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USGS2021

Karachi effects of the Makran earthquake and tsunami of November 1945: Mercury spilled, tide gauge impaired, seawalls overrun, boats displaced, mosque flooded

An earthquake and tsunamiI on November 28, 1945, sourced near the Makran coast of the Arabian Sea, disturbed port facilities and fishing villages to the east at Karachi Harbour. Seismic waves, some 300 kilometers from their Makran source, spilled mercury high in a lighthouse at Manora. One liter of the heavy, toxic liquid escaped from an annular trough in which one of the world’s heaviest assemblies of concentric glass prisms usually floated and revolved. Ensuing tsunami waves registered incompletely at a tide gauge, also at Manora. Prior blockage of a stilling well may have held down the recorded level of the first few waves. The highest wave went ungauged by breaking a mechanical connection between water levels and a graphing pencil. That highest wave overtopped seawalls of Keamari (Kiamari), according to newspaper accounts. The overflow reportedly flooded oil facilities, damaged 120 meters of Keamari Groyne, and destroyed a beacon on the groyne. By one account water apparently flowed from east to west in the bight south of Keamari. Interviews seven decades later elicited memories of displaced boats. In Karachi, a scion of a shipping family recalled observing, a few days after the tsunami, a pair of military landing craft atop Keamari wharves beside which the craft had been berthed, he said, as ferries serving schools of the Royal Indian Navy. In Gujarat, a former sailor and port official told of feeling the tsunami suddenly lift an ocean-going dhow that had been grounded for hull cleaning near Baba Island. Others interviewed testified to flooding in fishing villages on Baba and Bhit islands. Three independent accounts told of water entering a Bhit Island mosque. Likely water levels at the overrun seawalls, stranded landing craft, and flooded mosque all exceed the maximum wave height gauged at Manora. A tsunami like the one in 1945 would today encounter more people and developed property in Karachi’s port areas. The population of port villages has increased tenfold or more, as has the tonnage of imports and exports.

Karachi↗

USGS2014

Elders recall an earlier tsunami on Indian Ocean shores

Ten years on, the Indian Ocean tsunami of 26 December 2004 still looms large in efforts to reduce coastal risk. The disaster has spurred worldwide advances in tsunami detection and warning, tsunami-risk assessment, and tsunami awareness [Satake, 2014]. Nearly a lifetime has passed since the northwestern Indian Ocean last produced a devastating tsunami. Documentation of this tsunami, in November 1945, was hindered by international instability in the wake of the Second World War and, in British India, by the approach of independence and partition. The parent earthquake, of magnitude 8.1, was widely recorded, and the tsunami registered on tide gauges, but intelligence reports and newspaper articles say little about inundation limits while permitting a broad range of catalogued death tolls. What has been established about the 1945 tsunami falls short of what's needed today for ground-truthing inundation models, estimating risk to enlarged populations, and anchoring awareness campaigns in local facts. Recent efforts to reduce coastal risk around the Arabian Sea include a project in which eyewitnesses to the 1945 tsunami were found and interviewed (Fig. 1), and related archives were gathered. Results are being made available through UNESCO's Indian Ocean Tsunami Information Center in hopes of increasing scientific understanding and public awareness of the region's tsunami hazards.

Eos, Earth and Space Science News↗