What is an Intraplate Earthquake?

Schematic of location of Nov 30 Anchorage earthquake. Image courtesy Temblor.net

 

Intro:  I wrote this some 12 months ago, a couple months after our M7.1 intraplate earthquake here in Anchorage.  This seems a good time to revisit what happened and why.  As usual, there are more questions afterwards than before.  Cheers –

VOLCANO ARMCHAIR HIKING – A Christmas Special

Fujisan

You may be about 90 and no longer able to travel the volcanoes of the world; you may be a young student lacking the funds as well as the friends willing to climb your favourite volcano with you; you may be an inveterate couch potato, or, you just want to spend some relaxing armchair time during the holiday season – don’t despair!

Sent Ash Around the World – Volcán CEBORUCO, Mexico

View from Los Aguajes in the east of Volcán Ceboruco. (© Juan Castillo Campos, via mapio.net)

As so often, and generally without intention, I have hit upon yet another volcano that has all the trimmings of a beast but seems not really to be recognised as such. Up to a few years ago there have been very few studies to find out about the seismological and structural properties of the volcano. Volcán Ceboruco is considered among the five volcanoes with the highest risk in Mexico, and the second most active after Colima volcano in the western Trans-Mexican Volcanic Belt. Yet, scientists had to point out, in a 2016 study, “that every effort should be made to monitor its seismic activity”.

Volcanoes of Io – Part 2 – The Volcanoes

Galileo 1998 image of Io. This one shows two active plumes. Pillan Patera plume is at the upper limb of the moon. It is 140 km tall. Second active plume is Prometheus Patera center bottom near the terminator between dark and light

Volcanoes of Io – Part 1 – Introduction

Io. Orange is plume deposit around Pele Patera. Multiple patera and plains are visible. Note lack of impact craters meaning the moon is regularly resurfaced. Image courtesy NASA JPL via Sen.com

Volcanoes where we don’t expect them – GARROTXA VOLCANIC FIELD, NE Spain

Castellfollit de la Roca: The confluence of the rivers Fluvià and Toronell created this stunning geological monument between them: a 1 km long and 50 m high basaltic lava crag, consisting of two superimposed lava flows with columnar jointing. (© Nasobema lyricum 2006, via Wikimedia)

View to the north over the northern part of Garrotxa VF, with the town of Olot in the left middleground. In the background the snow covered Pyrenees can be seen. (© turismegarrotxa.com)

Today our fancy takes us to the NE of Spain. Just to the corner where the Pyrenees mountain range meets the Mediterranean Sea, to the province of Girona in Catalonia. For millions of us European tourists the Mediterranean Costa Brava with its golden beaches is a household name. As in so many other touristic spots in the world, one could ask, how many of the sun worshippers would have known that, some 60 km inland, there is a volcanic field to be visited?

Makushin Volcano, Alaska. The 9th Most Dangerous Volcano in the US?

Active fumaroles on Makushin Volcano from Dutch Harbor July 2018. Photo courtesy Abi Woodbridge, via AVO

NEMRUT DAğI* 🇹🇷 – ANOTHER CANDIDATE FOR A FUTURE “DECADE VOLCANO”?

View over the caldera of Nemrut Dağı. (© Emin Noyan; screengrab from GEarth photo)

The spectacular caldera of Nemrut Dağı: light snow cover enhances all the volcanic features inside. (NASA image ISS001-E-6354 taken on 2001.02.13)

Preliminary note:
I have started work on this post long before the latest unacceptable political developments, so, it is pure coincidence that it’s getting published just now. In the region around Nemrut Dağı live Kurdish, Turkish and Armenian people. I wish peace for them all – and hopefully, my post will inspire interest in this wonderful part of the world.

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Nemrut Dağı* volcano has so many interesting features within and outside its caldera that it would probably take a several-week-long holiday do visit and explore them all. It has produced many colourful layers in ignimbrites during its various, mainly Plinian eruptions, as well as lava domes and obsidian flows, open fissures, steam chimneys, lava caves, what have you. I think this will become my favourite volcano!

2007 – 2014 Uplift Episode at Laguna del Maule

Laguna del Maule Volcanic Complex. Image courtesy Sernageomin

Sitting on a Hot Blob – TECUAMBURROW (󠁧🇬🇹)

Tecuamburro volcano: View across Laguna Ixpaco towards the S, with the lava dome Cerro Peña Blanca in the background. (© Oscar Villarreal, via former Panoramio)

About everybody knows that Guatemala has three very active volcanoes: Fuego, Pacaya and Santa Maria’s dome Santiaguito – but did you know that a staggering 324 eruptive centers have been identified in that country?