**3. Discussion**

bedding. A lakebed at +27.4 m [24] shows no sign of a tsunami ingression. Therefore, the upper limit of the tsunami event is set at about 26.5 m, indicating a tsunami height in the order of 6

Several lakes and bogs in the region had been investigated before [24–26], but none of those studies recorded the occurrence of tsunamites despite the fact that they are quite clearly present in the lakes at +5.5, +10.8, +16.0 and +22.5 m [26], all later cored and dated by the author, as

Synchronizing the events recorded at Skålbo and Forsmark (**Figure 16**) implies a fall in tsunami

**Figure 16.** Synchronization of the tsunami events recorded at Skålbo (Hudiksvall) and at Forsmark (northern Uppland) at 2900 BP [23]; elevation of dated cores (red dots), sea level at 2900 BP (dark blue lines). The tsunami wave height of at least 12 m in Skålbo decreases to at least 6 m in Forsmark, i.e., a decrease of 6 m in 160 km. The basal trimming seems

In SW Sweden, there are evidence of a young paleoseismic event with local faulting of the Viking shoreline. This implies a faulting post-dating the formation of this shoreline, known as PTM-10, and dated at 1000-950 BP [1, 22, 27]. A fault offset of 1.1 m is recorded [1, 22].

It seems highly likely that this earthquake also set up a tsunami wave, which buried two Viking ships in the ancient harbour of Galtabäck [27]. A C14-date of the ship gave 1172 ±73 cal. years AD [28], which is quite close to a major historical earthquake event in 1174 as recorded in chronicles [29]. The covering and burying of the two ships in silt are indicative of a very rapid (instantaneous) process that took the ship owners by surprise, fully in line with the process of

height of 6 m over a distance of 160 km, which seems quite reasonable.

m (and a submarine trimming depth of about 20 m).

shown in **Figure 15**.

128 Tsunami

to go down at least 18 m below sea level.

**2.5. The AD 1174 event**

a tsunami event.

With a total of 17 separate tsunami events documented in Sweden after the Last Ice Age [1–4, 21], Sweden is a country of exceptionally high number of tsunami events. This is due to the fact that it represents an uplifted shelf environment [5] with sedimentary sequences—not least the varved clay—exposed on land where tsunami events can be documented in details and where their age can be determined with high precision [4].

It is most surprising that tsunamis have not yet been reported by other geologists in Sweden, Finland and Denmark, especially after the first report was brought out in 1995 [10] and 1996 [11]. The evidence is there in the field, just to observe, interpret and document.

In Norway, there are excellent records of the tsunami from the gigantic Storegga submarine slide [31, 32].
