No Tsunami Threat To Guam From Earthquakes In Micronesia Friday

Two earthquakes above magnitude 6 hit Micronesia on Friday, Dec. 8.

The U.S. Geological Survey recorded an earthquake with a magnitude 6.5 earthquake in Micronesia at 10:22 a.m.

The earthquake was centered 33 miles northwest of Fais, Micronesia — about 385 miles southeast of Guam — at a depth of 8.5 miles, the U.S.G.S. stated online.

At 7:51 p.m. the same day, a magnitude 6.4 earthquake struck 155 miles east-northeast of Yap and 380 miles southwest of Guam. The quake struck at a depth of 39 mile.

There were no threats of tsunamis from either quake. Three other quakes between magnitude 4.7 and 5.5 were also recorded in the region, according to the U.S.G.S. website.

6.0-Magnitude Quake Hits Off Papua New Guinea

A 6.0-magnitude earthquake struck just off the coast of Papua New Guinea Friday, US seismologists said, but there were no immediate reports of damage and no tsunami warning was issued.

The quake hit at a depth of 52 kilometres (32 miles) about 59.1 kilometres from the nearest town of Finschhafen in Morobe province, the United States Geological Survey said.

The quake struck within three kilometers of the shoreline, with the potential for damage up to 45 kilometers away, Geoscience Australia said.

“There is potential for some damage to the local towns,” Geoscience seismologist Eddie Leask told AFP.

“Magnitude 6.0 is reasonable in its shaking… so you do have high-energy shaking in the local areas that can cause some issues.”

Earthquakes are common in PNG, which sits on the so-called Pacific Ring of Fire, a hotspot for seismic activity due to friction between tectonic plates.

Quake Hits Southeast Iran, Destroys Homes; No Fatalities Reported

A strong earthquake of magnitude 6.0 struck southeastern Iran on Friday, injuring at least 42 people and destroying several homes in an area where most people live in villages of mud-walled homes. State media said no deaths had been reported.

Rescue workers, special teams with sniffer dogs and units of Iran’s Revolutionary Guards and Basij militia forces were sent to the quake-hit areas in Kerman province, Iran’s semi-official Fars news agency said.

State TV said many residents rushed out of houses in Kerman city and nearby villages and towns, fearing more tremors after some 51 aftershocks following the 6:32 am (0232 GMT) quake.

“The quake destroyed some houses in 14 villages but so far there has been no fatalities,” a local official told state TV. “Fortunately, no deaths have been reported so far.”

The quake struck less than three weeks after a magnitude 7.3 earthquake hit villages and towns in Iran’s western Kermansheh province along the mountainous border with Iraq, killing 530 people and injuring thousands of others.

The US Geological Survey said Friday’s quake, at first reported as magnitude 6.3, was centred 58 km northeast of Kerman city, which has a population of more than 821,000. The quake was very shallow, at a depth of 10 km, which would have amplified the shaking in the poor, sparsely populated area.

Head of Relief and Rescue Organisation of Iran’s Red Crescent Morteza Salimi told state television that at least 42 people were injured. Iran’s state news agency IRNA said most of those hurt had minor injuries.

“Assessment teams are surveying the earthquake-stricken areas and villages in Kerman province,” IRNA quoted local official Mohammadreza Mirsadeqi as saying.

Iran’s semi-official Tasnim news agency said the quake had caused heavy damage in Hojedk town and some villages were hit by power and water cuts.

State TV aired footage of damaged buildings in remote mountainous villages near Hojedk town, the epicentre of the earthquake with a population of 3,000 people. TV said coal mines in the area had been closed because of aftershocks.

Iran’s Red Crescent said emergency shelter, food and water had been sent to the quake-hit areas.

Criss-crossed by several major fault lines, Iran is one of the most earthquake-prone countries in the world. In 2003, a magnitude 6.6 quake in Kerman province killed 31,000 people and flattened the ancient city of Bam.

New Early Gravity Signals To Quantify The Magnitude Of Strong Earthquakes

After an earthquake, there is a disturbance in the field of gravity almost instantaneously. This could be recorded before the seismic waves that seismologists usually analyze. In a study published in Science on December 1, 2017, a team formed of researchers from CNRS, IPGP, the Université Paris Diderot and Caltech has managed to observe these weak signals related to gravity and to understand where they come from. Because they are sensitive to the magnitude of earthquakes, these signals may play an important role in the early identification of the occurrence of a major earthquake.

This work came out of the interaction between seismologists who wanted to better understand earthquakes and physicists who were developing fine gravity measurements with a view to detecting gravitational waves. Earthquakes change the equilibrium of forces on Earth brutally and emit seismic waves whose consequences may be devastating. But these same waves also disturb Earth’s field of gravity, which emits a different signal. This is particularly interesting with a view to fast quantification of tremors because it moves at the speed of light, unlike tremor waves, which propagate at speeds between 3 and 10 km/s. So seismometers at a station located 1000 km from the epicenter may potentially detect this signal more than two minutes before the seismic waves arrive.

The work presented here, which follows on a 2016 study which demonstrated this signal for the first time, greatly increases its understanding. First, the scientists did indeed observe these signals on the data from about ten seismometers located between 500 and 3000 km from the epicenter of the 2011 Japanese earthquake (magnitude 9.1). From their observations, the researchers then demonstrated that these signals were due to two effects. The first is the gravity change that occurs at the location of the seismometer, which changes the equilibrium position of the instrument’s mass. The second effect, which is indirect, is due to the gravity change everywhere on Earth, which disturbs the equilibrium of the forces and produces new seismic waves that will reach the seismometer.

Taking account of these two effects, the researchers have shown that this gravity-related signal is very sensitive to the earthquake’s magnitude, which makes it a good candidate for rapidly quantifying the magnitude of strong earthquakes. The future challenge is to manage to exploit this signal for magnitudes below about 8 to 8.5, because below this threshold, the signal is too weak relative to the seismic noise emitted naturally by Earth, and dissociating it from this noise is complicated. So several technologies, including some inspired from instruments developed to detect gravitational waves, are being envisaged to take a new step forward in detection of these precious signals.

Time Between World-Changing Volcanic Super-Eruptions Less Than Previously Thought

After analysing a database of geological records dated within the last 100,000 years, a team of scientists from the University of Bristol has discovered the average time between so-called volcanic super-eruptions is actually much less than previously thought.

Volcanoes and bolides, such as asteroids, are geohazards powerful enough to be destructive on a global scale.

One recent assessment described them as capable of returning humanity to a pre-civilization state.

The largest explosive eruptions are termed ‘super-eruptions’, and produce in excess of 1,000 gigatons of erupted mass, enough to blanket an entire continent with volcanic ash, and change global weather patterns for decades.

The team from the University of Bristol’s Schools of Earth Sciences and Mathematics estimated how often the largest explosive eruptions happen. Their analysis indicates that the average time between super-eruptions is only slightly longer than the age of our civilization — dating from the Agricultural Revolution 12,000 years ago.

Jonathan Rougier, Professor of Statistical Science, said: “The previous estimate, made in 2004, was that super-eruptions occurred on average every 45 — 714 thousand years, comfortably longer than our civilization.

“But in our paper just published, we re-estimate this range as 5.2 — 48 thousand years, with a best guess value of 17 thousand years.”

According to geological records, the two most recent super-eruptions were between 20 and 30 thousand years ago.

Professor Rougier added: “On balance, we have been slightly lucky not to experience any super-eruptions since then.

“But it is important to appreciate that the absence of super-eruptions in the last 20 thousand years does not imply that one is overdue. Nature is not that regular.

“What we can say is that volcanoes are more threatening to our civilization than previously thought.”

Our civilization will change in unimaginable ways over the next thousand years, and there are many other ways in which it might suffer a catastrophic blow well before the next super-eruption.

On that basis, Professor Rougier says there is little need to plan now for a super-eruption, especially with many other pressing issues to address, which will affect the current and the next generation of humans. But large eruptions, which are much more frequent, can still be devastating for communities and even countries, and careful planning is a crucial part of disaster risk reduction.

Regarding the paper, Professor Rougier explained: “As well as improving our understanding of global volcanism, our paper develops relatively simple techniques to analyse incomplete and error-prone geological and historical records of rare events.

“These difficulties are ubiquitous in geohazards, and we expect our approach will be used for reappraising other types of hazard, such as earthquakes.”

Magnitude 6.6 Earthquake Hits Near Australia

An earthquake of magnitude 6.6 has struck in the Pacific Ocean, 74km east of the Loyalty Islands, New Caledonia.

The quake struck at a shallow depth of 13.0 km on Sunday night (AEDT), the United States Geological Survey (USGS) said.

The Pacific Tsunami Warning Center said in a statement that a destructive Pacific-wide tsunami was not expected and there was no tsunami threat to Hawaii.

Magnitude 6.3 Earthquake Strikes Xizang-India Border

A early morning magnitude 6.3 earthquake jolted a remote corner of Tibet early Saturday, with no reported casualties. The China Earthquake Administration placed the epicenter at Nyingchi in China’s the Tibet Autonomous Region near China’s disputed border with India. The area is sparsely populated and known for its soaring Himalayan peaks and sacred Tibetan sites.

China’s official Xinhua News Agency reported that several homes were damaged but no casualties have been reported. A resident in Milin county who gave her surname as Ma said her family was in bed when they felt tremors lasting 30 seconds.

“We didn’t see people rushing out of their homes,” she said. “Everything is normal here.” Many local residents are celebrating a Tibetan New Year festival this weekend.