BALTIC wide-angle refraction and reflection profile

The deep seismic sounding BALTIC was conducted in 1982 to investigate the crustal structure of the Fennoscandian shield (Luosto et al. 1990). The 560 km (including Kostomuksha shots, main part 430 km) long survey profile runs northeast from the Gulf of Finland to Kostomuksha, Russia. Seismic sources were explosions shot at eight different shot points at sea, in shallow lakes and in a quarry. These shots were recorded by 48 seismic stations along the profile at an average receiver spacing of 2 km. The stations included 36 three-component stations: 16 “MARS 66”, 10 “ASS”, 10 “SN-PCM80” and 12 six-channel stations: 10 “Taiga-2” and 2 “SN-PCM-80”. The profile crosses the Wiborg rapakivi batholith, the Svecokarelian geosynclinal complex and the Archean basement complex in southeastern Finland. Two-dimensional crustal velocity models of the profile have been constructed by a trial-and-error ray tracing method. The model displays variability of 40 to more than 60 km in crustal thickness, the thickest crust being situated in the border region of the Svecofennian and Karelian domains. Three different velocity models are available for the BALTIC profile. The original P-wave velocity model was constructed by Luosto et al. (1990). New P- and S-wave models were published later by Janik (2010). Wide-angle P-wave sections are available from the profile measured at three different orientations. Janik, T. 2010. Upper lithospheric structure in the central Fennoscandian shield: Constraints from P- and S-wave velocity models and VP/VS ratio distribution of the BALTIC wide-angle seismic profile. Acta Geophysica 58: 543–586. Luosto, U., T. Tiira, H. Korhonen, I. Azbel, V. Burmin, A. Buyanov, I. Kosminskaya, V. Ionkis, and N. Sharov, 1990. Crust and upper mantle structure along the DSS Baltic profile in SE Finland. Geophysical Journal International 101: 89–110.

深地震测深（deep seismic sounding）BALTIC项目于1982年启动，旨在探究芬诺斯堪的亚地盾（Fennoscandian Shield）的地壳结构（Luosto等，1990）。该测线剖面全长560千米（含科斯托穆克沙炮点段，主体段长430千米），自芬兰湾向东北延伸至俄罗斯科斯托穆克沙。地震震源为爆炸激发，共设置8个炮点，分布于海域、浅湖及采石场内。沿剖面布设的48个地震台站记录了各炮点的震源信号，台站平均接收间距为2千米。台站类型涵盖36套三分量台站（three-component station）：16套MARS 66、10套ASS、10套SN-PCM80，以及12套六通道台站（six-channel station）：10套Taiga-2、2套SN-PCM-80。该剖面穿过芬兰东南部的维堡环斑花岗岩基、斯维科卡雷利亚地向斜系与太古宙基底岩系。研究人员通过试差射线追踪法构建了该剖面的二维地壳速度模型，模型显示地壳厚度介于40千米至60千米以上，空间变化特征显著，最厚地壳位于斯维科芬尼亚地块与卡雷利亚地块的交界区域。BALTIC测线共包含三套不同的速度模型：原始P波（P-wave）速度模型由Luosto等人于1990年构建；后续Janik于2010年发布了新的P波及S波（S-wave）速度模型；此外该剖面还提供了三种不同观测方位下的广角P波剖面数据。

Janik T. 2010. 芬诺斯堪的亚中部地盾的上层岩石圈结构：基于BALTIC广角地震剖面的P波、S波速度模型与VP/VS比（VP/VS ratio）分布约束. Acta Geophysica 58: 543–586.
Luosto U, Tiira T, Korhonen H, Azbel I, Burmin V, Buyanov A, Kosminskaya I, Ionkis V, Sharov N. 1990. 芬兰东南部DSS波罗的海剖面沿线的地壳与上地幔结构. Geophysical Journal International 101: 89–110.