Now that the new dates for the 8th PATA Days 2017 in New Zealand are fixed, it is time to bring to your attention an exceptional paper that was already published in 2016. I planned to write a review long time ago, but I just managed to do so now. The paper by Quigley et al. is not only likely to become your favourite read during the long flight to New Zealand, but it will also serve as an extremely valuable contribution to the study of earthquake environmental effects (EEEs) in general. The authors report on, and summarise, the effects that the 2010-2011 Canterbury earthquake sequence had on the environment. The paper is special in many ways: more
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3He dating of rockfalls helps to distinguish between proximal and distal paleo-earthquakes in Christchurch, NZ2014-10-13 | in Earthquake
The 2011 Christchurch earthquake series had severe consequences and surprised scientists for many reasons. Ground motions were extremely strong despite the relative moderate magnitudes of the quakes (MW 5.3-7.1). The events happened on a system of hitherto unknown faults, some of which are located directly below Christchurch. Earthquake environmental effects (EEE), especially liquefaction, were intense and widespread. It turned out that subsequent quakes reactivated the same feeder dikes of sand blows, showing that saturated sediments are susceptible of liquefaction no matter if they had been liquefied recently (also see the paper of Quigley et al. (2013) on the liquefaction effects). Another stunning lesson was the occurrence of intense rockfall in the vicinity of Christchurch. In a recently published study, Mackey and Quigley (2014) dated rockfall boulders with 3He and show that they allow to estimate the recurrence intervall of local seismic events like the 2011 series. This works is a very interesting way to use EEE for paleo-earthquake studies. more
2013-02-25 | in Earthquake | one response
Today’s post of the Landslide Blog about a rockfall caused by a volcanic earthquake reminds me about something that’s in my mind for years already. Could we use dust deposits as a paleoseismological archive? Dust clouds of all sizes, ranging from tiny to huge, can be associated with seismic shaking, especially in arid and mountainous regions. Here I have collected a few videos I found on YouTube. When large amounts of dust settle they should form a distinctive layer recognizable in the sedimentary record, comparable to volcanic ash deposits. Of course they will be harder to be identified, since the material is the local one. I guess this could be done, similar to turbidites in marine paleoseismology. There are papers that describe changes in the aerosol content in the atmosphere after earthquakes, so why not look for them on earth? more
Recently, scientists from Switzerland came up with the news that fractured bedrock might amplify earthquake shaking. The say they observed an increase by factor 10, which seems huge. I knew amplifying by sediment basins, but this is new to me.
100 years ago on 6 January, Alfred Wegener presented his continental drift theory for the first time. The Blogosphere was full with articles, among them: more
2011-07-01 | in The Friday Links
Some good articles came up last week, and two interesting things happened in northwestern Europe. A small earthquake (M2.7-M3.4) hit northern Netherlands in the Groningen area and people claimed light house damages despite the low magnitude. The event was caused by natural gas production. The gas company, Nederlandse Aardolie Maatschappij (NAM), even has an online-formular for that! more
2011-06-13 | in Uncategorized
On Monday, 13 June, Christchurch was again rocked by earthquakes that caused damages and left people injured. Three significant events happened within two hours. At 1:00 UTC a mb5.0 event occured, followed by a Mw6.0 at 2:20 UTC and a M4.6 at 2:40 UTC. The strongest event caused instrumental intensities of up to VII close to the city. Update: Geonet reports a magnitude of 6.3. more
2011-02-23 | in Teaching | 3 responses
A M6.3 earthquake hit Christchurch, New Zealand on 22 February (21 Feb in UTC), leaving at least 75 people dead and hundreds injured or missing. Hundreds of houses were destroyed, including the Christchurch Cathedral, and damages will probably sum up to some billion dollars. On 4 September 2010 (3 Sept in UTC), a M7.0 event struck Christchurch, but then no one was killed. So: what’s the difference between the two events?