In the aftermath of the 2004 Indian Ocean (Sumatra-Andaman) tsunami, numerous survey teams investigated its effects on various locations across the Indian Ocean. However, these efforts were focused only on sites that experienced major destruction and a high death toll. As a consequence, some Indian Ocean coastal megacities were not examined. Among the cities not surveyed was Mumbai, the principal west coast port and economical capital of India with a population of more than 12 million. Mumbai is at risk of tsunamis from two major subduction zones in the Indian Ocean: the Sumatra–Andaman subduction zone (SASZ) and the Makran subduction zone (MSZ). As a part of the present study, we conducted a field survey of the 2004 Indian Ocean tsunami effects in Mumbai, analysed the available tide gauge records and performed tsunami simulations. Our field survey in 2018 January found run-up heights of 1.6−3.3 m in the Mumbai area. According to our analysis of tide gauge data, tsunami trough-to-crest heights in Okha (550 km to the north of Mumbai) and in Mormugao (410 km to the south of Mumbai) were 46 cm and 108 cm, respectively. Simulations of a hypothetical MSZ M_w 9.0 earthquake and tsunami, together with the M_w 9.1 Sumatra–Andaman earthquake and tsunami, show that the tsunami heights generated in Mumbai by an MSZ tsunami would be significantly larger than those generated by the 2004 Sumatra–Andaman tsunami. This result indicates that future tsunami hazard mitigation for Mumbai needs to be based on a potential large MSZ earthquake rather than an SASZ earthquake.

中文翻译：

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印度西海岸孟买地区2004年12月26日印度洋海啸的现场调查和数值模拟

在2004年印度洋（苏门答腊-安达曼）海啸之后，许多调查小组调查了其对印度洋各地的影响。但是，这些努力仅集中在遭受严重破坏和高死亡人数的地点。结果，没有检查一些印度洋沿海特大城市。在未经调查的城市中，孟买是印度的主要西海岸港口，也是印度的经济首都，人口超过1200万。孟买面临印度洋两个主要俯冲带海啸的危险：苏门答腊-安达曼俯冲带（SASZ）和马克兰俯冲带（MSZ）。作为本研究的一部分，我们对孟买2004年印度洋海啸影响进行了实地调查，分析了可用的潮汐仪记录并进行了海啸模拟。我们在2018年1月的实地调查发现孟买地区的上升高度为1.6−3.3 m。根据我们对潮汐仪数据的分析，在Okha（孟买以北550公里）和Mormugao（孟买以南410公里）的海啸波峰高度分别为46厘米和108厘米。假设的MSZ的模拟中号_W¯¯ 9.0级地震并引发海啸，与一起中号_W¯¯ 9.1苏门答腊-安达曼大地震和海啸，表明由MSZ海啸在孟买发生的海啸的高度会比由2004年的苏门答腊-安达曼海啸产生的那些显著更大。该结果表明，未来减轻孟买海啸危害的措施应基于潜在的MSZ大地震，而不是SASZ地震。