N.-A. MÖRNER

Fig. 1. Map of Sweden with areas of recorded palaeoseismic activity (black dots 1-26; further discussed in M6rner 2003, 2004, 2005). Nine high-magnitude palaeoseismic events are recorded in the Late Holocene. Their ages in Cl4-years Be are given in black outside the map frames. A few place names referring to noise or fractured rock are given (outside the map frames). 'Svealand' refers to an area from where much of the Asa Creed owes its origin. It seems significant that so many earthquakes and place names are located just within this region.

Abstract: The Nordic Asa Creed talks about a giant wolf, "the Fenris Wolf', that was trapped and chained deep in the mountains. When he howled, the ground trembled violently and fractured. With the discovery of frequent high-magnitude palaeoseismic events in Sweden not only in de-glacial time but also in Late Holocene time, it seems both natural and logical that the Fenris tale refers to frightening earthquake events in the past. Once again tales and sagas have been shown to be rooted in facts.

In ancient times, natural phenomena were usually explained in terms of actions by gods. Phenomena such as earthquakes and volcanic eruptions were directly frightening; so too were ordinary phenomena like thunderstorms.

In the Norse mythology or the Nordic Asa creed, there are many examples of this. Thunderstorms were explained by the noise created by the god Thor throwing his hammer. The land uplift was explained by the giant Ymer slowly rising out of the sea. The end of our world--'Ragnarök" in the Asa crede--is described as a most terrible event when the ground fractures and rocks fragments are thrown higgledy-piggledy, like at a violent earthquake. Grant (2003) concludes that recent observations indicate that 'some of the tales were firmly rooted in fact'.

The Asa Creed originates in pre-Viking time. The mythological chronology given suggests that Odin and Thor arrived at Svealand in Late Iron Age and formed a new dynasty 'Ynglingaätten'. However, there is no discontinuity in the cultural evolution to account for this. On the contrary, there is continued cultural evolution back in time, to at least the Bronze Age and possibly even into the late Stone Age. The oldest place names owe their origin in the Bronze Age. The Asa Creed was written down in the thirteenth century AD by people on Iceland in their famous Edda (as recently reviewed by Grant 2003).

The Fenris Wolf

The god Loke had a son with the giantess Angrboda. The child took the form of a giant wolf--the Fenris Wolf--and became a threat even to the gods themselves (e.g. Grant 2003). Finally, the Fenris Wolf threatened to destroy the whole world. By magic, he was captured and chained deep in the mountains. When he howled, the ground and mountains trembled violently and deep fractures formed and rock fragments were thrown around.

Today, one might say; what a perfect description of a high-magnitude earthquake. Until recently, earthquakes above magnitude 5 on the Richter scale were not known from Sweden. Therefore, no one proposed a seismic origin for the story of the Fenris Wolf. It was simply sidelined as something less interesting. However, in recent years the situation has changed (Mörner 1994, 2003).

The new concept of a high palaeoseismic activity

During the last three decades, it has become increasingly clear that Sweden was subjected to strong seismic activity at the time of deglaciation some 9000-11000 radiocarbon years BP. From the notion that 'big earthquakes rather were the rule than the exception' (MiSrner 1985), there is an extensive palaeoseismic database (catalogue) including 54 magnitude 5-8 events (Mörner 2003). This catalogue even includes several magnitude 7 or 6-7 events in Late Holocene time, i.e. at times when they may have influenced not only the Norse mythology but also ancient place names (Mrmer 2003; M6rner & Strandberg 2003).

As Swedish palaeoseismicity has been presented elsewhere (Mörner 2003, 2004, 2005) this paper focuses on the Late Holocene events and their possible influence on place names, mythology and tales. In the last 5000 years, nine high-magnitude palaeoseismic events are recorded (Fig. 1). All these events are likely to have affected human life physically as well as spiritually. Effects such as faulting, fracturing, ground shaking, earth slides, tsunami waves, would have had considerable destructive effects. The 2000 Be event at Hudiksvall (site 9) set up a huge tsunami wave that washed in over land at least 20 m above sea level. The 2900 BP event at Forsmark (site 10) represents another huge tsunami that broke into lakes at least 25 m above sea level. The 3500 BP event at Marviken (site 12) caused a 5 km fracture, nine large slides (including the down-slope movement of a Bronze Age burial mound) and a local lake tsunami.

The 900 BP event on the Swedish west-coast includes a 1.0 m fault-scarp, rock shattering and liquefaction (with two Viking ships buried in sand by a possible tsunami). Our oldest place names are said to have originated in the Bronze Age. There are many names in Sweden that refer to sounds, noise or fractured rock. The Lake 'Marviken' name seems to refer to fractured rock which fits well with the effects of the 3500 BP event there. Lake 'Dunkern' refers to deep noise (an earthquake just at the spot is dated 8000 BP which seems too old to have affected the place name, but younger events may have followed in the same zone). Lake 'Hjälmaren' refers to 'the noisy' and it seems significant that the area is traversed by faults active in postglacial time (Mörner & Strandberg 2003). 'Päirve' in the far north is a Lapish name referring to noise from the underground. This area was struck by a violent seismotectonic even about 9000 BP (Lagerbäck 1979). This seems far too early for an imprint in the place name. However, there may have been subsequent activities on the fault. Much of the Nordic Asa creed seems to have originated in the region of 'Svealand' (termed 'Svenonian' by Tacitus, 79 AD, and 'Svitjod" in the Icelandic sagas), where the gods Thor and Odin were said to have emigrated and formed a new dynasty. Thus, it is interesting that we have so many traces of earthquakes just here (Fig. 1). All these facts make it highly likely that the tale of the Fenris Wolf owes its origin to actual natural phenomena; that is high-magnitude earthquakes in the Late Holocene (Fig. 1) and their associated effects (faulting, fracturing, shaking, liquefaction, tsunamis).

Conclusions

Until a few decades ago, we had no idea of the high frequency of de-amplitude earthquakes that struck Sweden in deglacial time. Therefore, no one had thought of the possibility that the tale of the Fenris Wolf could refer to actual earthquake events. With the novel findings of a high magnitude palaeoseismic activity in postglacial time including several high-magnitude events in the Late Holocene, it seems likely that the tale of the Fenris Wolf, in fact, provides a good description of palaeoseismic events in the past. This is further supported by a number of place names referring to sounds and fractured rock.

References

GRANT, J. 2003. An introduction to Viking Mythology. Quantum Publishing, Ltd.

LAGERBÄCK, R. 1979. Neotectonic structures in northern Sweden. Geologiska Frreningens i Stockhohn

Förhandlingar, 100, 263-269.

MÖRNER, N.-A. 1985. Paleoseismicity and geodynamics in Sweden. Tectonophysics, 117, 139-153.

MÖRNER, N.-A. 1994. The Fenris wolf and Swedish paleoseismicity. Bulletin of the INQUA Neotectonics

Commission, 17, 47.

MÖRNER, N.-A. 2003. Paleoseismicit)'of Sweden---a novel paradigm. A contribution to INQUA from its sub-commission on Palaeoseismology, ISBN-91-631-4072-1,320 pp., the P&G unit, Stockholm University.

MÖRNER, N.-A. 2004. Active faults in Fennoscandia, especially Sweden: primary structures and secondary effects. Tectonophysics, 380, 139-157.

MÖRNER, N.-A. 2005. An interpretation and catalogue for paleoseismicity in Sweden. Tectonophysics,

408, 265-307.

MÖRNER, N.-A. & STRANDBERG, S. 2003. Sjrnamnet Hjälmaren i geologisk belysning. Ortnamnssiillskapets i Uppsala Arsskrift, 79-82.