Reconstruction of the 1755 Earthquake McGill University 2011 F-X Capelle – Eric Munro – Adrien Iredale

Table of Content 1) Reconstruction based on geophysical data Tectonic setting Generated tsunami wave 2) Local destruction and aftershocks Post 1755 earthquakes 1 st interests in seismology 3) Impact on European culture and society Colonial ambitions restricted Cultural repercussions

Part 1 – Reconstruction of 1755 earthquake based on geophysical data

Magnitude Felt area radii  Mw 8.7 ± 0.4 Compare to 1969 earthquake tsunami wave height Energy release 40 times greater than the 1969 earthquake (Mw 7.9)  Implies a 1755 magnitude between 8.9 and 9.4

The Tectonic Setting

Summary of proposed sources Figure 1: Principle tectonic structures identified around SW Iberian continental margin

Duration and Complexity – Ground Motion Figure 2 – Reported Durations of the 1755 mainshock

Macroseismic Field Figure 3 – Macroseismic MSK intensities of the 1755 mainshock

Farfield long period affects Malaga: “tops of high buildings fell” Milan and Amsterdam: “oscillating chandeliers from cathedral roofs” Across Holland and Germany: “many rivers and canals were sent into pronounced oscillation” Scotland: “water levels rose and fell 0.8m for a period of 10 minutes”… “so violent to threaten destruction to some houses built on lake shores”

Coseismic deformation Figure 4 – Potential coseismic deformation from the 1755 earthquake

The Local Tsunami Figure 5 – Tsunami arrival times after the 1755 mainshock

The Farfield Tsunami Figure 6 – Farfield tsunami arrival time from 1755 mainshock

Part 2 – Local destruction and aftershocks

Aftershocks and Triggered Earthquakes -Many aftershocks in the hours and days to follow. -Algiers, Algeria; city and harbour severely damaged. -November 27 th, 1755 Meknes, Morocco -MSK IX-X, Mw March 31 st, MSK IX, Mw 8.5 (inferred)

-2.4m high Tsunami in Cork, Ireland -1.9m high Tsunami in Cornwall, England -1.2m high Tsunami in Barbados 3 min 2.5 min 3 min 5 min

Local Damage Mw 8.7 +/- 0.4, MSK IX-X -City of 240,000, and deaths between 10,000 and 100, % of the buildings were destroyed. -Art, literature, and explorations records destroyed. -Restricted colonial ambitions.

The Fire - Caused by thousands of candles and unattended cooking fires - Spread fast across small streets - Lack of rescue organization - Destroyed lots of important buildings that were not affected by the earthquake

The Start of Seismology The Prime Minister designed a national survey concerning the earthquake. Cataloging of times, locations, and physical effects began. Construction of the first earthquake resistant buildings.

Part 3 – Impact on European culture and society

Loss of Colonial Presence - Economic effort went to re-building coastal cities, not colonies. - Loss of grounds in colonies, later defeats against Spain.

First Earthquake Theories Kant: First non-religious earthquake theories, including movement of gases in caves.

The Earthquake in European Culture Age of Enlightenment: Developing philosophy leading to the modern human rights, with the distinct separation of God from life. Voltaire’s Candide: Denying a perfect world created by God J.J. Rousseau: Support for his theory that man is naturally good, and that society corrupts him.

References -R.A. Hindson, C. Andrade (1999), Sedimentation and hydrodynamicprocesses associated with the tsunami generated by the 1755 Lisbon earthquake, Quaternary International, Vol. 56, pp A.C. Johnson (1996), Seismic moment assessment of earthquakes in stable continental regions—III. New Madrid , Charleston 1886 and Lisbon 1755, Geophysical Journal International, Vol. 126, pp J.T. Kozak, C.D. James (1998), Historical depictions of the 1755 Lisbon Earthquake, NISEE, University of Berkeley. - N. Zitinelli, F. Chierici, R.Sartori and L.Torelli (1999), The tectonic source of the 1755 Lisbon earthquake and tsunami, Annali de geofisica, Vol. 42, pp