in the immediate vicinity during the past 24 hours of this update. The area remains under close scrutiny.
Update, 22-Apr-2011, 1630 UTC
The swarm sequence has picked up a bit, now with 11 quakes during the past 24 hours. The pattern appears to be moving to the north, about 2 miles from where they began.
There appears to be an additional new ‘mini swarm’ developing 100 miles to the southeast of the Hawthorne Nevada earthquake swarm. There have been about two dozen quakes, approximately 7 during the last 24 hours.
Update, 23-Apr-2011, 1800 UTC
After a short period of subsiding, the frequency of occurrence continues to increase a bit, with 14 earthquakes registered during the last 24 hours at the Hawthorne swarm location.
The mini-swarm that developed 100 miles to the southeast has only popped on quake during the past 24 hours.
Of keen interest though, is a new location of about a dozen earthquakes located on the northeastern edge of Mono Lake (Mono Lake volcanic field), just 20 miles to the southwest of the Hawthorne swarm.
This is getting interesting.
Update, 24-Apr-2011, 1700 UTC
11 more earthquakes during the past 24 hours at the Hawthorne location. The quakes of the past few days remain concentrated on the north side of the area of major activity.
Only 2 more quakes at the Mono Lake vicinity referred to yesterday.
Update, 25-Apr-2011, 1600 UTC
Last 24 hours: 20 more earthquakes at the Hawthorne, Nevada swarm vicinity.
Update, 28-Apr-2011, 1600 UTC
The Hawthorne swarm has not stopped. Number or quakes range from several to nearly 20 per day. Yesterday, a strong magnitude 4.3 struck the area – only 2.5 km depth.
Update, 2-May-2011, 1600 UTC
The earthquake swarm persists. 16 quakes during the past 24 hours.
A Reader who happens to be in the geological industry emailed and said that the crust in this region is very thin, comparatively speaking, the region is spreading apart and may one day look like the Rift Valley in Ethiopia (not any time soon). However it is plausible that a cinder cone eruption could occur here, and teams are investigating.
Earthquakes continue at the location near Hawthorne, Nevada. While the frequency of occurrence is less than the onset of the swarm, there were 9 quakes during the past 24 hour period for example. Most of them have been within the magnitude 1 and 2 range. One however surely provided a good jolt measured at magnitude 3.9.
Most quake depths have been located at about 5 km.
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