Vanautu Earthquake, September 4, 2011: Magnitude 7.0 quake hits Tanna

Vanautu Earthquake Map, September 4, 2011

A powerful earthquake has struck the South Pacific island of Vanuatu on Sunday, the US Geological Survey (USGS) reported.

According to the USGS, the quake measured 7.0 magnitude on the Richter Scale and was 132.4 km (82.3 miles) deep. It centered at 122 km (75 miles) SSE of Isangel, Tanna, Vanuatu and jolted the area at 09:55:36 AM on September 24, 2011 (Vanuatu Time).

The Pacific Tsunami Warning Center said the quake did not generate a destructive tsunami.

There were no immediate reports of damage or injuries from the Vanautu quake.

Vanuatu sits on the "Pacific Ring of Fire", an geographic zone where seismic activities are frequently experienced.

Alaska Earthquake 2011: Magnitude 6.8 quake jolts Alaska

Alaska Earthquake Map, September 2, 2011 | USGS

A major earthquake with a preliminary measurement of magnitude 7.1 has jolted the remote portions of Alaska, the U.S. Geological Survey (USGS) reported Friday.

The USGS issued, then later canceled, a tsunami warning and also lowered the magnitude to 6.8.

The quake centered at 45 km (27 miles) Southwest of Amukta Island, Alaska, approximately half-way between Atka and Nikolski. The 35.5 km deep temblor hit the area at 10:55 UTC (01:55 AM, local time).

Almost half an hour later, an aftershock which measured 4.5 occurred, the USGS said. Earlier reports had it much closer to the surface.

There were no reports of damage or injuries from the quakes.

According to an Alaska Native News report, the area frequently experiences earthquakes "every day, although a majority of them have a magnitude less than this."

"There have been numerous earthquakes in the Alaska region in the past week with a majority of the larger ones taking place off-shore of Kodiak Island far out to sea. The last comparable earthquake of similar size occurred on June 23, 2011, at shortly after 6 in the evening and was located in approximately in the same place. It measured 7.2," the report added.

Earthquake in the Philippines, August 25, 2011 | 4.5-magnitude quake jolts Panay

A tectonic earthquake which registered a Richter Scale reading of magnitude 4.5 struck Panay Thursday morning, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported.

The red dot marks the epicenter of the August 25, 2011 Panay earthquake | Source: Phivolcs

According to Phivolcs, the quake centered at San Jose de Buenavista, Antique and has a depth of 16 kilometers.



The temblor was felt at the following intensities in the following areas:



Intensity IV - Valderrama, Antique



Intensity III - San Jose de Buenavista, Hamtic, Barbaza, Sebaste, Sibalom, Pandan, Culasi & Libertad Antique; Iloilo City



Intensity II - Bingawan, New Lucena, Oton, Leon, (Iloilo); Lezo, New Washington, Kalibo & Malay, (Aklan)



The were no immediate reports of damage to property or casualities from the quake.



Meanwhile, here are the Phivolcs description of the intensities above :



Intensity IV (Moderately Strong) - Felt generally by people indoors and by some people outdoors. Light sleepers are awakened. Vibration is felt like a passing of heavy truck. Hanging objects swing considerably. Dinner, plates, glasses, windows and doors rattle. Floors and walls of wood framed buildings creak. Standing motor cars may rock slightly. Liquids in containers are slightly disturbed. Water in containers oscillate strongly. Rumbling sound may sometimes be heard.



Intensity III (Weak) - Felt by many people indoors especially in upper floors of buildings. Vibration is felt like one passing of a light truck. Dizziness and nausea are experienced by some people. Hanging objects swing moderately. Still water in containers oscillates moderately.



Intensity II (Slightly Felt) - Felt by few individuals at rest indoors. Hanging objects swing slightly. Still Water in containers oscillates noticeably.

Virginia quake rattles Eastern US, Canada

Virginia quake map |  Source: USGS

The magnitude 5.8 Virginia quake on Tuesday was felt as far away as Canada, Michigan, Pennsylvania, Ohio, South Carolina, North Carolina, Georgia, Tennessee, Illinois, New York and Massachusetts, according to reports.

The quake, which had an epicenter located 14 km (9 miles) South Southwest of Mineral, Virgina, struck the area at 17:51:04 UTC (1:51 PM EDT) at a depth of 6 km (3.7 miles), the US Geological Survey (USGS) reported.

The intraplate earthquake reportedly was the strongest in Virginia's recorded history since 1897.

There are reports that many buildings were evacuated in New York and Philadelphia including the Capitol building and the Pentagon in Washington, DC.

The temblor reportedly caused some damage to the Pentagon, the Washington National Cathedral and the Ronald Reagan Washington National Airport. 

Civilians and military personnel evacuate the Pentagon after an earthquake on Tuesday. | Photo: Jason Graham

In Virginia, two nuclear plants were taken offline because of the quake. A couple of airports were also temporarily closed.

There were no immediate reports of casualties from the quake.

California earthquake more mellow than East Coast quake

California earthquake vs Virginia quake

Wondering why the 6.0-magnitude California earthquake in 2004 was felt only 200 miles away (as far away as San Francisco and Los Angeles) while the less powerful magnitude 5.8 Virginia quake last Tuesday felt as much as 500 miles away (as far north as Ottawa, Canada; as far south as Georgia, and as far west as Chicago)?

According to U.S. Geological Survey (USGS) seismologist Lucy Jones, it is because of the differing geologic conditions of these two areas.

"The crust out in the East Coast is older, colder and harder, and does a better job transmitting the energy. So it's felt over a much wider area," Jones told LA Times.

In contrast, Jones added that in California, "the bad news is we have a lot of faults. The good news is all those faults break up our rock. And just like a cracked bell doesn't resonate as well as a solid bell, our cracked-up crust [weakens] the waves as they pass through. It dies off pretty rapidly.
"But out there, the rocks are old and cold and hard, and do a lovely job of transmitting the energy," Jones said.

A USGS article had also explained the phenomenon.

"Western rock is relatively young, which means it absorbs a lot of the shaking caused by earthquakes. Thus, western earthquakes result in intense shaking close to the epicenter, but fade more quickly the farther the earthquakes travel.

"In the eastern United States, on the other hand, the rock is far older, and so earthquakes can have a much larger and more widespread impact. Earthquake energy can therefore spread farther and have a greater impact." USGS wrote.

4.9-magnitude earthquake hits Davao

After a 5.9-magnitude earthquake jolted Zambales earlier today which precipitated three (3) aftershocks, a tremor hit another Philippine province anew.

The red dot marks the epicenter of the July 26, 2011 Davao earthquake | Courtesy of Phivolcs

At 4:02 pm today (July 26, 2011), a temblor with measured a Richter Scale reading of 4.9 magnitude struck 56 km Northeast of Baganga, Davao Oriental, according to the bulletin released by the Philippine Institute of Volcanology and Seismology (Phivolcs).

The tectonic quake which has a depth of 22km was felt at Intensity III in Davao City, the Phivolcs bulletin said.

There have been no reports about damages from the recent quake as of this writing.