An M>6 earthquake ~750 BC in SE Sweden

Abstract

At about 780-750 BC, a major earthquake struck southeast Sweden. At Branteträsk, the bedrock of quartzite was heavily fractured into big, flat blocks. Local people turned the site into a quarry for flat blocks to be placed around the Late Bronze Age graves at Brantevik, the big flat blocks of the sarcophagus, and two 5 tons monoliths transported 30 km to the SSW and erected as the bow and stern stones in the huge ship monument of Ales Stones. Rock carvings from the Bronze Age at Jär-restad became traversed by numerous fractures. Similar rock carving fracturing was observed at six other sites within a radius of 5 km from Branteträsk. In the shore cliff at Ales Stones a seismite was recorded and dated at 780-750 BC. At Glimme hallar, 4 km WSW of Brantevik, the bedrock shows signs of young tectonization. At Lillehem, 40 km to the NNW of Branteträsk, seismically disturbed beds were recorded and dated at the Late Holocene. The seismic event is concluded to have occurred around 780-750 cal.yrs BC and to have had a magnitude in the order of 6.3 to 6.8 and an intensity of about IX on the IES scale.

Full text

Open Journal of Earthquake Research, 2014, 3, 66-81
Published Online May 2014 in SciRes. http://www.scirp.org/journal/ojer
http://dx.doi.org/10.4236/ojer.2014.32008
How to cite this paper: Mörner, N.-A. (2014) An M > 6 Earthquake ~750 BC in SE Sweden. Open Journal of Earthquake Re-
search, 3, 66-81. http://dx.doi.org/10.4236/ojer.2014.32008
An M > 6 Earthquake ~750 BC in SE Sweden
Nils-Axel Mörner
Paleogeophysics & Geodynamics, Stockholm, Sweden
Email: morner@pog.nu
Received 22 March 2014; revised 28 April 2014; accepted 6 May 2014
Copyright © 2014 by author and Scientific Research Publishing Inc.
This work is licensed under the Creative Commons Attribution International License (CC BY).
http://creativecommons.org/licenses/by/4.0/
Abstract
At about 780-750 BC, a major earthquake struck southeast Sweden. At Branteträsk, the bedrock of
quartzite was heavily fractured into big, flat blocks. Local people turned the site into a quarry for
flat blocks to be placed around the Late Bronze Age graves at Brantevik, the big flat blocks of the
sarcophagus, and two 5 tons monoliths transported 30 km to the SSW and erected as the bow and
stern stones in the huge ship monument of Ales Stones. Rock carvings from the Bronze Age at Jär-
restad became traversed by numerous fractures. Similar rock carving fracturing was observed at
six other sites within a radius of 5 km from Branteträsk. In the shore cliff at Ales Stones a seismite
was recorded and dated at 780-750 BC. At Glimme hallar, 4 km WSW of Brantevik, the bedrock
shows signs of young tectonization. At Lillehem, 40 km to the NNW of Branteträsk, seismically
disturbed beds were recorded and dated at the Late Holocene. The seismic event is concluded to
have occurred around 780-750 cal.yrs BC and to have had a magnitude in the order of 6.3 to 6.8
and an intensity of about IX on the IES scale.
Keywords
Earthquake, Late Bronze Age, 750 BC, Sweden, Ales Stones, Rock Carvings
1. Introduction
During the time of deglaciation, when the glacial isostatic uplift peaked at rates in the order of tens of cm per
year, Sweden was a high-seismic region [1]-[3]. Even in the Late Holocene, there are several high-magnitude
events recorded [3]-[5]. The latest high-magnitude event recorded is an event occurring around 900 BP [2] [4]. It
faulted the Viking shoreline in SW Sweden and probably set up a tsunami wave that destroyed two Viking ships
in the ancient harbour of Galtabäck. A C14-date of the ship gave 1172 ± 73 cal.yrs AD [6], which is quite close
to a major historical event at 1174 as recorded in the chronicles [7].
Therefore, it may not be so strange that we are now able to present evidence of a major earthquake in SE
Sweden [8], which can be tied into the Late Bronze Age cultural history of the area [9] [10].

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Furthermore, there was a quite strong earthquake on December 16, 2008, in SE Sweden with a magnitude of
4.3, felt over an area of a radius of at least 200 km and with occasional fracturing of churches and other build-
ings in the vicinity of about 30 km.
2. Investigation Area
The present seismotectonic study refers to SE Sweden, an area often named “Österlän”. Figure 1 gives the geo-
graphic setting of the main sites discussed, and where the focus is on Brantevik where the prime evidence of an
earthquake was first discovered [8].
The geological setting will be discussed below in connection with the tectonics studies. The old fault patter is
dominated by NW-SE and SW-NE trending faults.
3. Holocene Sea Level Changes
The sea level changes in the Brantevik area are presented in Figure 2 (cf. my precious curves for the Kivik-Vi-
temölle area and the Kåseberga area in [11]). Holocene sea level peaked at +2.2 m 4600 cal.yrs BC and at +2.1
m at 1000-800 cal.yrs BC [12]. The last level constitutes an important marker level along the coasts and pro-
vides a reference level for the sea level in the Late Bronze Age of Österlän [9].
4. Description
The main area is in the Brantevik-Järrstad-Simrishamn area with additional sites at Kåseberga 30 km to the SSW
and at Lillehem 40 km to the NNW (Figure 1). The paleoseismic event has been discussed in a preliminary re-
port [8], like its relation to the Late Bronze Age archaeological development of the region [9] [10]. Additional
fieldwork was undertaken in 2013 and 2014.
4.1. Branteträsk
Branteträsk is the key site [8] [9]. It was found in 2012. The site consists of a swampy depression and surround-
ing flat ground, which on the western side was found to consist of a bedrock of quartzite, strongly fractured in to
big blocks (Figure 3). Furthermore, one block had been laid up in inclined position and this was obviously a
human act. The swamp was cored at 21 points. In general, the bedrock surface of the basin is covered by half a
metre of alder peat, suggesting that the swamp filling is of Late Holocene age. The idea that we might be dealing
with an ancient quarry emerged [9].
The fractured quartzite bedrock surface was cleaned over a large area. The quartzite surface is ice scoured and
strongly weathered from postglacial exposure. The fracture surfaces on the other hand are fresh and have very
Figure 1. Geographical location of the main sites discussed.

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Figure 2. Sea level changes at Brantevik during the last
5000 years [12].
Figure 3. Branteträsk is a swampy, partly water filled, de-
pression. To the northwest it is bounded by a heavily frac-
tured bedrock of quartzite, partly broken up in big blocks by
multi-directional extensional forces indicative of seismic de-
formation. Later, the blocks and the depression were utilized
as quarry of monoliths for Ales Stones and flat blocks for
the Late Bronze Ages graves at Brantevik. Yellow dot marks
place of block laid up in inclined position. Red line and dots
mark main coring section and sites.
sharp fracture edges. Figure 4 gives a typical picture of the sharp, open fractures. Obviously, we are dealing
with a 3 dimensional extensional opening. This can only have been produced by a major earthquake.
A tot al of 70 fractures were measu red: 33 in 355 ± 14, 19 in 283 ± 13, 12 in 57 ± 15, 4 in 324 ± 12 and
2 in 21 ± 3, which is quite different directions as those of the main old tectonic pattern.
The lithology of the quartzite is almost identical to that of the bow and stern stones in the Ales Stones mega-
lithic monument some 30 km to the SW, suggesting that they were indeed collected in the Branteträsk quarry
about 750 BC and transported by raft to the shore below the place of erection of the monument [9].
At Brantevik, there previously was a huge grave from the Bronze Age known as “Brantarör” [13]. It is now
gone, but we have a detailed drawing of it from 1777 showing a grave surrounded by, at least, 60 flat blocks and
with a central sarcophagus of 14 large and flat block. All those blocks must consist of layered quartzite quarried
in the vicinity, i.e. in Branteträsk. The grave contained some bronze tools and an urn, which by E. Jonson [13]
was assigned an age of 800-500 BC. This fits perfectly well with an age of quarrying at Branteträsk of 800-700
BC [8]-[10].
Only one core (7 in Figure 3) penetrated sediments going all the way back to the time of deglaciation (Figure
5). In this core there was a thin layer of angular pieces of fractured quartzite, which is likely to represent spall
from a stone “industry” in the Bronze Age or Neolithic. The intension is to obtain a new core and sample the
sediments just above and below the “spall horizon” for radiocarbon dating.

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Figure 4. The fractured bedrock of Cambrian quartzite. The fracture surfaces are fresh and the fracture
edges are knife-sharp. The bedrock surface, on the other hand, is strongly weathered with marks from
glacial scouring. The main deformational force is extensional, indicating a seismic origin. A secondary
deformation is recorded in the removal of blocks (top image) and lying-up of a big block in inclined po-
sition (in the back-ground of the top image), which can only have been achieved by man, transforming
the site into a quarry.

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Figure 5. Core 7 penetrating the entire postglacial period
after the deglaciation some 15,000 years ago and exhibiting
a “spall horizon” of sharp quartzite fragments interpreted as
a record of the quarrying in Late Bronze Age time. In all the
other 20 cores, the quartzite surface is hit at a depth of about
0.5 m (equaling the depth of quarrying).
4.2. The Rocky Shores at Brantevik
The present coast around Brantevik is rocky consisting of lower Cambrian quartzite, known as “Hardeberga
sandstone”. The bedrock is traversed by major open fractures in 72 - 76 and secondary fractures in 28 succes-
sively moving over into 326.
At the resting place just off the site of rock carving “Simris 19”, 2 km north of Brantevik, the fractures can be
observed at a level not reached by the waves today, but well reached by the waves at the +2.1 m high-stand at
about 1000-800 BC (Figure 2). The fractures are well washed and abraded by sea waves (Figure 6), in total
contrast to the fractures at Branteträsk. This indicates that the fractures were formed at the latest part of the sea
level high-stand, i.e. some 800-750 BC (and clearly before the rapid regression 700-650 BC).
This was also observed just south of Brantevik: the fractures are affected by the abrasion of sea waves up to
the level of the waves of the high-stand at +2.1 m (Figure 2). Consequently, the fractures must be older than or
time equivalent to this high-stand. This is in full agreement with an age of the earthquake in the order of 800-
750 BC.
4.3. Järrestad Rock Carving
Just north of Järrestad, a flat quartzite bedrock surfaces is exposed. It is covered by over 100 rock-carvings from
the Bronze Age [9] [14] [15]. Already in 2003, I had noted that several pictures were traversed by fractures sug-
gesting a post-carving paleoseismic fracturing [2]. Resumed investigations indicated that there must have been a
seismic event of rock fracturing post-dating the carving [8]-[10].
This post-rock-carving fracturing was documented at 6 additional sites of rock-carvings (petroglyphs) from
the Bronze Age in the Simrishamn-Brantevik-Järrestad region (Figure 7), spanning an area of about 5 × 5 km
[8].
The surface of the quartzite bedrock is very smoothly polished by the glacial flow, and it contains excellent
glacial striae and crescent-marks indicative of a main ice flow from the NE (measured value: 51 ± 3). The sur-
face is traversed by a few large and open fractures in 34 and 316, and numerous minor fractures; viz. 63 in
290 ± 4 ± 8 (Figure 8).
Both glacial striae and crescent-marks are often cut by fractures indicating at least one phase of postglacial
fracturing ([2] p. 267). Resumed investigations of the rock-carvings [15] indicated that several of the petro-
glyphs must have been affected by a late phase of post-rock-carving fracturing [8]. This is illustrated in Figure 9,
Figure 10.
Consequently, there are good observational reasons documented in Järrestad and six additional sites for an

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Figure 6. The abraded fractures just above the +2.1 m sea level high-
stand at 1000-800 BC (Figure 2) exposed at the resting place opposite
the rock carving site “Simris 19” (compare with the very sharp-edged
fractures in Figure 4).
Figure 7. Fractured rock-carvings (yellow dots) and sites of bedrock
fracturing analyses (blue dots [8]-[10]).
episode of general bedrock fracturing within an area of 5 × 5 km (Figure 7) occurring in the Late Bronze Age
[8]-[10]. This, by itself, is indicative of an earthquake of an intensity of VIII [16].
4.4. The Glimminge Hallar Area
Glimminge hallar area constitutes the eastern part of a local granite horst (Figure 11).
The northwestern side of the granite horst is full of structures indicating deformations in postglacial time. Two
examples are given in Figure 12: open fractures of extension in the SW-NE direction with blocks tumbled down
on the present land surface.

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Figure 8. The smoothly glacial polished quartzite surface of the Järrestad rock-
carvings, traversed by a few open fractures in 34 (central horizontal) and 316
(slightly winding from left top to bottom), and numerous parallel minor fractures
in 290, traversed by a nearly perpendicular system in 15, which often cut across
the pictures.
Figure 9. Postglacial fracturing of crescent-marks at site Simris 19 (A) and a
post-carving fracturing of a foot picture from the Bronze Age at Järrestad (B).
Figure 10. Post-carving fracturing of petroglyphs at Järrestad [8] [11] [15]. (A) a
pair of “shoes” cut by post-carving fractures. (B) the “sun-ship” severely fractures
by post-carving fractures.

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Figure 11. The area is a fault-bounded local granite horst of irregular (somewhat
unclear) shape. Postglacially deformed bedrock occurs at sites 1 and 2. Site 3 is a
small quarry of strongly fractured bedrock. Site 4 is a rock-carving traversed by
minor fracture. Site 5 refers to a monolith (“Trollastenen”) of quartzite most
probably originating from Branteträsk.
Figure 12. Fractured bedrock at site 1 due to a main extensional force in SW-NE
direction. The picture to the right also indicates an anti-gravitational upward dis-
placement. The deformation is clearly of postglacial age. Blocks tumbled out to
the NW (right hand image) rest on the present land surface suggesting that the dis-
placement might be of Late Holocene age.
Signs of postglacial deformation are present also on the eastern side of the horst. At site 2, there is a heavily
fractured scarp (Figure 13, left) from where blocks have moved eastwards at a low angle in a loose hig-
gledy-piggledy way suggesting a young age of deformation. Just outside there is a lake (Figure 13, right) where
sediment coring was performed. Three cores were pushed down. All stopped at about 90 cm due to hard ground
(probably bedrock). Beneath a 60 cm layer of coarse silt/fine sand, there is 30 cm of peat, the uppermost and
lowermost 1 cm of which is under radiocarbon dating.
With the addition of the Glimminge hallar sites, the size and mode of bedrock deformation (Figure 7) may
now be estimated at an earthquake of intensity IX [16].
4.5. The Kåseberga Shore Sections
Figure 15 gives the setting of the 67 m long stone ship monument of Ales Stones [17] and the 4 sites here dis-
cussed (1 - 4) with the sections at the shore (1) in focus [9] [10] [17].
The shore section was found in 2009 and described in [11]. In 2011, it was subjected to an excavation,
GPR-studies, coring and radiocarbon dating [9] [18]. With the finding of the earthquake at Branteträsk [8] there
were new reasons to revisit the site.
Right above the beach cobble of a sea level high-stand dated at around 1000-800 BC, there is a black layer of
humus and charcoal, which was C14-dated at 785 ± 20 cal.yrs BC [12]. The organic layer is covered by sand,
assumed to represent the eolian sand drift from around 500 BC, and later slid material.

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Figure 13. Site 2 (the Glimmingehallar proper) with a strongly deformed bedrock hill of granite (left)
and a lake outside (right). Yellow arrows give the view direction of the photographs; 1: Figure 13, left, 2:
Figure 14, left and 3: Figure 14, right. Obviously the entire hill was strongly shattered and deformed
with blocks sliding off in eastward and northward directions. A Late Holocene age of deformation is in-
dicated. The final answer will come from the two C14-dates under measurement.
Figure 14. Left: the scarp seen from the north with a major open fracture (view 2). Right: the sliding-off
of blocks on the northern side (as seen from view 3). The blocks are very sharp-edged and rest loosely on
the present ground surface suggesting a Late Holocene age of deformation.
Figure 15. The Kåseberga area with the Ales Stone monument from the Late
Bronze Age and four sites analyzed [9] [18]. 1: the main shore section, 2: liq-
uefied and tectonized sediments, 3: excavation pit D with the cast of one of the
stones in the monument, and 4: excavation pit F with some liquefaction-like
structures.

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At the 2011 excavation [18] it was observed that there at the base of the sand unit occurred some well-washed
boulders, suggesting a possible sea level inundation. The study was followed up by six C14-datings [9]. A new
date of the organic layer gave 775 ± 35 cal.yrs BC (i.e. almost identical to the previous date). Charcoal from a
hearth in the sand layer was dated at 385 ± 35 BC (layer 5 in Figure 16).
After additional work in the section in 2013, it is now possible to identify the layer right above the organic
bed as a layer of liquefied, tectonized and down-slid material; i.e. it is classified as a “seismite” (Figure 16).
The stratigraphy of Figure 16 includes the following layers cf. [9].
7: base of a Viking Age midden [18] dated at 950 ± 50 AD.
6: eolian sand 2 with a strong humus soil of the Late Iron Age.
5: hearth with charcoal dated 385 ± 35 cal.yrs BC.
4: eolian sand 1 representing the general sand drift phase at 500-600 BC.
3: tectonized layer (i.e. a seismite) including down-slid boulders and a reworked bone dated at 1195 ± 85
cal.yrs BC (cf. Figure 18).
2: organic layer rich in charcoal dated 785 ± 20 and 775 ± 35 cal.yrs BC, further inland this land horizon is
dated at 1285 ± 65 cal.yrs BC (Figure 18).
1: beach shingle representing the high-stand 1000-800 BC (cf. Figure 2).
Figure 18 provides a condensed section perpendicular to the shore. The layer 3 seismite is marked in brown.
It consists of a liquefied basal bed with boulders in its upper part (Figure 17) that must have slid down from the
nearby scarp. It also includes reworked material (Figure 18).
Close to the west (site 2 in Figure 15), there is a section of about 18 m of late glacial deposits. In the upper
part, the sand and silt is tectonized, micro-faulted and liquefied (Figure 19). Earlier, it was assumed that this
deformation was of late glacial age. Now, it seems reasonable to connect it with the earthquake deformation and
seismites in the close-by shore section (30 m apart).
4.6. The Lillehem Sediment Deformations
In a road junction at Lillehem, there is a minor gravel pit. After cleaning, an interesting stratigraphy was exposed
including an old ice wedge cast filled with organic material, humus and at the base a bed of precipitated carbon-
ate (Figure 20 top). Laterally, the stratigraphy recorded tectonization and liquefaction (Figure 20 bottom).
Figure 16. Stratigraphy in the shore section at Kåseberga. Layer 3 (in-
cluding the boulders) represents a tectonized horizon of liquefied ma-
terial (flamed organic structures) and down-slid boulders (Figure 17).
The event should have taken place shortly after the dates obtained from
layer 2 (i.e. 775 ± 35 and 785 ± 20 cal.yrs. BC), and is here proposed
to be a correlative to the earthquake fracturing recorded at Branteträsk.
The erection of the Ales Stones monument is likely to have occurred
shortly after; i.e. at around 750 BC.

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Figure 17. The black land surface (layer 2 in Figure 16) is covered by
an irregular, partly liquefied, layer of humic sand (layer 3), in which
the blocks rest. This layer contains reworked material (Figure 18) and
constitutes a seismite of shaken and slid material.
Figure 18. Shore section cf. [18] with C14-dates in cal.yrs BC (red).
The brown layer is a seismite of deformed (liquefied) sediments and
slide material including reworked objects of mixed ages (bone 1195,
land snail 2324 and a shell fragment 9638 BC).
The development of a strong humus soil in the ice wedge cast and the precipitation below of carbonate need a
lot of time. This is consistent with the age obtained of the horizontal carbonate layer C14-dated at 4503 ± 43
cal.yrs BC.
The left side of the section is heavily tectonized with progressive down faulting (lower image). The tectonized
beds include fragments of the carbonate bed dated at 4503 BC. Consequently, the tectonization must post-date
this age.
The general down faulting in the order of 0.5 m is indicative of a significant liquefaction in the subsurface. All
this suggests the effects from a major earthquake in Late Holocene time. It seems reasonable that this earthquake
event is the same as the one identified in Branteträsk and Kåseberga.
5. Discussion
Multiple indications of a Late Holocene earthquake event have been presented above, and will now be consid-
ered together as to location, magnitude and age. In the first preliminary report, a magnitude of “M > 6” and an

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Figure 19. Liquefied (above) and micro-faulted (below) deposits in the upper
part of site 2 that may lead its origin from the same earthquake as that of the
seismites in the shore section.
age “around 1000 BC” or “in the period 1000-800 BC” were proposed [8] [9].
5.1. Fracture Pattern
The Glimminga hallar site (Section 2.4) documents extensional fracturing to the NE and the E, i.e. in directions
off the granite horst.
The bedrock fracturing at Branteträsk follows a clear 3-dimentional extension. The main direction is perpen-
dicular to the main fracture direction 355 - 175. This implies that the long axis of the strain ellipsoid must be in
265 - 85. The short axis should be perpendicular to this. The vector of the two additional fracture directions is
350 - 170, which is only 5 off the perpendicular direction of the long axis. If the long axis is extended west-
wards, it passes the granite horst (Figure 21).
At Järrestad, 63 fractures were measured in 290 and 19 in 14. It is this fracture system, which has fractured
the petroglyphs (Figure 9, Figure 10). The corresponding strain ellipsoid would have had its long axis in 20 -
200 and its short axis in 110 - 290 (with a recorded value 104 - 284). If the long axis is extended southwards,
is passes right west of the granite horst (Figure 21). The surface is also traversed by a few large and open frac-
tures (Figure 8). The vector of these two directions is 356 - 176, which is not too far off the long axis of the
strain ellipsoid. A southward extension of 176 passes just east of the granite horst.
The combined record (Figure 21) suggests that the granite horst might be the common point of ground mo-
tions; i.e. the epicenter of the earthquake and the point of primary faulting.
The tectonic map of the area [19] records the old, primarily Paleozoic and Mesozoic fault pattern. The granite
horst sticks our as a special structure; a separate granite block within an elongated NW-SE fault block (Figure
21). Figure 22 gives a SW-NE profile across the granite horst.
5.2. Estimates of Intensity and Magnitude
The estimate of intensity and magnitude depends on the character of deformational structures and the spatial
distribution of observations e.g. [16].
Bedrock fractures in the order of centimeters to a decimeter suggest an intensity of about IX (on the IES scale;
[16]). The liquefaction structures at Lillehem may suggest an intensity of VII-VIII (maybe even IX).

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Figure 20. Stratigraphy at Lillehem. There are minor structures of lique-
faction in the main section. The left side is heavily tectonized (lower image)
with down-faulting indicating the loss of some 0.5 m of space below,
which can only be achieved by liquefaction and venting of liquefied sand.
This event must post-date the 4503 ± 43 cal.yrs BC.
The accumulated extension of the 33 fractures at Branteträsk is 123 cm in 265 - 85 direction, and the open-
ing along the two other directions is 48 and 47 cm. This seems rather to suggest an intensity of about X (or at
least IX-X). At Järrestad 63 fractures were measures. Their width ranges form millimeters up to a centimeter at
the most. This gives a total accumulated extension in the order of a decimeter. The spatial distribution (5 km
from Järrestad and 4 km from Branteträsk to the granite horst) suggests an intensity of VIII-IX.
The spatial distribution of liquefactions provides a better mean of estimating intensity and magnitude. Lille-
hem lies 32 km north of the granite horst at Glimminge, and Kåseberga lies 20 km south of it. Applying the
magnitude/spatial distance distribution relation (e.g. [2], p. 39, Fig. 5), 32 km corresponds to M 6.3 - 6.8 and 20
km to M 6.0 - 6.4. Therefore, it seems likely that the magnitude of this earthquake had a magnitude in the order
of 6.3 - 6.8 judging from the sites available.
5.3. Age of Event
The fracturing of the petroglyphs at Järrestad and six additional sites (Figure 7) indicated that the earthquake

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Figure 21. The site 4 bedrock deformations indicate extension from the centre of the granite horst (light
brown). The long axes of the strain ellipsoids at Branteträsk (1) and Järrestad (3) are also directed to-
wards the granite horst. This suggests that the earthquake may have been located to vertical movements
of this horst.
Figure 22. Cross-section over the granite horst with the positions of the Glimmingehallar site (4), Jär-
restad (3) and Branteträsk (1). It seems likely that the earthquake recorded might have had its epicenter
located to vertical movements of the old horst block of granite.
must be younger than the Mid Bronze Age; i.e. younger than 1000 BC. The peat cover of the fractured (and
quarried) quartzite bedrock at Branteträsk indicates quite some time back in the Late Holocene. The Brantarör
grave seems to incorporate numerous blocks quarried at Branteträsk. Because the grave included bronze tools
and an urn dated at 800-500 BC, the quarrying post-dating the earthquake fracturing is likely to have occurred in
the Late Bronze Age at around 700 BC. Finally, if the quartzite megaliths were shipped out by boat or raft from
Brantevik to Kåseberga, the natural harbor only existed at the sea level high stand 1000-800 BC up to about 750
BC (Figure 2; [12]). The Brantarör grave had a location in direct association with the natural harbor [12] im-
plying that it is likely to have been built before 700 BC and maybe around 750 BC.
At Kåseberga, charcoals just below the tectonized horizon are dated at 780 BC. Taking into consideration that

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the wood burned into charcoal must have some age, we may set the actual burning at abound 800 BC. The sub-
sequent earthquake must have happened shortly after or at about 780-750 BC.
The earthquake deformation at Lillehem is dated as younger than 4500 BC. An age of 750 BC seems quite
reasonable from the stratigraphic evolution. Besides, we have no reasons to infer a second seismic event for this
deformation.
In conclusion, the age equation seems to provide a quite sharp age determination at around 780-750 BC.
5.4. Late Holocene Paleoseismicity
At the time of deglaciation, Sweden was a high-seismic area as a function of the very high rates of isostatic up-
lift [1]-[3] [5]. Even during the last 5000 years, when the isostatic uplift was not significantly higher than today,
earthquakes much stronger than those of today were recorded [2] [4] [5].
The Late Holocene records from NW Skåne may be of particular interest in comparison with the present re-
cord. A number of events of magnitudes well above M6 and maybe even reaching M7 were reported [2] [4] [20].
The strength of the documentation is that multiple criteria are applied for a congruent picture. So for example
shoreline faulting, rock fracturing, rock avalanches, liquefaction and earth slides were shown to have occurred
simultaneously at about 4800 C14-yrs BP. The youngest event recorded occurred at about 900 BP, maybe in
1174 (see above, section 1), with the documentation of a 1.1 m shoreline faulting, rock avalanches and possibly
also a tsunami dated AD 1172 ± 73 yrs.
Because the instrumental seismic records do not exceed M 4.3 (for example the Dec. 16, 2008 event with
epicenter 60 km west of the horst area here discussed), the seismological community has great difficulties in ac-
cepting any earthquake in the Late Holocene reaching M6 or above e.g. [21]. Coincidence in time between dif-
ferent events occurring at different sites or outcrops in nature is, for a geologist, a strong indication of a mutual
driving force, whilst it, for a seismologist, might be just a matter of statistical coincidence. It is quite interesting
that Gregersen and Voss [21] concluded: “one is left with a choice in the evaluation between coincidences or
common cause: earthquake. The field trip convinced the participating seismologists that the claimed signs of
earthquakes must be seriously taken into account”.
6. Conclusions
The present paleoseismic event is recorded by different geological and archaeological means (bedrock fracturing
at 13 sites, fracturing of rock-carvings at 7 sites, liquefaction at two sites 43 km apart, and dating by radiocarbon,
archaeology, sea level history, etc).
Analyses of measured fracture pattern suggest that the epicentre of earthquake is to be searched for in vertical
movements of the local granite horst at Glimminge hallar.
The seismic intensity (on the IES scale) is likely to have been in the order of VIII-IX. The magnitude is esti-
mated at M 6.3 - 6.8.
The age can be fairly well established at 780-750 BC. The following quarrying episode at Branteträsk must be
older than 700 BC, and probably around 750-730 BC.
This investigation documents a new Late Holocene earthquake with a magnitude significantly higher than
those with the maximum magnitudes recorded by seismological instruments. Hence it should affect our hazard
assessment [5].
References
[1] Mörner, N.-A. (1991) Intense Earthquakes and Seismotectonics as a Function of Glacial Isostasy. Tectonophysics, 188,
407-410. http://dx.doi.org/10.1016/0040-1951(91)90471-4
[2] Mörner, N.-A. (2003) Paleoseismicity of Sweden—A Novel Paradigm. A Contribution to INQUA from Its Sub-Com-
mission on Paleoseismology at the 16th International INQUA Congress in Reno, Nevada, P&G print, 1-320.
[3] Mörner, N.-A. (2011) Paleoseismology: The Application of Multiple Parameters in Four Case Studies in Sweden.
Quaternary International, 242, 65-75. http://dx.doi.org/10.1016/j.quaint.2011.03.054
[4] Mörner, N.-A. (2009) Late Holocene Earthquake Geology in Sweden. Geological Society London Special Publications,
316, 179-188. http://dx.doi.org/10.1144/SP316.11
[5] Mörner, N.-A. (2013) Patterns in Seismology and Palaeoseismology, and Their Application in Long-Term Hazard As-

N.-A. Mörner
81
sessments—The Swedish Case in View of Nuclear Waste Management. Pattern Recognition in Physics, 1, 75-89.
http://dx.doi.org/10.5194/prp-1-75-2013
[6] Mörner, N.-A. (1969) The Late Quaternary History of the Kattegatt Sea and the Swedish West Coast: Deglaciation,
Shorelevel Displacement, Chronology, Isostasy and Eustasy. Sveriges Geologiska Undersökning, C-640, 1-487.
[7] Svedmark, E. (1908) Jordskalf i Sverige 1904-1906. P.A. Nordstedt & Söner, Stockholm, 124 p.
[8] Mörner, N.-A. (2012) Paleoseismic Fracturing of Rock Carvings 1000 BC in SE Sweden. INQUA-IGCP 567 Proceed-
ings, 3, 127-130.
[9] Mörner, N.-A. and Lind, B.G. (2013) The Bronze Age in SE Sweden—Evidence of Long-Distance Travel and Ad-
vanced Sun Cult. Journal of Geographical Sciences, 5, 78-91.
[10] Mörner, N.-A. and Lind, B.G. (2013) Verkehr, Handel, Sonnenkult und die Beobachtung der Sonnenbewegung im
Jahreslauf während der Bronzezeit in Südost Schweden. Ur-Europa Jahrbuch, 2013, 63-71.
[11] Mörner, N.-A. (2012) Geologisk Rapport. In: Lind, B.G., Ed., Från Branta Rör till Brantevik, Stjärnljusets Förlag,
Malmö, 29-32.
[12] Lind, B.G. and Mörner, N.-A. (2010) Mykenska och Feniciska spår på Österlen. Stjärnljusets Förlag, Malmö.
[13] Lind, B.G. (2012) Från Branta Rör till Brantevik. Stjärnljusets Förlag, Malmö.
[14] Althin, C.-A. (1945) Studium zu Bronxezeitlichen Felszeichnungen von Skåne. Gleerups, Lund.
[15] Mörner, N.-A. (2012) Strict Solar Alignment of Bronze Age Rock Carvings in SE Sweden. Journal of Archaeological
Science, 39, 3301-3305. http://dx.doi.org/10.1016/j.jas.2012.05.027
[16] Reicherter, K., Michetti, A.M. and Silva Barroso, P.V. (2009) Paleoseismology: Historical and Prehistorical Records of
Earthquake Ground Effects for Seismic Hazard Assessment. Geological Society London Special Publications, 316,
1-10. http://dx.doi.org/10.1144/SP316.1
[17] Mörner, N.-A. and Lind, B.G. (2012) Stonehenge Has Got a Younger Sister. Ales Stones Decoded. International
Journal of Astronomy and Astrophysics, 2, 23-27. http://dx.doi.org/10.4236/ijaa.2012.21004
[18] Mörner, N.-A. (2011) Rapport över sommarens arkeologiska utgrävningar vid Ales Stenar. Del 2: Geologiska Arbeten.
Rapport till RAÄ Länsstyrelsen i Skåne, 24.
[19] Erlström, M. and Kornfelt, K.-A. (2005) Berggrundskartan 2D Tomelilla SO, 2E Simrishamn SV, 1D Ystad NO & 1E
Örahusen NV, skala 1:50000. Sveriges Geologiska Undersökning, Af 215.
[20] Mörner, N.-A. (2013) Seismotectonics of the Swedish West Coast. Excursion Guide, July 27 IASPEI Paleoseismology
Excursion, 16 p.
[21] Gregersen, S. and Voss, P.H. (2014) Review of Some Significant Claimed Irregularities in Scandinavian Postglacial
Uplift on Timescales of Tens to Thousands of Years—Earthquakes in Denmark? Solid Earth, 5, 109-118.
http://dx.doi.org/10.5194/se-5-109-2014