PLANETARY TREMORS: Strong 5.0 Magnitude Earthquake Strikes Off The Coast Of Mexico - USGS! [MAPS + TECTONIC SUMMARY]

USGS earthquake location.

March 5, 2016 - MEXICO - A 5.0-magnitude earthquake occurred on Saturday near the Mexican coast, in the southeastern part of the country, the US Geological Survey (USGS) reported.

The epicenter of the earthquake was located 46 kilometers (28.6 miles) southwest of the town of Tres Picos in Chiapas.

It struck about 80 kilometers (50 miles) deep, according to the seismologists. There were neither immediate reports of damage or casualties, nor a tsunami threat.

The last relatively deep earthquake occured near of Tres Picos in mid-December.

The seismologists initially measured the strength of the earthquake at 6.4 but later upgraded it to a significantly stronger 6.6 magnitude. - Sputnik.

Seismotectonics of Mexico

Located atop three of the large tectonic plates, Mexico is one of the world's most seismically active regions. The relative motion of these crustal plates causes frequent earthquakes and occasional volcanic eruptions. Most of the Mexican landmass is on the westward moving North American plate. The Pacific Ocean floor south of Mexico is being carried northeastward by the underlying Cocos plate. Because oceanic crust is relatively dense, when the Pacific Ocean floor encounters the lighter continental crust of the Mexican landmass, the ocean floor is subducted beneath the North American plate creating the deep Middle American trench along Mexico's southern coast. Also as a result of this convergence, the westward moving Mexico landmass is slowed and crumpled creating the mountain ranges of southern Mexico and earthquakes near Mexico's southern coast. As the oceanic crust is pulled downward, it melts; the molten material is then forced upward through weaknesses in the overlying continental crust. This process has created a region of volcanoes across south-central Mexico known as the Cordillera Neovolcánica.

USGS plate tectonics for the region.

The area west of the Gulf of California, including Mexico's Baja California Peninsula, is moving northwestward with the Pacific plate at about 50 mm per year. Here, the Pacific and North American plates grind past each other creating strike-slip faulting, the southern extension of California's San Andreas fault. In the past, this relative plate motion pulled Baja California away from the coast forming the Gulf of California and is the cause of earthquakes in the Gulf of California region today.

Mexico has a long history of destructive earthquakes and volcanic eruptions. In September 1985, a magnitude 8.1 earthquake killed more than 9,500 people in Mexico City. In southern Mexico, Volcán de Colima and El Chichón erupted in 2005 and 1982, respectively. Paricutín volcano, west of Mexico City, began venting smoke in a cornfield in 1943; a decade later this new volcano had grown to a height of 424 meters. Popocatépetl and Ixtaccíhuatl volcanos ("smoking mountain" and "white lady", respectively), southeast of Mexico City, occasionally vent gas that can be clearly seen from the City, a reminder that volcanic activity is ongoing. In 1994 and 2000 Popocatépetl renewed its activity forcing the evacuation of nearby towns, causing seismologists and government officials to be concerned about the effect a large-scale eruption might have on the heavily populated region. Popocatépetl volcano last erupted in 2010.

More information on regional seismicity and tectonics

- USGS.

PLANETARY TREMORS: Very Strong 6.6 Magnitude Earthquake Hits Off Jalisco, Mexico Coast - USGS! [MAPS + TECTONIC SUMMARY]

USGS earthquake location.

January 21, 2016 - MEXICO - A magnitude-6.6 earthquake struck well off the Pacific coast of Jalisco, Mexico on Thursday morning.

The quake initially registered at 6.9 in magnitude but was later downgraded to 6.6, according to the U.S. Geological Survey.

The quake struck at 10:07 a.m. PT and was centered 134 miles southwest of Tomatlan and 158 miles west of Cihuatlan, USGS said.

USGS shakemap intensity.

Jalisco's Civil Protection agency said via Twitter that it was monitoring the state's 125 municipalities to rule out any damage.

The U.S. National Weather Service's Pacific Tsunami Warning Center said the quake was not forecast to cause a tsunami. - ABC7.

Seismotectonics of Mexico

Located atop three of the large tectonic plates, Mexico is one of the world's most seismically active regions. The relative motion of these crustal plates causes frequent earthquakes and occasional volcanic eruptions. Most of the Mexican landmass is on the westward moving North American plate. The Pacific Ocean floor south of Mexico is being carried northeastward by the underlying Cocos plate. Because oceanic crust is relatively dense, when the Pacific Ocean floor encounters the lighter continental crust of the Mexican landmass, the ocean floor is subducted beneath the North American plate creating the deep Middle American trench along Mexico's southern coast. Also as a result of this convergence, the westward moving Mexico landmass is slowed and crumpled creating the mountain ranges of southern Mexico and earthquakes near Mexico's southern coast. As the oceanic crust is pulled downward, it melts; the molten material is then forced upward through weaknesses in the overlying continental crust. This process has created a region of volcanoes across south-central Mexico known as the Cordillera Neovolcánica.

USGS plate tectonics for the region.

The area west of the Gulf of California, including Mexico's Baja California Peninsula, is moving northwestward with the Pacific plate at about 50 mm per year. Here, the Pacific and North American plates grind past each other creating strike-slip faulting, the southern extension of California's San Andreas fault. In the past, this relative plate motion pulled Baja California away from the coast forming the Gulf of California and is the cause of earthquakes in the Gulf of California region today.

Mexico has a long history of destructive earthquakes and volcanic eruptions. In September 1985, a magnitude 8.1 earthquake killed more than 9,500 people in Mexico City. In southern Mexico, Volcán de Colima and El Chichón erupted in 2005 and 1982, respectively. Paricutín volcano, west of Mexico City, began venting smoke in a cornfield in 1943; a decade later this new volcano had grown to a height of 424 meters. Popocatépetl and Ixtaccíhuatl volcanos ("smoking mountain" and "white lady", respectively), southeast of Mexico City, occasionally vent gas that can be clearly seen from the City, a reminder that volcanic activity is ongoing. In 1994 and 2000 Popocatépetl renewed its activity forcing the evacuation of nearby towns, causing seismologists and government officials to be concerned about the effect a large-scale eruption might have on the heavily populated region. Popocatépetl volcano last erupted in 2010.

More information on regional seismicity and tectonics

- USGS.

PLANETARY TREMORS: Global Seismic Uptick - 6.3 Magnitude Earthquake Strikes Off the West Coast of Baja, California! UPDATE: Seismologist - The Powerful California Coast Quake Is "Unusual"?!

December 14, 2012 - UNITED STATES - Two violent earthquakes hit the southern cost of California this Friday morning at approximately 2:30 a.m. The first to hit was a 6.3 magnitude quake 262km SSW of Avalon, California the second quake was a 6.1 magnitude reading with an epicenter 142km SW of Avalon, California. The second earthquake was later downgraded to a 4.7 by the USGS. According to the U.S. Geological Survey, the Mag: 6.3 – Depth: 10 km – off the west coast Of Baja California – and the 4.7 magnitude earthquake. 175 km from Rancho Palos Verdes, CA, United States.

Witnesses in Anaheim say they felt a slow smooth whirlpool rolling shake. Another witness in Ocean Beach, San Diego, was quoted as saying “Been through many, this was the longest feeling one, my 2nd story 100 year old apt, the floor swayed and twisted. In Hillcrest they’re saying they felt a strong seemingly long quake. Inglewood says “It was crazy it didn’t wake me up but the dog did. Pico Rivera, say they felt a subtle sway and shake. Lamp and windows shook. Coronado witnesses say nothing fell off walls but certainly the house shook. here in San Diego, just felt my couch shaking from that quake a little while ago… very eerie! Folks in La Jolla say they felt a gentle shake. Spring Valley witness says it woke her up. An Anaheim witness told us she was awake for odd reason then started feeling the earthquake. She says it frightened. In her words: “I hope the world doesn’t really end. There were many more disturbed by these two quakes. Earthquake shaking in the eastern United States can travel much farther and cause damage over larger areas than previously thought, but these quakes were south west of that part of the U.S. U.S. Geological Survey scientists found that last year’s magnitude 5.8 earthquake in Virginia triggered landslides at distances four times farther—and over an area 20 times larger—than previous research has shown. There are no reports of damage or lost of life. While we were yet compiling this report another 5.1 quake hit the southern coast of California. - Guardian Express.

Seismotectonics of Mexico.
Located atop three of the large tectonic plates, Mexico is one of the world's most seismologically active regions. The relative motion of these crustal plates causes frequent earthquakes and occasional volcanic eruptions. Most of the Mexican landmass is on the westward moving North American plate. The Pacific Ocean floor south of Mexico is being carried northeastward by the underlying Cocos plate. Because oceanic crust is relatively dense, when the Pacific Ocean floor encounters the lighter continental crust of the Mexican landmass, the ocean floor is subducted beneath the North American plate creating the deep Middle American trench along Mexico's southern coast. Also as a result of this convergence, the westward moving Mexico landmass is slowed and crumpled creating the mountain ranges of southern Mexico and earthquakes near Mexico's southern coast. As the oceanic crust is pulled downward, it melts; the molten material is then forced upward through weaknesses in the overlying continental crust. This process has created a region of volcanoes across south-central Mexico known as the Cordillera Neovolcánica.

The area west of the Gulf of California, including Mexico's Baja California Peninsula, is moving northwestward with the Pacific plate at about 50 mm per year. Here, the Pacific and North American plates grind past each other creating strike-slip faulting, the southern extension of California's San Andreas fault. In the past, this relative plate motion pulled Baja California away from the coast forming the Gulf of California and is the cause of earthquakes in the Gulf of California region today. Mexico has a long history of destructive earthquakes and volcanic eruptions. In September 1985, a magnitude 8.1 earthquake killed more than 9,500 people in Mexico City. In southern Mexico, Volcán de Colima and El Chichón erupted in 2005 and 1982, respectively. Paricutín volcano, west of Mexico City, began venting smoke in a cornfield in 1943; a decade later this new volcano had grown to a height of 424 meters. Popocatépetl and Ixtaccíhuatl volcanos ("smoking mountain" and "white lady", respectively), southeast of Mexico City, occasionally vent gas that can be clearly seen from the City, a reminder that volcanic activity is ongoing. In 1994 and 2000 Popocatépetl renewed its activity forcing the evacuation of nearby towns, causing seismologists and government officials to be concerned about the effect a large-scale eruption might have on the heavily populated region. Popocatépetl volcano last erupted in 2010. - USGS.

WATCH: Seismologist - Powerful California Coast Quake Is "Unusual"?!

GEOLOGICAL UPHEAVAL: Scientists Find Violent And Weird Underwater Volcano Near Baja, California - Tectonic Forces Are Tearing the Earth's Crust Apart, Creating A Long Rift Where Magma Oozes Toward The Surface!

December 14, 2012 – CALIFORNIA , UNITED STATES - Scientists have discovered one of the world's weirdest volcanoes on the seafloor near the tip of Baja, Mexico. The petite dome — about 165 feet tall (50 meters) and 4,000 feet long by 1,640 feet wide (1,200 m by 500 m) — lies along the Alarcón Rise, a seafloor-spreading center. Tectonic forces are tearing the Earth's crust apart at the spreading center, creating a long rift where magma oozes toward the surface, cools and forms new ocean crust. Circling the planet like baseball seams, seafloor-spreading centers (also called mid-ocean ridges) produce copious amounts of basalt, a low-silica content lava rock that makes up the ocean crust.

These maps show the location of the Alarcón Rise, a 31-mile-long (50 kilometer) spreading center at
the mouth of the Gulf of California. Along ocean spreading ridges like the Alarcón Rise, the
seafloor is splitting apart as lava wells up from underneath. CREDIT: (c) 2012 MBARI.

But samples from the newly discovered volcano are strangely rhyolite lava, and have the highest silica content (up to 77 percent) of any rocks collected from a mid-ocean ridge, said Brian Dreyer, a geochemist at the University of California, Santa Cruz. The results were presented last week at the annual meeting of the American Geophysical Union. Researchers with the Monterey Bay Aquarium Research Institute (MBARI) discovered the volcano this spring, during a three-month expedition to the Gulf of California, the warm stretch of water that separates Baja from mainland Mexico. A remote-control vehicle explored the volcano, which is 7,800 feet (2,375 m) below the surface, and brought samples back to the ship. “When we picked up the rocks and got them back on the ship, we immediately noticed that they were very low density, and they were very light, glassy and gray.

 The high-resolution seafloor map above was compiled using data from MBARI's mapping AUV.
The red box outlines the position of the rhyolite dome. CREDIT: (c) 2012 MBARI.

They were not the usual dark, black, shiny basalts,” Dreyer told OurAmazingPlanet. “So we immediately knew that something was unusual.” The volcano is primarily rhyolite and a silicic lava called dacite, said MBARI geologist Jennifer Paduan. “To find this along a mid-ocean ridge is a total surprise,” she told OurAmazingPlanet. Boulders and blocks the size of cars and small houses littered the steep slopes of the dome, the robot's video camera showed. Of more concern is the evidence for explosive volcanism, which is typical of rhyolite volcanoes, Paduan said. “It's only 100 kilometers [60 miles] from land. When the sun is setting, you can see Cabo,” she said. Both the Baja Peninsula and mainland Mexico near Alarcón Rise have cities and luxury resorts. The Gulf of California is also home to endangered sea life. Rhyolite lava carries more gas and volatiles (things that are likely to cause explosions) than basalt, and when magma meets water, it vaporizes instantly, driving an even more explosive eruption.

“There's definitely explosive deposits there, and that is of extreme concern, given that the ridge is so close to land and the tsunami potential of a big explosion there,” Paduan said. “We don't know how explosive, and that is something we are definitely trying to figure out.” Rhyolites have been found on spreading centers, but only above hot spots, such as in Iceland and the Galapagos Islands, Dreyer said. Hot spots are plumes that bring magma to the surface from deep within Earth's mantle. There is no hot spot under the Alarcón Rise, he said. Rhyolite lava typically occurs only on continents, such as in Mount St. Helen's growing dome in Washington. One possible explanation for the bizarre composition of the Alarcón dome is that continental crust snuck into the molten rock below — the spreading center is young, and continental crust lies close by. But tests of different isotopes (versions of elements with differing numbers of neutrons in the cores) in the lava samples revealed no evidence of contamination by continental crust, Dreyer said. - Our Amazing Planet.