Wednesday, 1 April 2020

Slow Earthquakes

Slow Earthquakes

I had heard of such things but did not know much about them, so I was interested in reading THIS ARTICLE. After reading the article I realise that calling them earthquakes is dramatising something with no drama at all! 

An earthquake releases a lot of energy very quickly. A "slow earthquake" can release the same amount of energy but over a period of months or even longer. Is a slow earthquake somewhere between rocks moving steadily and moving in earthquakes? Can a slow earthquake trigger a catastrophic one nearby?

What makes an area have slow earthquakes rather than a catastrophic one? The author (from Cardiff) has been working in New Zealand where the Hikurangi subduction zone off the south eastern coast of the North Island demonstrates slow earth earthquakes in a conveniently shallow and accessible place. 

He hypothesises that the very variable seafloor rocks and sediments may have something to do with it. Also the presence of seamounts, pressurised fluids decreasing frictional resistance, seafloor roughness and other things might be involved. Obviously we are in a phase of looking for a cause.




Out and About - on Mars

Out and About - on Mars

A correspondent emailed me THIS LINK and it is wonderful. I make a lot of panoramas with my photos but they pale in comparison (on at least two levels - quality and location!) with this one. Look on it and wonder!



Wednesday, 25 March 2020

DOWN TO EARTH EXTRA - April 2020


DOWN TO EARTH EXTRA - April 2020


You can get the latest edition HERE




At this Moment of Crisis........

At this Moment of Crisis........

Several correspondents have brought the following to my notice.


I think it originated on EPOD, which contains much of interest.

Diamonds Make a Craton Bigger

Baffin Island Kimberlites and the North Atlantic Craton

A correspondent has brought THIS ARTICLE to my attention. Researchers working on kimberlites in southern Baffin Island found that wall rocks brought to the surface by the kimberlites bore evidence that they were part of the North Atlantic Craton. 

This increases the craton's size by 10%. You can find more from HERE, and for the truly dedicated HERE. If you are dedicated and solvent and want to investigate further look HERE

Geologists studying rock samples from Baffin Island find lost fragment of continent. Photo: istock.

Saturday, 21 March 2020

23rd to 29th March 2020


NEXT WEEKS EVENTS


23rd to 29th March 2020


THE FOLLOWING IS AN EXTRACT FROM BRISTOL AND WEST COUNTRY GEOLOGY CALENDARS


MORE DETAILS CAN BE FOUND IN THE BRISTOL AND THE WEST COUNTRY CALENDARS AND ON THE WEB SITES OF THE RELEVANT SOCIETY OR ORGANISATION.


Nothing Happening!

Blame the Virus
and wash your hands!


If you know of any events, let me know.



Saturday, 14 March 2020

16th to 22nd March 2020



NEXT WEEKS EVENTS

16th to 22nd March 2020


THE FOLLOWING IS AN EXTRACT FROM BRISTOL AND WEST COUNTRY GEOLOGY CALENDARS

MORE DETAILS CAN BE FOUND IN THE BRISTOL AND THE WEST COUNTRY CALENDARS AND ON THE WEB SITES OF THE RELEVANT SOCIETY OR ORGANISATION.


MONDAY 16TH

Geostudies Lecture Course - Germany
When
Mon, 16 March, 19:30 – 21:30
Where
Wynstones School, Stroud Road, Whaddon, Gloucester (map)
Description
The Geology of Germany 

 Monday 13th for 10 weeks (not 17th Feb) until 23rd  March. Held at Wynstones School, Stroud Road, Whaddon, Gloucester from 7.30 - 9.30pm on Mondays. 

Like Britain, Germany consists of a number of exotic Terranes, derived from different continents and amalgamated together by plate tectonic collisions. Northern Germany is part of Avalonia, which amalgamated with the East European Craton (Baltica) along the Tornquist suture in the east. A great deal of this area is plastered by thick Quaternary glacial sediments. 

Central Germany is part of Armorica, which collided with the north during the Variscan orogeny. There is, in places, thick Mesozoic unconformable cover. The extreme south is part of the Alpine orogeny, but its effects were transmitted northwards to affect and reactivate older structures. There was extensive volcanic activity during the Tertiary, and some famous asteroid impact sites. 

Cost £75
-----------------------------------------------

Teme Valley G S - Lecture
When
Mon, 16 March, 19:30 – 21:00
Where
Martley Memorial Hall B4197 by Sports Ground (map)
Description
Richard Edwards, The Japanese Island Arc:Perspectives on the Malvern Complex and Warren House Formation  

tuesday 17th


wednesday 18th


thursday 19th

Thornbury Geology Group, 7.30pm, The Chantry, Thornbury
When
Thu, 19 March, 19:00 – 21:30
Description
Thornbury Geology Group, 7.30pm at The Chantry, Thornbury, and every 3rd Thursday in the month.  

friday 20th


saturday 21st

South Wales G A - Lecture and AGM
When
Sat, 21 March, 10:30 – 12:30
Where
Lectures at University of Wales Swansea are held in the department of Geography in the Wallace building. We meet on the landing area inside the main entrance to the building for refreshments with lectures in the main lecture theatre. (map)
Description
AGM and retiring President's Address


sunday 22nd