LANDHEVNING

The Ranafjorden area in northern Norway is a region of increased seismicity and
anomalous land uplift. There is evidence for recent movements in the bedrock;
1) A total of 0.89 m uplift of a bladder wrack mark from 1894 to 1990 in
Hemnesberget; 2) Anomalous low uplift of the islands of Hugla and Tomma in the
outer Ranafjorden area (0,0 0.06 and 0.07 m from 1894 to 1990 compared to 0.25-
0.30 m in the area to the north and the south); 3) Associated with the 1819
magnitude 5.8-6.2 earthquake in the Ranafjorden area, an uplift of a shallow
sea floor above sea level during an aftershock was reported in the bay Ut-
skarpen. During the main earthquake a major land slide occurred at the same
location. This earthquake is the largest North European near-shore earthquake
recorded in historical time; 4) An uplift of approximately 1 metre of a farm-
house in the 1870's at Båsmoen. The observation has been made relative to the
two neighbouring mountains Snøfjellet and Høgtuva. 5) Approximately 0.5 m
uplift of a boathouse in the bay Straumbotn during the last 50 years.
There are, consequently, indications of recent faulting in the Ranafjorden area
It is, however, difficult to find conclusive evidence for postglacial and
present-day movements along specific faults. We have therefore established
a Global Positioning System (GPS) network designed to measure the active
geological strain in the area.

Dissertation Submitted in Partial Fulfillment of Requirements for the Degree of Doktor der montanischen Wissenschaften (Dr.mont.).

Dissertation Submittet in Partial Fulfilment of Requirements for the Degree of Doktor der Montanistischen Wissenschaften (Dr.mont.).

Neotectonic crustal deformations have been reported at a large number of locations in Norway (both on local and regional scales). The NEONOR Project represents a national effort by several national research and mapping institutions to investigate these phenomena through a multidiciplinary approach. Both the industry and the Norwegian Research Council contribute with major financial support. The main objectives of the NEONOR. Project are to systematically collect data, and to provide answers to the questions: 1) How can recent crustal deformation be characterised in time and space? 2) What processes cause the neotectonic crustal deformations? 3) What are the implications for migration and occurrence of fluids (especi- ally hydrocarbons and groundwater) in bedrock? 4) What are the implications for geohazard related to constructing sensitive installations like pipelines, gas-terminals and hydropower-plants. The initial phase of the project includes a systematic collection and charac- terisation of known deformations. New geological, geodetic and seismological data are, however, also acquired.

This report constitutes the itinerary for a two-day field excursion to postglacial faults and rock avalanches in northern Troms and western Finnmark. Day 1 has three stops along the route from Tromsø to Nordmannvikdalen in Kåfjord, Troms. Day 2 has two localities along the Stuoragurra fault in Masi. The Nordmannvikdalen and Stuoragurra faults are part of the Lapland province of postglacial faults which consists of nine reverse faults and two normal faults in northern Fennoscandia. The faulting was most likely associated with major earthquakes with magnitudes of 7-8 on Richters scale.
The reverse Stuoragurra fault has a length of 80 km and a scarp height of maximum 7 metres. The fault is located within the regional Mierujavri Sværholt Fault Zone which is of Proterozoic age. The fault cross-cuts glaciofluvial deposits and is consequently younger than 9600 C14 yars. During 1998, two trenches were made across the Stuoragurra Fault, between Kautokeino and Masi. For the first time, the fault was directly observed in the bedrock. The fault did not penetrate the overlying glacial materials, but rather folded them, forming a blind thrust. Large liquefaction and other deformation structures were found in the glaciofluvial sediments in both trenches. Veins of angular and subangular pebbles from the local bedrock (Masi Quartzite) penetrate more than 10 metres laterally from the thrust plane and into the sediments in the footwall. It is thought that these veins were possibly injected during the fault activity. Deformational structures seen in the trench can be explained as a result of one major fault event.
The normal Nordmannvikdalen fault has a length of 1.5-2 km and a scarp height of one metre. The fault is most likely due to a deep-seated deformation, but a gravitational origin can not be ruled out. Two rock avalanches in Nordnesfjellan and Manndalen in Lyngenfjorden, northern Troms are described. The avalanches in the area were most likely triggered by the large earthquakes which were formed during the postglacial faulting.

The NEONOR project represents a national effort by several national research
and mapping institutions to study neotectonic phenomena through a
multidisciplinary approach. Information on present land uplift, seismiticiy,
rock stress and postglacial faults is compiled in a 1:3 million map of Norway
and adjacent areas. There is a good evidence for conjugate set of normal
faults perpendicular to the extensive system of NE-SW trending reverse faults
in northern Fennoscandia. (Forkortet)

Geodynamic modelling of the present crustal uplift indicates that the uplift of western Norway and northern Norway is partly due to other mechanisms that the glacioisostatic rebound. We have also deduced a new model based on the 'seismic pumping' mechanism to explain the observed correlation between land uplift and groundwater yield in Norway. Rock avalanches and landslides represent the most hazardous effects of earthquakes in Norway with its mountainous terrain, deep fjords and relatively large areas with unstable quick-clay. New seismic mini-arrays in the Ranafjorden area and the northern North Sea have sharply defined zones of increased seismicity. A total of 350 earthquakes have been detected in the outer Ranafjord area during the project period (2 1/2 years) with magnitudes up to 2.8. This is very high onshore Baltic Shield areas. The return perios of magnitude 6 and 5 earthquakes have been estimated to 1500 and 130 years respectively. The M6 earthquake in 1819 in Mo i Rana triggered several rockfalls and a landslide.

The NEONOR project represents a national effort by several national research and mapping institutions to study neotectonic phenomena through a multi-diciplinary approach. Information on present land uplift, seismicity, rock stress and postglacial faults is compiled in a 1:3 million map of Norway and adjacent areas.

Den kavartærgeologiske kartleggingen av kartbladene Arendal 1611 IV og Tromøy 1611 I ble foretatt i 1994 og 1996 som en del av den systematiske kartleggingen i M 1:50 000 som ble gjort i NGUs regi i Vestfold og nedre Telemark. Beskrivelsen gir en kort oversikt over berggrunn, landformer, isbevegelser og landhevning/strandforskyvning før de enkelte løsmasser blir klassifisert og beskrevet. Mye av det småkuperte landskapet er dominert av bart fjell eller tynt, usammenhengende dekke av morenemateriale. De største og mest markerte løsavsetningene finnes i forbindelse med Raet i form av randmorener og breranddeltaer. Under marin grense er det stedvis avsatt mektige finkornige hav- og fjordavsetninger, særlig i forsenkninnger og tidligere fjordbassenger langs Ramorenen og i de store dalsenkningene som for eksempel Nidelvas dal. Til slutt i beskrivelsen gis det en kort vurdering av løsmassenes egnethet til forskjellige formål. De kavartærgeologiske kartene er digitalisert og plottekart følger vedlagt.

Den kvartærgeologiske kartleggingen av kartblad Vinjeøra ble foretatt i 1995 og 1996 som en del av den systematiske kartleggingen i M 1:50 000 som ble gjort av NGU. Beskrivelsen gir en kort omtale av geologiske hendelser i kvartærtiden og prinsippene for kvartærgeologsk kartlegging, blant annet med hensyn til løsmassinndeling, mektighet og lagfølge, kornstørrelse og overflateformer. Den gir en meget kort omtale av berggrunnsgeologi og landskapsformer. Deretter beskrives ulike avsetningstyper som forekommer innen kartbladet, både med hensyn til utbredelse, mektighet og karakteristiske egenskaper. Geologisk utvikling med hovedvekt på sluttfasen av isavsmeltningsforløp, strandforskyvning, elve- og bekkeerosjon og skred og andre massebevegelser. Til slutt omtales løsmassenes egnethet til ulik bruk. Det kvartærgeologiske kartet er digitalisert og plottekart er vedlagta