Sumatra-jordskælvet - de geofysiske konsekvenser

Sumatra-jordskælvet udløste en næsten ubegribelig menneskelig katastrofe i landene omkring Det Indiske Ocean med tæt på 300.000 omkomne. Langt de fleste blev ofre for den tsunami, som jordskælvet satte i gang. Jordskælvet er også opsigtsvækkende rent videnskabeligt på grund af sin voldsomhed og de naturvidenskabelige fænomener der fulgte med; den enorme brudzone, de store forskydninger, tsunamien og de kraftige rystelser, som satte hele jordkloden i svingninger

Comprehensive Nuclear-Test-Ban Treaty – a peace-keeping initiative with scientific impact

Any major shaking of the Earth can be recorded on a seismograph regardless of the nature of the source. Earthquakes and large explosions generate waves with similar frequency content. This fact has been used for decades to construct systems to monitor detonations of underground nuclear explosions. The quality of the monitoring system has increased significantly in recent years, and we demonstrate here that the data are useful in Danish earthquake research

Seismology: neotectonics and structure of the Baltic Shield

Recent Danish seismological projects involving neotectonic investigations and structural studies have determined the edge of the Baltic Shield underlying Denmark. The most active earthquake zones in Denmark are located in northwestern Jylland and adjoining offshore areas, and in the region around Kattegat, Øresund and north-east Sjælland (Fig. 1). This pattern was originally recognised by Lehmann (1956) and has been confirmed by several later studies, e.g. Gregersen et al. (1998). Recent, more detailed investigations have documented that changes in the pattern of earthquake activity have occurred within a short time span. The most pronounced example of change – possibly related to exploitation of hydrocarbons – is an activity recorded in the Central Graben area of the North Sea that was first documented by Gregersen et al. (1998). The south-western margin of the Precambrian Baltic Shield separates areas of different earthquake activity (Fig. 1; Gregersen et al. 1991). Although lithospheric stresses are more or less uniform in northern Europe, there are pronounced differences in the behaviour of the lithosphere across Denmark. The north-eastern area underlain by the Baltic Shield experiences brittle failure as recorded by common earthquakes, whereas earthquakes are virtually absent in the region southwest of the shield (Fig. 1). The margin of the Baltic Shield as defined by earthquake activity is not identical with that distinguished structurally in sedimentary studies (EUGENO-S Working Group 1988; Vejbæk & Britze 1994), in crustal studies (Abramovitz & Thybo 2000), or by recent studies of the structure of the subcrustal lithosphere (Gregersen et al. 2002; Shomali et al. 2002). The physical edge of the Baltic Shield cannot be uniquely determined on the basis of seismological studies. The earthquakes recorded, although of low magnitude, do give information about the released stresses. The earthquakes seem to be a response to a dominant NW–SE compression, also apparent elsewhere in Scandinavia and northern Europe (Slunga et al. 1984; Slunga 1989; Gregersen 1992; Müller et al. 1992). These stresses are part of the large-scale stress systems associated with continued plate motion pattern (Gregersen & Basham 1989; Zoback et al. 1989). In contrast to present low-magnitude earthquakes, postglacial sediments in northern Scandinavia have preserved features interpreted as caused by earthquakes of magnitudes around 7; these major, c. 9000 years old earthquakes are believed to be related to the post-glacial uplift of Scandinavia (e.g. Arvidsson et al. 1991; Gregersen 2002). Earthquakes are always related to fault activity, but attempts to link recent earthquakes occurring in and around Denmark to geologically known faults have only been partly successful (Gregersen et al. 1996). The most significant fault zone in Denmark, the Sorgenfrei–Tornquist Zone, is only locally active. Recent geodetic and seismic investigations demonstrate that the two sides of the Sorgenfrei–Tornquist Zone are characterised by different patterns of deformation, but the zone itself is not defined by a present-day seismicity trend crossing the central parts of Denmark (Fig. 1)

Goblet Cell Carcinoid in a Patient with Neurofibromatosis Type 1: A Rare Combination

Neuroendocrine tumors are rare tumors primarily located in the gastrointestinal tract. Goblet cell carcinoid is a rare subgroup of neuroendocrine tumors located in the appendix. Neurofibromatosis type 1 is an autosomal dominant disorder caused by a mutation in the NF1 gene. Patients with neurofibromatosis type 1 have an increased incidence of typical neuroendocrine tumors, but it is unknown if this is the case with goblet cell carcinoids. We describe a patient with both neurofibromatosis type 1 and goblet cell carcinoid, that according to literature would occur in 0.00017 per million per year. This may suggest a previously unknown association between neurofibromatosis type 1 and goblet cell carcinoids

Gastric transit and small intestinal transit time and motility assessed by a magnet tracking system

<p>Abstract</p> <p>Background</p> <p>Tracking an ingested magnet by the Magnet Tracking System MTS-1 (Motilis, Lausanne, Switzerland) is an easy and minimally-invasive method to assess gastrointestinal transit. The aim was to test the validity of MTS-1 for assessment of gastric transit time and small intestinal transit time, and to illustrate transit patterns detected by the system.</p> <p>Methods</p> <p>A small magnet was ingested and tracked by an external matrix of 16 magnetic field sensors (4 × 4) giving a position defined by 5 coordinates (position: <b>x, y, z, and angle: θ, ϕ)</b>. Eight healthy subjects were each investigated three times: (1) with a small magnet mounted on a capsule endoscope (PillCam); (2) with the magnet alone and the small intestine in the fasting state; and (3) with the magnet alone and the small intestine in the postprandial state.</p> <p>Results</p> <p>Experiment (1) showed good agreement and no systematic differences between MTS-1 and capsule endoscopy when assessing gastric transit (median difference 1 min; range: 0-6 min) and small intestinal transit time (median difference 0.5 min; range: 0-52 min). Comparing experiments (1) and (2) there were no systematic differences in gastric transit or small intestinal transit when using the magnet-PillCam unit and the much smaller magnetic pill. In experiments (2) and (3), short bursts of very fast movements lasting less than 5% of the time accounted for more than half the distance covered during the first two hours in the small intestine, irrespective of whether the small intestine was in the fasting or postprandial state. The mean contraction frequency in the small intestine was significantly lower in the fasting state than in the postprandial state (9.90 min^-1vs. 10.53 min^-1) (p = 0.03).</p> <p>Conclusion</p> <p>MTS-1 is reliable for determination of gastric transit and small intestinal transit time. It is possible to distinguish between the mean contraction frequency of small intestine in the fasting state and in the postprandial state.</p

Earthquake in Southern Sweden wakes up Denmark on 16 December 2008

A moderately strong earthquake struck southern Sweden 5 km south-west of the town of Sjöbo, 60 km east of Malmö, in the early morning at 6:20 a.m. local time on 16 December 2008. The epicentre was located in Skåne, a region that is known for its extremely low seismicity, and its location was determined to be 55.5°N and 13.6°E with an uncertainty of about 6 km. A depth of 9 km with an uncertainty of 3 km was obtained from teleseismic observations at the Yellowknife seismic array, USA. Since waveform data from the Swedish national seismic network are not yet available, depth estimation using local stations has so far not been attempted. During the period 1970–2008, only three small earthquakes were detected in the region; the largest measured 2.8 on the local Richter scale. To our knowledge none of these previous earthquakes were felt by people. The historical archives dating back to 1375 show that 14 other earthquakes have been felt in the area. The largest of these, recorded in 1894, was felt over an area of 7300 km2 and had an epicentre 50 km east of the 16 December 2008 earthquake (Scandinavian Earthquake Archive 2003). The activity in southern Sweden is similar to that of northern Sjælland and north-western Jylland, and confirms the low seismicity of the region (Gregersen et al. 1991)

Kan jordskælv forudsiges? - brugbare forudsigelser er langt væk

Det er en klassiker. Et stort jordsk&aelig;lv&nbsp;sender huse i grus, mange&nbsp;mennesker mister livet, og endnu&nbsp;flere bliver hjeml&oslash;se. Katastrofen&nbsp;er omfattende og tragedien ub&aelig;rlig.&nbsp;Frem af kaos dukker en person, som&nbsp;h&aelig;vder at have forudsagt jordsk&aelig;lvet,&nbsp;og hvis advarsler er blevet ignoreret&nbsp;af myndigheder og borgere.&nbsp;Hvis bare vi havde lyttet, kunne&nbsp;menneskeliv v&aelig;re sparet

Jordskælv i Skåne - kraftige rystelser i Danmark

En helt almindelig s&oslash;vnig vintermorgen,&nbsp;d.16. december 2008, blev&nbsp;tusindvis af danskere v&aelig;kket ca.&nbsp;kl. 6.20 af de uvante rystelser fra&nbsp;et jordsk&aelig;lv. Huse knagede, ting&nbsp;og sager raslede, senge svajede og&nbsp;uhyggelige lyde h&oslash;rtes fra undergrunden.&nbsp;Nogle steder var oplevelsen&nbsp;s&aring; intens, at forskr&aelig;kkede mennesker&nbsp;l&oslash;b udenfor &ndash; ganske som&nbsp;man b&oslash;r, hvis man pludselig befinder&nbsp;sig midt i et kraftigt jordsk&aelig;lv

Seismic activity in Denmark: detection level and recent felt earthquakes

The Geological Survey of Denmark and Greenland (GEUS) records seismological data at six locations in Denmark (Fig. 1) and all data from these stations are manually reviewed for events like earthquakes and explosions. The identified events are analysed and located, in many cases using supporting data from stations outside Denmark. Seismic events have been recorded instrumentally in Denmark since 1929, but earthquakes felt in Denmark have been reported as far back as 1515 (Lehmann 1956; Gregersen et al. 1998; GEUS 2012). This article reports on the developments in detection level of both man-made events and natural earthquakes within the Danish Exclusive Economic Zone (EEZ) from 2000 to 2012. Changes in detection level are mainly due to the availability of data from new seismic stations in Sweden and Norway as well as from a GEUS test station at Gøttrup in NW Jylland. As a case study, the list of events on and around Bornholm is reviewed. Also described here are the reported intensities at two recent felt events in Denmark (North Sea magnitude 4.3 on 19 February 2010 and Kattegat magnitude 4.1 on 6 August 2012)