Showing posts with label Earthquakes. Show all posts
Showing posts with label Earthquakes. Show all posts

Volcano Blows In Nicaragua, Thousands Evacuated

San Cristobal spews ash, 8 Sept.  2012
(photo Confidencial/ Tierrapinolera/
Ricci Rich Silva;
via The Nicaragua Dispatch)
Sept. 9, 2012 - Nicaragua's tallest mountain, San Cristobal, erupted three times early yesterday morning. The 5,725-foot (1,745-meter) volcano spewed a huge ash cloud and deadly gases over two miles (five kilometers) into the atmosphere and forcing the evacuation of at least 3,000 people, possibly as many as 5,000.

San Cristobal (also known as "El Viejo") is located about 95 miles (150km) north of Nicaragua's capital city Managua and is one of 19 active volcanoes in the Central American country.

The massive 7.6 earthquake in neighboring Costa Rica on Sept. 5 could have helped to rekindle San Cristobal. That quake has a lot of volcano watchers in the region worried.

Officials are also keeping a close watch on four active volcanoes in neighboring Costa Rica after its 7.6 quake.

"Even a small shift under one of these giants could cause an eruption," notes D. Chandler at The Guardian Express. "At least four of the seven active volcanoes in [Costa Rica] are in the crosshairs of scientists after the earthquake of 7.6magnitude occurred on Wednesday..."











TGE also reports that
"it is normal that volcanic structures, especially those already vulnerable, are affected. There is a rearrangement of material and even chemical changes," according to scientists who specialize in volcanic and seismic studies.

Meanwhile, Nicaragua is bracing for another killer earthquake of its own.  It seems inevitable, actually, and could happen literally any minute now.  "In the past 127 years, Managua has been destroyed three times by a major earthquake that strikes every 40-45 years. It’s been 40 years since the last one," notes The Nicaragua Dispatch. With 19 active volcanoes, the thought of a devastating earthquake is made more frightening by the possibility of lava and hot gases flowing down on the rubble - and struggling survivors.

Related:

MASSIVE 7.3 EARTHQUAKE PROMPTS INDONESIA TSUNAMI WARNING

Topographic map of Sumatra. Created with GMT f...Image via Wikipedia
January 10, 2011 - SUMATRA, INDONESIA - An early morning earthquake measuring Magnitude 7.3 struck Sumatra at 1:36 AM (Jakarta time; Tuesday, January 10, 2012 at 6:37 PM UTC), prompting a tsunami warning for Indonesia. The tsunami warning has since been cancelled

The M7.3 quake's epicenter was off the northern coast of the Indonesian island of Sumatra, about 423 km (262 miles) southwest of Banda Aceh, Sumatra, Indonesia. The quake was centered 29.1 km (18.1 miles) beneath the ocean floor. The coordinates of the epicenter: 2.396°N, 93.175°E.

The U.S. Geological Survery (USGS) reported that the earthquake off the west coast of northern Sumatra, Indonesia, "occurred as a result of strike-slip faulting within the oceanic lithosphere of the Indo-Australia plate, approximately 100 km to the southwest of the major subduction zone that defines the plate boundary between the Indo-Australia and Sunda plates offshore Sumatra. At the location of this earthquake, the Indo-Australia plate moves north-northeast with respect to the Sunda plate at a velocity of approximately 52 mm/yr. While rare, large strike-slip earthquakes are not unprecedented in this region of the Indo-Australian plate. Since the massive M 9.1 earthquake that ruptured a 1300 km long segment of the Sumatran megathrust plate boundary in December of 2004, two Mw 6.2 strike-slip events have occurred within 50 km of the January 10 2012 event, on April 19 2006, and October 4 2007. These events seem to align with fabric of the sea floor in the diffuse boundary zone between the Indian and Australian plates."  More info at USGS site.

Yesterday, we noted the M5.1 quake that hit off the northern coast of Papua, Indonesia.
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M7.7 Earthquake Hits Missouri, Tennessee, Arkansas, Kentucky, Felt in Boston and D.C.

December 16, 1811 - New Madrid, Missouri - The ground shook violently at approximately 2:15 a.m.today in this small town along the Mississippi River.
Early reports indicate that there was only minimal damage to buildings no known deaths in the sparsely populated area of southeastern corner of the state. The shaking was felt widely throughout the region. New Madrid resident Eliza Byran told The Southeast Missourian newspaper that the quake woke her up. She said it sounded like "loud but distant thunder, but more hoarse and vibrating, which was followed in a few minutes by the complete saturation of the atmosphere, with sulphurious vapor, causing total darkness."  
That's how the story might have been reported on the day that the New Madrid fault line buckled in late 1811. This Friday, December 16, 2011, is the 200-year anniversary of the what has come to be known as "the New Madrid Earthquake." There were actually three powerful quakes, however.  If - or when - the New Madrid fault line trips again the news would be much more grim because there is so much more development today. The town of New Madrid, MO was incorported in 1808, only three years before the earth shook beneath it.

Geological structure of Reelfoot Rift The U.S. Geological Survey (USGS) estimates that the first New Madrid quake on December 16, 1811  was a magnitude 7.7. That's huge, the biggest recorded in U.S. history.

The earthquake was felt widely over the entire eastern United States, says the USGS. "People were awakened by the shaking in New York City, Washington, D.C., and Charleston, South Carolina.

Perceptible ground shaking was in the range of one to three minutes depending upo the observers' location. The ground motions were described as most alarming and frightening in places like Nashville, Tennesse, and Louisville, Kentucky. Reports also describe houses and other structures being severely shaken with many chimneys knocked down. In the epicentral area, the ground surface was described as in great convulsion with sand and water ejected tens of feet into the air (liquefaction)."

The Southeast Missourian reports that there will be bicentennial anniversaries in 2012 on Jan. 23 and Feb. 7 for the subsequent two New Madrid quakes, which the USGS estimates measured at 7.5 and 7.7.

Accounts of the earthquakes from that time include newspaper articles that said the earthquakes were felt halfway across the country in Washington, D.C., and Boston, where the shaking caused church bells to ring. The USGS sums up the immense power of the powerful New Madrid quakes (my emphasis added):

The first principal earthquake, M7.7, occurred at about 2:15 am (local time) in northeast Arkansas on December 16, 1811. The second principal shock, M7.5, occurred in Missouri on January 23, 1812, and the third, M7.7, on February 7, 1812, along the Reelfoot fault in Missouri and Tennessee. 

The earthquake ground shaking was not limited to these principal main shocks, as there is evidence for a fairly robust aftershock sequence. The first and largest aftershock occurred on December 16, 1811 at about 7:15 am. At least three other large aftershocks are inferred from historical accounts on December 16 and 17. These three events are believed to range between M6.0 and 6.5 in size and to be located in Arkansas and Missouri. 

This would make a total of seven earthquakes of magnitude M6.0-7.7 occurring in the period December 16, 1811 through February 7, 1812. In total, Otto Nuttli reported more than 200 moderate to large aftershocks in the New Madrid region between December 16, 1811, and March 15, 1812: ten of these were greater than about 6.0; about one hundred were between M5.0 and 5.9, and eighty-nine were in the magnitude 4 range. Nuttli also noted that about eighteen hundred earthquakes of about M3.0 to 4.0 during the same period.  More at the USGS site.

Videos of Deadly 7.2 Quake in Turkey, 1000 Feared Killed; Death Toll Rising

Oct. 23, 2011 - Turkey - Videos Below - A late breaking report from CNN: "The U.S. Geological Survey initially reported the quake had a magnitude of 7.3, then revised it down to 7.2. Roughly 20 aftershocks rattled the region, one of the nation's poorest. The largest had a magnitude of 6.0 [later revised to 7.2]. Some 25 apartment buildings and a student dormitory collapsed in the town of Ercis on the north shore of Lake Van, the Turkish Red Crescent said." The earthquake struck near the town of Ercis,by Lake Van, at 10:41 AM GMT.

CNN quoted Turkish Prime Minister Recep Tayyip Erdogan as saying that 138 people are dead (as of 6:21 PM EST New York) and 350 people were injured in the earthquake. This is Turkey's most powerful quake in over 10 years. The death toll estimate is now feared to be over 1,000. Many are thought to be trapped in the rubble.

Photo Credit: REUTERS/Abdurrahman Antakyali/Anadolu Agency