**What counts is not necessarily the size of the dog in the fight - it's the size of the fight in the dog.**
Dwight Eisenhower
LARGEST QUAKES so far today -
5.2 SOUTHERN MID-ATLANTIC RIDGE
Yesterday, 6/19/14 -
5.2 OFFSHORE TARAPACA, CHILE
5.7 OFFSHORE TARAPACA, CHILE
5.8 OFFSHORE TARAPACA, CHILE
6.4 VANUATU
5.1 SOUTHERN SUMATRA, INDONESIA
Slow-Motion Earthquakes Caused by Natural Fracking? Natural fracking may be to blame for weird "slow" earthquakes that last for hours to days, a new study suggests.
Oil and gas fracking involves cracking open rocks using water laced with sand and chemicals, pumped underground at high pressure. Now, seismic evidence from the Cascadia subduction zone leads researchers to suggest a similar process takes place deep on the zone's massive fault, generating slow earthquakes.
Researchers only recently discovered slow earthquakes, and scientists are still figuring out how they work. These slow-motion quakes have been detected at subduction zones offshore of Japan, New Zealand, the United States and Canada. A subduction zone is a bang-up between two of Earth's tectonic plates, where a denser oceanic plate dives under a lighter continental plate.
Each subduction zone comes with its own puzzling pattern of repeating slow earthquakes. For Cascadia, the quakes strike every 14 months; in Japan, it's every six months, and New Zealand slips every two years. Based on the new study, the researchers think this pattern is linked to the amount of quartz dissolved in trapped water under pressure on the subduction zone fault. The trapped water (or fluid pressure) in small spaces in rocks lining the plate boundary builds up until it cracks open the fault, then the cycle repeats. Faults with more quartz (or silica) in their fluids will knit together more quickly, shortening the time between earthquakes.
When the Earth shifts during a quake, the pressure on the water drops nearly instantly. Then, the fluid pressure rebuilds until the next quake hits. The fluids come from the sinking oceanic plate. As it descends, the crust heats up, and fluids, such as seawater, escape and rise. The plate boundary traps the rising fluids, leading to increasing pore fluid pressure. Many other studies have noted high fluid pressure in zones where slow earthquakes occur.
Slow earthquakes unleash the same amount of seismic energy as regular earthquakes, but because the fault movements last for minutes to months, they cause no damaging shaking. These sluggish quakes also originate deeper on the fault than where faster temblors tend to strike. Scientists aren't sure if slow earthquakes can trigger deadly fast quakes, but many researchers are investigating the link between the two kinds of earthquakes.
"We don't know why there is a transition from regular to fast earthquakes, but that's really where the research is headed." The planet's biggest earthquakes strike at subduction zones, such as the magnitude-9.0 temblor in 2011 in Japan, and an estimated magnitude-9 along the Cascadia subduction zone on Jan. 26, 1700.
California - The Bay Area is due — some would say overdue — for a major quake. Planning scenarios typically put a large quake in the range of magnitude 6.8 to 7. This is based in part on the last big earthquake on the Hayward Fault, an 1868 event estimated to have been around 6.8. It’s possible that if the Hayward interacts with a fault like the nearby Rodgers Creek to the north, the resulting temblor might register closer to a 7.2.
It’s awful to consider the damage that might cause. The 1868 quake killed some 30 people, mostly from building collapse. But at that time Oakland was a town of 12,000 and there were only about 260,000 people living in the entire Bay Area; now there are more than 7 million, more than 2 million of whom live on or near the fault. “We’ve never had a major earthquake in a modern U.S. metropolitan area, and we don’t know what the results really will be.”
VOLCANOES -
In the past few months, Alaska’s seen a flurry of volcanic eruptions and sizable earthquakes. It’s disrupted life in the Aleutian Islands and the far western Brooks Range — and it’s got scientists wondering how all the activity might be connected.
Right now, five volcanoes in the Aleutian Islands are on alert. The Alaska Volcano Observatory says it’s THE MOST ACTIVITY THEY'VE SEEN AT ONE TIME in their 26-year history. “We’re as busy as we’ve ever been in terms of the number of volcanoes that are active in the state."
Only one of those has caused major disruptions so far — Pavlof Volcano sent up an ash plume and prompted days of local flight cancellations earlier this month. But volcanoes seem to be waking up all across the chain. Shishaldin, Cleveland and Veniaminoff in the eastern and central Aleutians have been on alert for months now. In the western Aleutians, the AVO put Semisopochnoi on watch just last week.
But does it mean there’s something causing all these flare-ups? Not necessarily. Scientific understanding of plate tectonics began evolving in Alaska with the 1964 Good Friday quake, and it’s still a work in progress. If there is something bigger going on, they can’t identify it — at least not yet.
That’s also true a thousand miles north of the Aleutians, where another seismic mystery has stretched across two months. Outside Noatak in the far western Brooks Range, there’s been a series of five earthquakes, each with a magnitude 5.7. The latest was on Monday. The Noatak quakes are too far away to impact volcanoes in the Aleutians. “Some of this is just a confluence of what really is day-to-day activity in Alaska."
But their grasp on that activity is, well, shaky. They know the basics: a tectonic plate in the region seems to be slowly pulling away from the continent. Normally, that would cause one large quake. Here it’s caused five smaller quakes instead. “You can think of this as the earth sort of inching along instead of doing it in one big movement."
Still, a 5.7 magnitude earthquake is nothing to scoff at. It shows up on seismic monitors around the world, including the 400 stations in Alaska. “We have never had a focus on Western and Northern Alaska, and I personally feel that’s a bit of a liability for the state. This sequence certainly indicates that there’s plenty of opportunity in these areas for earthquakes to intersect with populations.”
Alaskans live on volatile land. Quakes and volcanoes can damage property in the interior and interrupt air travel or set off tsunamis at sea. Even in remote towns, more monitors are always a good thing. Four of AVO’s on-alert volcanoes are repeat offenders with a long baseline of data. The fifth is more of an outlier. Semisopochnoi had been quiet since 1987 — the year before the AVO was formed – before it rumbled to life with a swarm of little earthquakes last week.
Since the island is so remote, they don’t know much about it. “It’s a volcano with a fairly violent past — it’s had a whole number of eruptions…. It’s actually a large caldera with a whole number of vents and very large lava flows that our geological investigations suggest are not that old. And we are currently watching it very, very closely, because the type of activity it’s experiencing is what you might see or might expect at a reawakening volcano.”
Hawaii - Is Mauna Loa volcano beginning to stir? The Hawaiian Volcano Observatory has recorded increased seismic activity on the flanks and summit of Mauna Loa over the past 13 months. Mauna Loa is the world's largest active volcano.
TROPICAL STORMS -
Current tropical storms - maps and details.
No current tropical storms.
SEVERE RAIN STORMS, FLOODING, LANDSLIDES -
Bulgaria floods: At least 10 killed in port city of Varna - The Black Sea town of Varna has received the equivalent of A MONTH'S RAINFALL IN 24 HOURS. At least 10 people have died and several are missing after torrential rain and heavy floods hit eastern Bulgaria.
Floodwaters in the Black Sea port city of Varna surged up to 1m (3.2ft). Many residents had to be rescued as cars were swept away. Hundreds have been left without electricity or food. There have been hailstorms and heavy rain in several parts of Bulgaria in recent days. Forecasts say the extreme weather is set to continue.
More bad weather is forecast for the end of the week. Forecasters said that the equivalent of a month's worth of rain fell in the regions of Varna and Burgas over the last 24 hours. "The tragedy is enormous. I am here on a street in the suburb of Aspruhovo. The street is not here, the houses are not here, there are cars on top of each other."
Fire-fighters in the town of Kilifarevo in central Bulgaria rescued 11 people from the tops of their houses. The flooding in Bulgaria follows on from similar deluges in the Balkans last month. Nearby Serbia and Bosnia were hit by THE WORST FLOODING SINCE MODERN RECORDS BEGAN. (photos and map at link)
Heavy rain this week pushing rivers out of their banks across Iowa - More rain was falling throughout the day in the flooded areas and their watersheds upstream.
Minnesota - More flooding. The Twin Cities and much of Minnesota continue to deal with the large amounts of rain that have fallen the last few days.
Illinois - More than 10 inches of rain fell in Dixon and west of Mendota just outside the Chicago area in 24 hours. A nearly stationary frontal boundary is to blame for the heavy rain and flash flooding that affected a large swath of real estate in northern Illinois.
Heavy rain hits Interior Alaska; rising rivers could cause minor flooding. The season's first big rainfall dumped more than 4 inches of rain on some parts of eastern Interior Alaska.
HEALTH THREATS -
RECALLS & ALERTS
Deadly pig virus cases in US projected to surge after summer - U.S. veterinarians are warning that outbreaks of a deadly pig virus will climb this autumn after a summertime hiatus, likely killing another 2.5 million pigs over the next 12 months and amplifying an increase in pork prices.
*****
Global Disaster Watch is on Facebook - with breaking news during the day.
