One piece of evidence that helped to establish the theory of Plate Tectonics in the early-1960’s was the recognition of patterns of magnetisation in the basalts of the seafloor that were symmetrical about the global oceanic ridge system. Fred Vine and Drummond Matthews recognised that this pattern had to be fixed in place as the lavas, that were erupted along the ocean ridge, cooled through ...[Read More]
One of the most rewarding parts of fieldwork on volcanoes is when the parts start to fit together, and hunches turn into firmer ideas. When piecing together ancient volcanic eruptions, the process often starts with the discovery of the trace of a new deposit in a road cut section. This might be something as simple as the appearance of a scruffy yellow or orange band that catches our eye as we pass ...[Read More]
Today sees the launch of a project that I have been working on for the past few months – with the release of a short YouTube animation which explores processes in subduction zones. This is a part of a larger-scale public engagement activity called OxfordSparks which has been coming together over the past eighteen months. This project has brought together a great creative team from across Oxf ...[Read More]
Santiaguito volcano, Guatemala, burst into life in 1922 and is now the second longest continuing eruption. It has outlasted both Stromboli (Italy) and Sangay (Ecuador), both erupting since 1934, and is only outdone by Yasur (Vanuatu), which has been erupting at least since 1774, when first visited by Captain Cook. These long-lived eruptions give us an unusual opportunity to use the slowly-extruded ...[Read More]
Over on her Georney‘s blog, Evelyn Mervine has recently posted a nice piece with some spectacular images of columnar jointing. This seemed like a good opportunity to dust off some field photos, with some more examples of polygonal joint sets in lavas from a variety of settings, to illustrate the diversity of forms that cooling-contraction joints may take in volcanic rocks. The first example ...[Read More]
November 7th marked the 175th anniversary of one of the largest earthquakes to have struck northern Patagonia. The earthquake, which is estimated to have had a magnitude of 8, had an epicentre close to Valdivia, and was accompanied by significant ground shaking and subsidence as far south as Chiloe island, and a major tsunami that reached Hawaii. The eyewitness reports of the time have been well ...[Read More]
As you may have heard by now, Santorini volcano has recently been showing some unrest. Of course, it has only just come to the attention of the media, some of which have taken things a little further than can be justified. But for those of us involved in the work, this is a story which has taken rather longer to piece together. In my own case, the story started 26 years ago this week, when I firs ...[Read More]
