5.6 Magnitude EQ – South Australia

At approximately 09:25:17 UTC on Friday, March 23rd, a 5.6 magnitude earthquake based on land struck at a depth of 10.7 km (6.6 miles) in the region of the South Australia, 217 km (196 miles) SSW of Alice Springs, Australia. Coords: 10.387°S, 161.262°E … (USGS)

According to Geoscience Australia, the initial arrival was from 09:25:44 – 09:29:14 (UTC).

Geoscience has the depth at 3 km at present. Australia itself does not run over any prominent fault lines, so earthquakes further inland, like this one, are a rarity, though not unheard of.

The epicentre itself was 370 kilometres west-north-west of Oodnadatta, near the Northern Territory-South Australian border.

…(Geoscience)

While we were gone…

A lot happened while we were down. Sunspot 1402 decided to show its strength as it crossed over the visible corona. From the start it began shooting out M class flares, and just as it was leaving it did the same. The strongest flare it released was an X5 class flare, which produced a large CME that mostly hit Earth. On top of several other C and M class flares, the magnetic field has had to work over time on certain occasions as of late.

The volcanic situation is interesting as always, with a few new candidates appearing on the scene, with a few old timers like Etna continuing on and on.

The largest earthquake we’ve seen since we’ve been gone was a 7.4 magnitude quake that struck Mexico on the 20th, following a 6.9 that struck Japan just a few days earlier, and prior to a 6.6 that struck PNG late on the 21st. The 188 day theory did not hold true, unfortunately. The idea was that there was a megaquake separated by a 7 mag quake in this pattern, since February 27, 2010. While we did have some 6 magnitude action and a 7.4, it still isn’t enough to say that this cycle held out. I think that it may be indicative of a pattern of movement roughly every 6 months or so, but rounding it down to the day, or hour, is likely to yield no real results. That’s all at present. The equinox has come, and now shall the colours of 2012 really start to come through.

– Admin

Volcano Watch: Kilauea Update for March 22, 2012

(Activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)

A lava lake present within the Halema’uma’u Overlook vent during the past week resulted in night-time glow that was visible from the Jaggar Museum overlook. The lake, which is normally about 90–115 m (295–377 ft) below the floor of Halema’uma’u Crater and visible by HVO`s Webcam, rose and fell slightly during the week in response to a series of large deflation-inflation cycles.

On Kilauea’s east rift zone, surface lava flows were active on the pali and upper coastal plain, in Royal Gardens subdivision, over the past week. As of Thursday, March 22, the flows were still more than 2 km (1.2 miles) from the coast, and there was no active ocean entry.

Two earthquakes beneath Hawai’i Island were reported felt this past week. A magnitude-2.7 earthquake occurred at 3:42 p.m., HST, on Monday, March 19, 2012, and was located 4 km (2 mi) southeast of Pu’ulena Crater at a depth of 2 km (1 mi). A magnitude-3.7 earthquake occurred at 00:04 a.m. (4 minutes after midnight) on Thursday, March 22, and was located 40 km (25 mi) west and offshore of Kailua-Kona at a depth of 33 km (21 miles).

…(Hawaii 24-7)

USGS reports quake near Wisconsin city plagued by booming sounds

People turn out to get their questions answered at a meeting with city officials about the mysterious booming and rumbling in Clintonville, Wis., Wednesday, March 21, 2012.

A minor earthquake occurred this week near the eastern Wisconsin city where researchers have been investigating a series of unexplained booming sounds, federal geologists said Thursday.

The U.S. Geological Survey said the 1.5-magnitude earthquake struck Tuesday just after midnight in Clintonville, a town of about 4,600 people about 40 miles west of Green Bay.

Geophysicist Paul Caruso told The Associated Press that loud booming noises have been known to accompany earthquakes. It’s possible the mysterious sounds that town officials have been investigating are linked to the quake, he said.

Earthquakes can generate seismic energy that moves through rock at thousands of miles per hour, producing a sonic boom when the waves come to the surface, Caruso said.

“To be honest, I’m skeptical that there’d be a sound report associated with such a small earthquake, but it’s possible,” he said.

Those reservations didn’t stop Clintonville City Administrator Lisa Kuss from declaring “the mystery is solved” at a news conference Thursday evening.

She said USGS representatives described the event as a swarm of several small earthquakes in a very short time.

“In other places in the United States, a 1.5 earthquake would not be felt,” she said. “But the type of rock Wisconsin has transmits seismic energy very well.”

The U.S. Geological Survey says earthquakes with magnitude of 2.0 or less aren’t commonly felt by people and are generally recorded only on local seismographs. Caruso said the Tuesday earthquake was discovered after people reported feeling something, and geologists pored through their data to determine that an earthquake did indeed strike.

Local residents have reported late-night disturbances since Sunday, including a shaking ground and loud booms that sound like thunder or fireworks.

City officials investigated and ruled out a number of human-related explanations, such as construction, traffic, military exercises and underground work.

Clintonville resident Jordan Pfeiler, 21, said she doubted an earthquake caused the noises. She said the booms she experienced were in a series over the course of several hours and not continuous as she might have expected if they were caused by an earthquake.

Still, she said, “It’s a little scary knowing Clintonville could even have earthquakes.”

Steve Dutch, a geologist at the University of Wisconsin-Green Bay, said a 1.5 magnitude earthquake produces the energy equivalent of 100 pounds of explosives and could produce loud sounds.

…(Washington Post)

Seismic swarm at San Salvador volcano alarms authorities

Authorities today ruled El Salvador declare an emergency for low-magnitude earthquakes that have shaken the Salvadoran capital, all centered in the San Salvador volcano, eight of them felt by the population and the strongest of 3.3 degrees on the Richter scale.

“There is no evidence that we are facing a potential emergency,” said Minister of Environment and Natural Resources, Herman Rosa Chavez, in a press conference in which he reiterated that no volcanic tremor, but tectonic.

“We did analysis of temperature in the area and there is no evidence that this is associated with volcanic activity, this has to do with the activation of local faults, which is something that happens and has happened before,” he said.

The eight tremors felt by the population have reached levels of between 2.2 and 3.3 degrees on the Richter scale, according to the National Service of Territorial Studies (SNET), which has recorded at least 25 microearthquakes.

The first quake was felt that reached 2.6 degrees and was registered at 01.22 local time (7.22 GMT), and most recently, of 2.7 degrees, at 15.50 (21.50 GMT).

The strongest earthquake of 3.3 degrees, occurred at 08.01 (14.01 GMT), said the SNET.

He added that the focal depth of earthquakes has fluctuated between 0.5 and 5.8 kilometers, so they felt in various parts of the city, near which is the San Salvador volcano, which is inactive.

Likewise, the eight earthquakes have reached an intensity of two on the Mercalli scale, whose maximum is 12, in San Salvador.

The Ministry of Environment and Natural Resources in a statement recalled that the last seismic swarm with epicenter in the San Salvador volcano was in 2007 when there were 142 microearthquakes, four of them felt by the population.

Apart from the string of earthquakes in San Salvador, today reported another quake Snet of 4.3 on the Richter scale at 11.26 local time (17.26 GMT) in Pacific Ocean, about 43 kilometers south of the estuary San Diego, in the department of La Libertad (center).

…(Univision)

Santorini: The Ground is Moving Again in Paradise

“After decades of little activity, a series of earthquakes and deformation began within the Santorini caldera in January of 2011,” said Newman, whose research is published by Geophysical Research Letters. “Since then, our instruments on the northern part of the island have moved laterally between five and nine centimeters. The volcano’s magma chamber is filling, and we are keeping a close eye on its activity.”

Newman, a geophysicist in the School of Earth and Atmospheric Sciences, cannot be certain whether an eruption is imminent since observations of such activity on these types of volcanoes are limited. In fact, similar calderas around the globe have shown comparable activity without erupting. However, Newman says the chamber has expanded by 14 million cubic meters since last January. That means enough magma has been pumped into the chamber to fill a sphere three football fields across.

Should Santorini erupt, Newman says it will likely be comparable to what the island has seen in the last 450 years.

“That could be dangerous,” notes Newman. “If the caldera erupts underwater, it could cause local tsunamis and affect boat traffic, including cruise ships, in the caldera. Earthquakes could damage homes and produce landslides along the cliffs.”

More than 50,000 tourists a day flock to Santorini in the summer months (from May to October). It’s common to see as many as five cruise ships floating above the volcano.

Santorini is the site of one of the largest volcanic events in human history. The Minoan eruption, which occurred around 1650 B.C., buried the major port city of Akrotiri with more than 20 meters of ash and created Santorini’s famous, present-day cliffs. Newman says such history will likely not repeat itself any time soon. Such an eruption comes along once every 100,000 years, and the current inflation in the magma chamber is less than 1 percent of the Minoan blast.

…(Science Daily)