Hypo-theses

Nantwich Earthquake 31/01/2010

hypocentre — Tue, 02 Feb 2010 18:28:54 +0000

There was a small earthquake just south of Nantwich, Cheshire on January 31st, 2010 which we recorded here at Keele.

The earthquake magnitude has been determined by the Geological survey to be 1.3

The tremor is most likely related to subsidence or collapse due to dissolution of salt. The bedrock here is the Wilkesley Halite and in the Google Maps image of the earthquake location below salt dissolution features can be seen. A word of warning though as this location from the British Geological Survey is unlikely to be precise.

View Nantwich Quake in a larger map

Stoke-on-Trent Earthquakes Recorded at Keele

hypocentre — Thu, 28 Jan 2010 12:47:35 +0000

Two more small local earthquakes have occurred in Stoke-On-Trent following on from the two that happened on Christmas Eve and Christmas Day. Both were magnitude 1.8 and are probably related to old mine workings beneath the city.

View Stoke Quakes in a larger map

Using Gigapan and Photosynth in Geology Teaching

hypocentre — Fri, 22 Jan 2010 00:59:50 +0000

This week I presented some work in progress on the use of gigapan and photosynth to assist mobility impaired geology students at the “Overcoming Barriers to Learning in the Geosciences” meeting of the Geography, Earth and Environmental Sciences (GEES) subject centre of the Higher Education Academy (HEA).

The main aim of our MIS:TIQUE project (mobility impaired students : teaching in quite unsuitable environments) is to provide alternative technologies for mobility impaired students so that they can attain an equivalent learning experience to the able-bodied in geology fieldwork. Gigapan and photosynth allow us to mimic the observation patterns that we would like all students to use. This involves starting with an overview to develop hypotheses to what might be going on, moving in and around the outcrop to make more detailed observations and test the hypotheses, and then move back out again to revise the overview.

I’ve embedded the presentation below. Feel free to use any of the ideas but obviously if you use any of it please credit the source. If you have any questions, comments or feedback please use the blog comments. [Apologies for my powerpoint style - I tend to talk over images without using much text on the slides but this wouldn't make much sense in this context so I have added what I said to the images.]

igs_gees_overcoming_barriers

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Haiti Earthquake January 12, 2010 Recorded at Keele

hypocentre — Wed, 13 Jan 2010 08:59:38 +0000

Here is the seismogram of the M7 earthquake in Haiti on January 12, 2010 recorded at Keele University, UK.

This earthquake doesn’t appear to be that well recorded but the P and SS phases are identifiable.

The earthquake was a shallow left-lateral strike-slip earthquake along the Enriquillo-Plaintain Garden fault system, essentially a major component of the plate boundary between the North American and Caribbean plates. The Caribbean plate is moving eastwards with respect to North America by about 20 mm per year.

Much more on the tectonics of the area from Chris Rowan at Highly Allochthonous.

Recorded as part of the UK Schools Seismology project.

Rock365

hypocentre — Sun, 10 Jan 2010 20:44:47 +0000

In a moment of madness I have decided to embark on a flickr 365 project – to take a photograph every day for a year. What else would a geologist take for a theme for such an undertaking but rocks? So project Rock365 was born. I’m now ten days in and beginning to realise the enormity of what I have undertaken. Here are small versions of those first ten …

I’ve decided to put the images on my posterous stream as it is easier to update remotely than this blog. Chris Rowan has kindly added this to his allgeo geoblogosphere feed so you may have seen these already. They can also be found in my Flickr Rock365 set.

Ron Schott is doing something similar over on his Geology Home Companion Blog. Although his images aren’t necessarily being taken on that very day, his daily documentation of outcrops / deskcrops are much more detailed (and prettier) than mine.

I hope you drop by at hypocentre.posterous.com and enjoy a whole year’s worth of rock photos (if I can keep it going that long).

Stoke-on-Trent Christmas Earthquakes 2009

hypocentre — Fri, 08 Jan 2010 17:32:05 +0000

I was convinced that I felt an earthquake last night. I was just drifting off to sleep and must have drempt it as there was no record of our seismometer when I got into work this morning. However, in checking my iPhone for (non-existent) earthquake reports I did come across two local earthquakes that happened over Christmas whilst I was away in Morocco that I would have otherwise missed. This is quite a coincidence as I can’t remember any local earthquakes in nearly five years.

The first was on Christmas Eve, magnitude 2.1 and felt in Stoke-on-Trent, Staffordshire, UK, the second magnitude 1.7 on Christmas Day and not felt. Here are the seismograms recorded at Keele University on our School Seismology project seismometer.

When I first came to Keele University in the late 1980s, little did I realise the seismic activity of the area related to the area’s coal mining heritage. I have felt over a dozen local earthquakes over my time here.

Seismicity of Stoke-on-Trent after BGS Geoindex

Since the latter part of the nineteenth century several areas in North Staffordshire have experienced occasional series of Earth tremors which are known locally as ‘goths’ or ‘bumps’.

Between early 1975 and August 1997 the Hanford and Trent Vale areas in the southern suburbs of Stoke-on-Trent over 50 events were felt, the largest being a magnitude 2.8 event on 15th July 1975 which caused some local damage. The earthquakes were associated with the extraction of the Ten Feet seem which was mined between 1973 and 1977 from the Wolstanton pit. Activity centred on the region above the face and the pillars of adjacent seems. Events could not be correlated with any of the major or minor geological faults in the area.

Swarm activity started again in May 1980. Activity was located in two centres, one near Cobridge, the the Banbury seem was being worked, and one near Talke, where no mining was currently ongoing. 11 events were felt during this period including the magnitude 3.3 Talke Pits event on 9th November 1980, the largest local event felt in recent times.

Between 1982 and 1987 activity in the region was very low, although the Lleyn Peninsula earthquake on 19th July 1984 was felt strongly in Staffordshire. On 2nd July 1987 an earthquake was felt in the Hanley region. A series of events the occurred in the Smallthorne district over the next few years culminating in a magnitude 3.0 earthquake on 4th March 1990. A month later, on 2nd April the Bishop’s Castle earthquake (magnitude 5.1) in the Welsh borders was felt strongly across the region.

Two swarms of earthquakes became active in February 1995. Initial activity was located between Wolstanton and Cobridge and started with a magnitude 2.5 earthquake on 20th February with six felt events and 108 recorded at Keele in a week. Activity decreased after the 26th April 1995 magnitude 1.4 event but recommenced in May 1966 with a series of four earthquakes including a felt magnitude 2.8 on 6th May.

A second swarm became active two days after the first on 22nd February 1995 located south of Newcastle-under-Lyme with an initial event of magnitude 2.3. Five events at sporadic intervals were felt. Events in this second area show typical characteristics of mining induced earthquakes with a clear rise in activity during the working week and a decrease at weekends. There was a period of quiesence after the magnitude 2.3 event suggesting that this had released a significant amount of the local stress, sufficient to halt local activity for a week.

Also felt in Staffordshire during this period was a magnitude 3.4 earthquake near Shrewsbury on 7th March 1996

Activity in the area south of Newcastle-under-Lyme, between Whitmore and Keele recommenced between October 1997 and April 1998 with numerous felt events, the largest being around magnitude 2. Activity largely ceased in this area towards the end of 1998 with the closing of the Silverdale Colliery. An earthquake of magnitude 2.8 occurred on September 7, 1999 about 1.5 km southwest of the previous mining induced events and a magnitude 2.4 occurred in the same Whitmore Wood area on October 2, 1999.

On the 2nd January 1996 two tremors struck Kidsgrove, the latter causing minor damage. There was also a magnitude 2.8 event on May 6, 1996 in Cobridge that was felt across North Staffordshire. Further Cobridge earthquakes happened on August 9, 1998 and February 24, 2000 (1.7 magnitude).

February 22 to March 10, 2003 saw a series of six earthquakes near Whitmore with magnitudes between 1.3 and 2.3. The last earthquakes prior to the recent Christmas 2009 events occurred in the Wolstanton-Cobridge area on June 8, 2005 with a magnitude of 2.6.

The Dudley (September 22, 2002) and Market Rasen (February 27, 2008) were felt in the region.

Reference: Recent Seismicity in the Stoke-on-Trent Area, Staffordshire. British Geological Survey Technical Report WL/97/27 1997. J.H. Lovell, P.H.O. Henni & G.D. Ford (BGS), C. Baker, I.G. Stimpson & W. Pettitt (Keele University)

That was the year that was – 2009 Part Two

hypocentre — Mon, 21 Dec 2009 00:12:15 +0000

Continuing my photographic review of the year following on from Part 1 …

July saw the start of working on the Staffordshire Strategic Stone Study which has seen me spend the summer traversing the county looking at various building stones. This has included visits to two quarries that have provided much of Staffordshire’s building stone, Grinshill in Shropshire and Hollington in Staffordshire.

August saw the garden bloom in what little we had of a summer …

… and an evening field trip to Ossum’s Hill to see a new exposure of the bioclastic Carboniferous Limestone.

In September the study of Staffordshire Stone continued. Here is Mow Cop ‘Castle’ (actually a summerhouse) built on the edge of a Chatsworth Grit quarry.

I also visited Ireland for the EAGE Near Surface Geophysics conference and had a visit to the Tara zinc and lead mine.

Returning from Ireland, I spent a weekend in London.

After a day in the city, I spent a day down at Kew Gardens

October saw a visit to the National Arboretum at Westonbirt.

Finally, in November I was involved in some site clearance along the Hamps and Manifold Geotrail.

I’ve still got one major trip to do this month, more details in the New Year.

If you like my photographs have started a photostream that you can see on fluidr or flickr.

I’m also considering a ‘deskcrop365′ project with a new rock picture every day. If it happens then it will most likely appear on flickr and/or posterous.

It just remains for me to thank you for reading in 2009 and I hope to see you again in 2010.
Happy New Year

That was the year that was – 2009 Part One

hypocentre — Sun, 20 Dec 2009 00:18:52 +0000

In a fashion, after Sciencewoman, Tuff Cookie, Callan and Silver Fox, here is the first part of my personal photographic review of 2009.

January came and went, unnoticed. In February I did a guided geological walk for the residents of Maer, Staffordshire and part of the Darwin bicentenary celebrations. Maer was where Charles married his cousin Emma Wedgwood in this church.

February also saw the launch of the Cannock Chase Geotrail that I had worked on extensively in 2008. This is the Glacial Boulder (as opposed to a glacial boulder), turned into a monument.

In March I was part of a field course to Wenlock and Ludlow, classic British geological localities. This is Ludlow Castle from the Whitcliffe section…

… ran a one day field course to the Ercall Quarries in Shropshire, site of the Cambrian/Precambrian unconformity (when life became hard!)…

…I also went down the Ecton copper mine …

… and with the weather improving went for a walk in the Manifold Valley. This is the view from Thor’s Cave.

April saw two visits to Pembrokeshire – restore this! …

… Ogmore and Southerndown in South Wales (here is the Liassic / Lower Carboniferous unconformity) …

… and also had a brief holiday in Devon (this are feldspar megacrysts in the Dartmoor Granite).

With spring having sprung, May saw a visit to Ashridge, Hertfordshire to see the bluebells.

The second half of the year to follow…

OpenGeoscience

hypocentre — Tue, 01 Dec 2009 00:02:12 +0000

BGS Make-a-map

Well, it’s about time. The British Geological Survey has been lagging behind its US cousin for some time now. Like the USGS, the BGS is funded by the taxpayer but unlike the American version the data has always been hard to get hold of and expensive. Bits of data have become available slowly as the BGS has gone digital. The 1:625000 scale digital geology map was released through geoindex and the OneGeology global geological mapping portal and this year I’ve been making a lot of use of their on-line rock lexicon, but up until now the 1:50000 digital geology maps have only been available via a paywall to universities or in paper form for the great unwashed.

Today, the BGS released their OpenGeoscience portal, a free service for non-commercial private study, research and educational activities for viewing geological maps, downloading photographs and other information.

There are six OpenGeoscience sections. The Data section covers parts that we’ve had access to previously like the geoindex graphical front end to the BGS’s data holdings such as maps, boreholes, earthquakes and the like, the lexicon of terms used on BGS maps, their rock classification scheme and their database of mineral and rock samples. The education section also links to stuff we have had before – notably ‘Make-A-Map’ for creating basic geological maps of the British Isles. They also (somewhat bravely) provide a link to their new climate change poster which shows that climate change is nothing new and puts into context the current fluctuations with respect to those over geological time.

The maps section provides three ‘views’. The first, a ’simple’ view allows a zoomable view down to street level with the 1:50000 geological map (where available – not Northern Ireland yet) as an overlay. The geology layer, the transparency of which is variable with a slider control, is a vast improvement on what was previously available to the general public. However, the street map is several years out of date and the satellite view is quite poor resolution. Their ‘intermediate’ view is actually the 1:625000 geology kml layer for Google Earth that has been available through OneGeology for some time and which I blogged about previously here back in August last year. The ‘advanced’ data allows users to down load the 1:625000 data in in ESRI© and MapInfo© formats and also view the 1:50000 data using their Web Map Service.

As an educator, however, the best part for me is GeoScenic, the browsable collection of the BGS’s photographs. I can see this being really useful for examples in lectures.

Finally, and really something quite interesting, is a downloadable version of BGS·SIGMAmobile, the BGS ‘digital field data capture system’ (geological field notebook connected to a database) designed to run on a rugged tablet PC with integrated GPS units. Effectively this is a heavily customised versions of ArcMap 9.2 and MS Access 2003 and is something I’m going to be trying out in the near future.

All in all, it is good to have everything together in one portal, but much is not new and still lags behind what is accessible for the US.

Extreme Gardening

hypocentre — Sun, 15 Nov 2009 23:36:21 +0000

This weekend I’ve been involved in a bit of geoconservation work a.k.a. extreme gardening. Working with the Staffordshire RIGS group, we were cleaning up a couple of outcrops along the Hamps and Manifold Geotrail at a site called Ladyside Wood (Location 19 on the map below). The parent body of Staffordshire RIGS, UKRIGS (UK Regionally Important Geological / Geomorphological Sites) has just changed its name to GeoconservationUK. Personally I think that this is a poor choice as the RIGS groups do so much more than geoconservation. I would have preferred GeodiversityUK which would have given a feel for the range of things that we do.

But anyway, back to the Manifold Valley …

Part of the Hamps and Manifold Geotrail - Ladyside Wood #19

The map shows that the Ladyside Wood locality should display the transition from the reef knoll facies of the Milldale Limestone (purple), through the bedded facies of the Milldale (dark blue) to the overlying bedded Ecton Limestones (pale blue). Unfortunately the sections have become somewhat overgrown.

Milldale Limestone section before geoconservation

Ecton Limestone section before geoconservation

Often in geoconservation we find that there is a certain tension between the geoconservationists who want to expose the outcrops and the bioconservationists who want to preserve certain plants. Before starting clearance on this section we consulted with the National Trust who own the land. Can you spot what was the only plant they asked us to leave? OK, I admit it is difficult from the photos but the answer is the yellowish shrub on the right of the lower image. The bizarre thing is that is a flowering red currant – a garden shrub and not even native to Britain. Apparently it looks pretty when it flowers!

Anyway, after five hours of pruning, scraping, sawing and scrubbing, we managed to get the outcrops returned to some of their former glory.

Milldale Limestone section after geoconservation

Ecton Limestone section after geoconservation

This is the first of what I hope to be many geoconservation sessions to be run by Staffordshire RIGS.