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Introducing The Salton Sea Buttes Volcanoes

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  • Location: Coventry,Warwickshire
  • Location: Coventry,Warwickshire

My intention is to produce a series of articles (depending on interest) which introduces ideas about volcanic and earthquake activity. I want to go slightly off the beaten track to explore oddities, volcano hazards, analysis methods, Wonders and Mankind’s impacts. Keep in mind I am not expert (corrections gratefully received), but hopefully these will at least give a flavour of some different places in the world and provide a few minutes escape from people’s troubles.

Introducing The Salton Sea Buttes Volcanoes



Reason for Interest
Volcano activity in Southern California tends to escape attention due to the priority concerns with earthquakes. With volcanic activity in the Salton Sea area being younger than originally thought and crustal extension (rifting) being held back by the locked San Andreas Fault the area needs monitoring. The volume of melt material below the area is thought to be very large so we should not assume that future volcanic activity in the area would be quite as benign as it has been till now. This is probably why the USGS now consider this area to be of particular concern. Maybe what really piques my interest is seeing a side to California you don't normally see.

The Setting
One of the world's largest inland seas and lowest spots on earth at -227 below sea level, Salton Sea was re-created in 1905 when high spring flooding on the Colorado River crashed the canal gates leading into the developing Imperial Valley.  For the next 18 months the entire volume of the Colorado River rushed downward into the Salton Trough.  By the time engineers were finally able to stop the breaching water in 1907, the Salton Sea had been born at 45 miles long and 20 miles wide and 51 feet deep. 




In the 1950’s the Salton Sea was the place to vacation for Hollywood stars. The Hollywood influx quickly turned this small vacation getaway into an attraction drawing in 500,000 people a year.  Star-filled clubs such as Ace & Spades and the 500 Club sprouted up and recreational boating took off.  Many celebrities would come from Los Angeles and down from Palm Springs to take part in the beach life and great water sports offered at Salton Sea. Increasing salinity in the Salton Sea basin has limited the number of types of fish that can be found there, and most fish currently caught are Tilapia. The once-bustling hotels are derelict, broken wooden frames of buildings stand in some spots as other structures are badly decaying with graffiti spray painted over the boarded-up windows and doors. On hot summer days when the temperature can reach up to 120F (48.8C), a pungent Sulphur odor hangs in the air that can be smelled 150 miles away in Los Angeles. 



Near the Salton Sea can be found Salvation Mountain which Leonard Knight used 30 years of his life and gave up everything to build this colorful masterpiece.  In 1984, Leonard was set out to spread the word of the bible and when his truck broke down he starting building Salvation Mountain on the very spot and lived onsite until 2012 when he was moved to a nursing home.


Nearby can be found East Jesus a community of artists that live together, create art and party in the desert.



The imperial sand dunes to the south of the sea are a 15 mile long and 3 mile wide stretch of 400 foot tall sand dunes.  The Dunes have been the home to the tapping of many movies including Stars Wars and is a huge haven for dune buggy enthusiasts. 

The Date Farms are the most important part of the Salton Sea area’s economy today.  Ever since the celebrities and tourists stopped coming in the 1960’s most of the area has become a rundown, dingy area, but the Date Farms have stayed strong.

To the North of the Sea is Palm Springs which is like a mini desert Hollywood.  Well it’s not quite filled with the high level of stars it was in the 50’s when the Salton Sea was booming but it is still a beautiful place to visit.  

 If you’ve ever wondered what Jurassic-sized palm trees may have looked like then the Anza-Borrego State Park and Palm Canyon is your chance to see.  This grove of 100 foot tall bushy palms is crazy.  The park is located to the west of the Salton Sea. Joshua Tree National Park is in southeastern California, east of Los Angeles and near Palm Springs and north of the Salton sea it is named after the Joshua trees native to the Mojave Desert. Between San Diego and the Salton sea is the Anza-Borrego Desert State Park.

The Tectonic environment
The Salton Sea is a large shallow lake located in the central Salton Trough of Southern California. The lake covers the southernmost extension of the San Andreas Fault (SSAF), where the fault takes a southwestward step to the Imperial Fault (IF). The region around the SSAF is actively being stretched due to extensional deformation. Numerous faults, high levels of seismicity and a series of young volcanic buttes suggest this region may be a source for future geohazards.

The Salton Trough is an on shore analog to those rift systems in the Gulf of California. It includes the Coachella Valley, Salton Sea, Imperial Valley, and Mexicali Valley from northwest to southeast. The northern Imperial Valley and southern Salton Sea are seismically highly active. Seismicity occurs at 3–8 km depth in the Salton Sea geothermal field at the southeastern shore of the Salton Sea, 3–11 km depth in most of the Brawley Seismic Zone. The entire valley is also characterized by very high heat flow.



Brawley Seismic Zone
The Brawley Seismic Zone is a north-striking zone of northwest and northeast-striking faults that extends from the southern end of the San Andreas fault to the northern end of the Imperial fault. Across this zone crustal spreading occurs within the transition from the Gulf of California mid-ocean ridge to the San Andreas transform fault. The largest earthquakes to have occurred on the cross-faults were the magnitude 6.2 Elmore Ranch event in 1987. Although the Brawley Seismic Zone activity is clearly proximal to the southern San Andreas fault, the San Jacinto fault zone, and the Imperial fault, the current activity is remaining more than 10 km distant from any of these major faults. Repeated swarms occur in the Seismic zone as rifting occurs but there is no suggestion that these swarms are volcanic in nature. Three times in the last 15 years in 2001, 2009, and 2016, clusters of small earthquakes occurred within a few kilometers distance of the southern terminus of the SAF, within the northern Brawley Seismic Zone at a depth of 3 - 10km.

There has been some concern that stress releases in the Brawley Seismic zone could trigger larger earthquakes on the San Andreas fault. The relative likelihood of such an occurrence was considered to be high because the southern SAF ruptured last in a major earthquake more than 320 years ago and the average recurrence rate of large earth-quakes on the southern San Andreas fault is  about 180 years. Recent research however suggests that there is likely very little transfer of stress from the Brawley Seismic Zone and to the San Andreas fault. There is however very little research on the impacts to the Brawley Seismic Zone as a result of a significant San Andreas fault earthquake and we are left to guess whether this would lead to enough extension for volcanic activity to initiate again.



The Volcano
The Salton Buttes are a group of volcanoes in California in the south eastern part of the Salton Sea. They consist of a 7 kilometer long row of five lava domes each no more than 1 kilometer wide. From North to south they are Mullet Island, North Red Hill, South Red Hill, Rock Hill and  Obsidian Butte. Obsidian Butte is surrounded by a lava flow, and Mullet Island has a characteristic "onion-skin" foliation with hot springs. 

The domes were formed by effusive eruptions, but at least Obsidian Butte and South Red Hill also experienced explosive eruptions, which at Obsidian Butte preceded the effusive eruption stage. The lava source for the volcanoes is a magma chamber beneath the Salton Sea, which also heats water for a nearby geothermal plant. 

These volcanic domes are associated with a local northeast-striking magnetic high that is interpreted  to be caused by a magnetic mass, 30 km long, 3 to 12 km wide, and about 4 km thick, with its top buried more than 2 km below the surface. The intrusion under the Salton Sea is thought to be a pluton, an arm or protrusion from a deeply buried molten magma. This intrusion is parallel to the axis of the Salton Trough. 

Geophysical evidence shows that liquid magma is still present underneath the Salton Buttes. The buttes last erupted between 940 and not 30,000 years ago as previously thought with the U.S. Geological Survey  listing the area as a high threat for future blasts.

Hot Springs
The Hot springs within Salton sea area were known and used by Indians for centuries. The first commercial development in the area dates from the turn of the century, when a therapeutic spa was opened in the foothills of the Chocolate Mountains near Bombay Beach on the east shore of the Salton Sea. This spring is still in use, and is unusual for its high water temperature, ranging from 135 to 180 degrees Fahrenheit. The hot springs are concentrated in a linear pattern along the eastern side of the valley. The line of springs extends from Desert Hot Springs into Mexico, and the arrangement strongly suggests that the warm waters are reaching the surface using fractures of the San Andreas fault system as conduits.


There are several experimental geothermal developments in the Imperial Valley, extending from the south shore of the Salton Sea into Mexico. The Salton Sea geothermal field is the largest and the hottest of the several fields in the Salton Valley, and has the longest history of development.


The mysterious mud spring
Refusing to stay in place, a roiling mass of carbon dioxide and slurry-like soil is migrating across the state at a pace of 20 feet a year.  Scientists currently have no real idea why it’s moving or if it can be stopped. Currently located just north of Niland, the mud spring is moving toward Union Pacific Railroad tracks and giving engineers there a headache. A well dug to depressurize the source of the gas had no effect. Steel walls driven 80 feet into the ground were also nonchalantly circumvented; the mud pot simply ducked under them and continued its freakishly linear path of destruction. Mud pots and mud volcanoes  generally don’t emit much water, but this one is extremely vigorous, producing somewhere around 40,000 gallons of water a day. This mud spring is close to—but not on—the Wister Fault, a southeastern extension of the San Andreas. However, it appears to be tracing a path that’s at right angles to the region’s major faults.


Recent Activity
In late August 2005, a swarm of more than a thousand earthquakes between magnitudes 1 and 5.1 occurred at the Obsidian Buttes, near the southern San Andreas Fault. The earthquake swarm shook the nearby town of Brawley with the USGS attributing the temblors to faults in the Brawley Seismic Zone. In September, a sulfurous stench emanated from the Salton Sea and wafted across the Inland Empire. The odor was tentatively linked to a fish die-off, but could also have been caused by volcanic gases.

These are not impressive volcanoes nor is this a glamorous part of California but for me that is exactly why it should be brought to peoples attention. Perhaps the biggest risk here is from earthquakes but there may well be a large source of Magma which would make me nervous.


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  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

What a fascinating read, Brick. Thank you for going to the effort of writing about this. I will keep an eye on this area for activity on my earthquake apps.

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