It’s Island Week 4 here at GSS, which means we’ll mostly be posting about Islands. For about a week.

On September 29, 2009, just south of the islands that make up the Independent State of Samoa in Polynesia, an earthquake measuring 8.0 on the Moment Magnitude scale occurred, which generated a tsunami that swept across the nearby islands killing at least 149 people.

Most of the victims were on Samoa itself, where reports of a wave between 3 and 10 metres have emerged. Many low-lying areas in the Samoan islands have been completely destroyed, including the Prime Minister’s home village of Lepa.

Several other Polynesian islands were affected including the Unincorporated U.S. Territory of American Samoa to the east, where they lost at least 25 people, and to the south Tonga, where 6 people are so far known to have died.

Just 16 hours after the Samoan tsunami, another large earthquake occurred just off the southern coast of Sumatra, Indonesia. This eruption registered a lower moment magnitude reading of 7.6, but even without a tsunami has still claimed at least 1,100 lives.

Separated by 9,749 km, these two earthquakes were unrelated. They also lie on separate faults; Samoa sits just north of the Tonga Trench, and Sumatra is located on one of the world’s most active fault lines, the Great Sumatran fault.

What the two earthquakes do share however, is that all the affected islands fall within the Pacific Ring of Fire, a 40,000 km long horseshoe-shaped region that is defined by a nearly continuous path of volcanic features, including 452 volcanoes. 75% of the world’s active and dormant volcanoes are located within the region, and together they are responsible for about 90% of the world’s earthquakes.

More information is available at Wikipedia about the 2009 Samoa earthquake, the 2009 Padang earthquake, and the Pacific Ring of Fire.

It’s Volcano Week 4 here at GSS. Volcanoes, about a week. You know the drill!

Japan’s Mount Fuji (Fuji-san) is one of the most iconic and best recognised of any of Earth’s volcano, and when GSS first launched we received many suggestions that we post it. Unfortunately Google’s imagery was fairly low resolution at the time.¹

Thankfully the current imagery is vastly improved, and with its famous snow-capped peak, the view of Mount Fuji from up here is absolutely stunning.

At 3,776 metres, Mount Fuji is Japan’s highest mountain by a good margin, and given how beautiful it is from ground-level, it’s perhaps unsurprising that Fuji is widely regarded with great national pride, and has so often been a subject of Japanese art.

Although it hasn’t erupted since 1708, Mount Fuji is considered “active”², albeit with a low risk of eruption. For the sake of any occupants of all the buildings perched around the crater, I hope the volcanologists are right.

These buildings aren’t permanently occupied however, as they mostly exist to service the needs of the 200,000 people who climb Mount Fuji every year. Paved roads run to 2300 metres, from where the summit can be reached in 5 to 7 hours.

As I write this Wikipedia is having technical issues, but they do have a page about Mount Fuji. If you’re interested in climbing it yourself, Japan Guide has the full breakdown of how to go about it.

Thanks to (deep breath) Adam, hito, Ben, Jacek Fedorynski, Anne Mathews, Caius Toneriko, Jared, Eric, Ron Vogel, Roy Tanaka, Chris Palmieri, Planck, Ramsey Callaway, Matt Van Pelt, Corey, Colin Allen, TSG, Eitan Nudel, Fero GUNIC, Adrian Ward, Boniface, numlok, Tom Grusendorf, ian, Jerry Mills, Manuel Fernandez, Phillip Lockwood-Holmes, Dan, Turtleknee, TomG and Alfred.

It’s Volcano Week 4 here at GSS. Volcanoes, about a week. You know the drill!

Volcanoes probably aren’t the first thing you associate with Ethiopia, but Erta Ale is a particularly fine specimen.

It may only be a little over 600 metres high¹, but this volcano (whose name means “smoking mountain” in the local Afar language) is home to a fiery lake of lava – one of only five in the world! Little wonder that it is known locally as the “gateway to hell”. Living near here seems a risky proposition – a large eruption in 2005 killed hundreds of livestock and forced villages to be evacuated, and further eruptions two years later also caused hundreds of residents to flee.

Erta Ale is located in the Afar Depression, which is very geologically active: three “rift zones” (where tectonic plates are being forced apart) meeting nearby. As well as several volcanoes, there’s a multitude of hot springs and incredibly salty lakes.

Just below Erta Ale is the strikingly blue Lake Afrera, which is believed to contain at least 290 million tons of salt, but pales in comparison to Lake Assal, across the border in Djibouti. Assal is the saltiest lake on Earth², with a salinity 10 times greater than that of the ocean.

The region has another red-hot claim to fame. Even away from the boiling lava, it is said to be the hottest place on Earth, in terms of yearly average temperature. The mining community of Dallol (near the volcano of the same name) recorded a mind-boggling average temperature of 34°C between 1960 and 1966, although today it is a ghost town.

The BBC website has an interesting article on the challenges of surveying Erta Ale, including a video of one of the scientist abseiling into the crater. There’s more about the volcano at Wikipedia.

It’s Volcano Week 4 here at GSS. Volcanoes, about a week. You know the drill!

Newberry Volcano is an immense shield volcano located in central Oregon. In addition to a main volcanic caldera, the system is composed of many domes, cones, craters and lava flows across an area more than 32km in width in addition to two large fissures which extend outwards a considerable distance.

The central caldera, known as Paulina Peak, was created over hundreds of thousands of years and many eruptions; it now contains a pair of lakes fed by hot springs – Paulina Lake and East Lake. Extreme temperatures have been recorded beneath the caldera, leading to exploration with a view to creating geothermal power. The lava flow to the south of the lakes is known as Big Obsidian Flow.

Newberry Volcano is noted for creating many different types of lava, with a corresponding variety of landscape features being created as a result. The entire system is protected as the Newberry National Volcanic Monument. Apollo-era astronauts trained in areas of the volcano that resemble the moon’s surface.

Some of the most prominent features are buttes – tall cinder cones which result from a single eruption, including this cluster north of the lakes.

One of the most prominent is Lava Butte, which is approximately 150m tall, and has the Lava Lands Visitor Center at its base. Lava Butte is visible in a quite scenic Street View image from nearby Highway 97 … though it appears to have been so cold that one of the camera lenses froze over!

There are three large lava fields (mostly flat areas of volcanic rock) to the southest of the caldera – Devil’s Garden, Squaw Ridge and Four Craters. Extending from the edge of the latter is the imaginatively-named Crack-in-the-Ground, a 20m deep and 3km long fissure which is popular with hikers.

Equally creatively-named are the two nearby large maars, or explosion craters – Big Hole and Hole-in-the-Ground.

It’s Volcano Week 4 here at GSS. Volcanoes, about a week. You know the drill!

Rising up from the pastoral plains of Luzon Island in the Philippines is Mount Mayon, an active 2,400 metre-high stratovolcano. Known as the “perfect cone,” Mayon Volcano looks surreal in its symmetry, a true masterpiece of nature.

The volcano rises up in stark contrast to the surrounding flat terrain, its upper slopes averaging a 35-40 degree grade. Eruptions occur primarily from a small volcanic crater but have also created pyroclastic flows that carved over 40 ravines around Mayon’s cone. Viewing Mt. Mayon in Google Earth shows its unique shape:

With 47 eruptions since 1616, it is the most active volcano in the Philippines and remains a danger to nearby villages even today. Its deadliest eruption took place in February of 1814 and killed over 1,300 people. During that Pompeii-style eruption, Mayon Volcano reportedly spewed plumes of hot ash while fast-moving lava flows completely covered the village of Cagsawa. The town’s bell tower was the only structure left standing after the eruption had ended.

In recent decades, Mayon Volcano has continued to make its presence known in the region. With eruptions in 1984, 1993, 2006, and 2008, the residents of nearby towns and villages have become accustomed to frequent evacuation warnings and safety alerts. If you’re one of those adventurous¹ types who likes a steep uphill climb, try Mount Mayon, but be sure to wear a helmet and watch for falling debris and hot magma.