Monday, October 7, 2013

Shallow Ongoing Quake Swarm near Pisgah Crater, CA

Over the last several days there has been an ongoing quake swarm near California's Pisgah Crater in the Lavic Lake Volcanic Field. Magnitudes have ranged from less than 1.0 up to 4.3, and most are occurring at very shallow depths. While this may alarm some due to the proximity to the monogenetic Pisgah Crater, these quakes are purely tectonic and not volcanic in nature. The depths are far too shallow to be related to magma, unless there was already an eruption underway (which there is not).

The quakes however are close enough to the system to have an effect (if say, there was a magma chamber still laying around underneath the crust, which is a bit doubtful at this time).


Image of the Pisgah Crater area with the location of the quakes. Screenshot from Google Earth with USGS plugin. 
While normally I wouldn't even bother writing about this volcano (as it has not erupted in historical time, nor will it likely erupt int he near future), there has been some un-needed and unjustified hype about it due to some alarmist bloggers, namely some anonymous 'blogger' named "Dutchsinse", who regularly raises false alarms about this volcanic system. I can assure you, there is nothing now, or in the recent past, that suggests that this system is currently active at all. If in fact there was any reason for concern in the near future, you can rest assured that the USGS would absolutely be able to tell far in advance if magma was rising, and since we are talking about California, media coverage would be incredibly heavy.

In any case, earthquake swarms near the San Andreas fault are quite common, and California is criss-crossed by many other smaller faults with regular small to moderate activity. This is absolutely nothing new.

The area is however a beautiful place to visit if you have the time and the drive to go out that way, and it is certainly a cool sight to see 'fresh' looking lava flows much like you'd find in Hawaii's Kilauea volcanic system. If you'r in the area (or are ready for a read trip to basically nowhere) you can easily check out Pisgah Crater, and nearby Amboy crater, both of which are morphologically fresh and well-preserved monogenetic cinder cones. Monogenetic cones only erupt once, and typically never again.

If a new eruption were to occur at Lavic Lake, it would likely not be in the same location that it had erupted in before, and would create a new vent or vents.


Wednesday, September 25, 2013

7.0 Magnitude Quake Strikes Peru, Tsunami Warning Issued

A 7.0 magnitude quake has occurred along the subduction zone in northern Peru, along the Pacific Ring of fire. Nearby Holocene volcanoes are Sara Sara, Coropuna, Andahua-Orcopampa, Huambo, and Sabancaya. The nearest volcano is Sara Sara, which last had an eruption during the Holocene, but historical eruptions are uncertain at best. Ash layers in peat moss do suggest somewhat geologically recent activity. The nearest historical volcano is Andahua-Orcopampa, which according to the GVP had its last eruption in the early 15th century. Sabancaya has also shown recent unrest, but is pretty far from the epicenter.

The tremblor prompted officials to issue a tsunami warning for the South Pacific, which is probably out of an abundance of caution, rather than because a tsunami was generated.

Damage has been reported in nearby towns, however no deaths or injuries are yet apparent. 



Screenshot of Google Earth with USGS overlay, and shakemap.

Earthquakes of large magnitude are common in the region, and along the majority of the subduction zones of the Pacific Ring of Fire. Peru typically has several large quakes a year, as well as Chile, which had a magnitude 8.8 quake several years ago that created a small tsunami. By the time the tsunami reached the big island of Hawaii, it was only a couple of feet (if that) high, and created very little damage apart from knocking a few boats around. The tsunami from the 2011 Japan quake, in contrast, was generated by a magnitude 9.0 subduction quake, which was able to cause damage as far as Southern California in the US.

A 7.0 earthquake is unlikely to generate a significant tsunami.




Tuesday, September 24, 2013

7.7 Magnitude Quake Hits Pakistan

A very large and relatively shallow quake has hit Pakistan today, causing a lot of damage, and fatalities. The quake struck near the country's southern shore, near the town of Parwān, about 173 miles NW of Karachi. The quake was strong enough to be felt throughout the region from India, to Afghanistan, to South Eastern Iran.



Image of quake epicenter from Google Earth with USGS plugin.

The quake occurred along a meandering strike-slip type fault, which has the potential, much like California's San Andreas fault, to generate large quakes up to and possibly exceeding 8.0 in magnitude.

So far at least 5 fatalities have been reported, as well as damage to buildings in the area.



Image of the quake 'shakemap' (legend is at the top of the screen) detailing the strength of the quake in relation to its epicenter.

At this time, at least 5 large-ish aftershocks have struck NNE of the epicenter, ranging from magnitude 4.7 to 5.9. More aftershocks are likely to hit the area for a period of several days to several weeks.

It is also likely that the list of injured or dead may increase as more information becomes available. The area where the quake struck is remote with several large villages nearby, but no major cities, and this is the area where the shaking was most intense. If any significant updates develop, I will update this post.


*****UPDATE*****

The quake was apparently powerful enough to cause some land to uplift, and a 30-40ft high island was actually created off of the coast due to the uplift! The island is around 100 feet long, and about one mile off of the coast.

We also know now that the quake has unfortunately killed around 250 people. (correction, the toll is now at around 330 people, and there are approximately 445 injured at this time)... The area is populated densely, but the buildings are not modern in any sense of the word, some being made of stones and mortar.


Friday, August 30, 2013

7.0, 6.8 Quakes Strike Alaska's Aleutian Islands

A 7.0 Quake struck SE of Adak island in Alaska's Aleutian islands today, according to USGS. The quake was followed by several aftershocks, one of mag 6.6 in the immediate vicinity, and followed to the East by a 6.8 magnitude tremor. More aftershocks are likely to occur for a few days.



Google Earth/USGS image of quake location.


The initial 7.0 quake was at a depth of approximately 21.4mi. No tsunami was generated according to USGS/NOAA. This occurred along the Aleutian subduction zone, where larger quakes are quite common.

There are no major population centers near the earthquake epicenter, with the nearest populated location being Adak, a port city that serves fisherman/crabbers in the Bering Sea. No damage has been reported. 

Monday, August 19, 2013

Manam Volcano In Papua New Guinea Sends Ash 15,000 Ft Into The Air

Papua-New Guinea's island volcano Manam has had a very large eruption, sending ash some 15,000 feet into the air, according to John Seach, an Australian volcanologist and frequent source of news from the Southern Hemisphere's volcanoes. John Seach's Twitter feed said about 3 hours ago:


Since I am personally not into Twitter, I have not linked the exact feed, just provided a screenshot, but you can get John's info there. He's a good resource for eruptions the rest of the world doesn't really cover.


3D satellite view of Manam Volcano from Google Earth.


Manam volcano is one of Papua-New Guinea's most active volcanoes, typically erupting several timesa year. This is a larger explosion than normal, and has probably produced some amount of pyroclastic flow. The volcanic was previously inhabited, with sparse villages around the circumference near shorelines, which can still be seen on Google Earth, but no current population remains. The island was abandoned completely in 2004, when 9,000 resudents were relocated. It is unclear at this time what direction the pyroclastic flow (if any) or ashfall is going, but an eruption this large I am assuming might prompt an evacuation.

No other news outlets are covering this eruption as of yet. The only population statistics on the island can be found here. The government had recently updated its disaster preparedness plans due to the large amount of volcanoes both active and dormant in the vicinity. Manam volcano and Papua-New Guinea are part of the Pacific Ring of Fire, a 'ring' of volcanoes that spans the boundaries of the Pacific Plate.

The Smithsonian GVP characterizes the volcano as follows:

"The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys," regularly spaced 90 degrees apart, channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern and western sides. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE avalanche valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded at Manam since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas."