有些国家对地震免疫吗?

The Myth: Some Countries Are Completely Safe from Earthquakes

A natural consequence of the mental model linking earthquakes exclusively to famous fault systems like the San Andreas or the Japan Trench is the belief that countries located far from these systems are earthquake-proof. People in the United Kingdom, Australia, central Africa, or the American Midwest sometimes express surprise when earthquakes occur in their regions, having assumed immunity. This assumption is a myth, though like most myths it has a grain of truth: earthquake hazard does vary enormously by location, and some regions face dramatically higher risk than others.

Where the Grain of Truth Lies

The 环太平洋火山带环绕太平洋的马蹄形地带，全球约90%的地震发生于此。该地带绵延40,000公里，包含452座火山。 — the chain of 俯冲带一个构造板块潜入另一板块之下并进入地幔的区域。俯冲带产生世界上最大的地震（8.5级以上），并伴有深海沟和火山弧。 systems, island arcs, and continental collision zones encircling the Pacific Ocean — hosts approximately 90% of the world's earthquakes by count and an even higher fraction by total energy release. Japan, the Philippines, Indonesia, New Zealand, Chile, Peru, Colombia, Mexico, the western United States, and Canada's Pacific coast face seismic hazard that is orders of magnitude higher than continental interiors. The Himalayan collision zone (India, Nepal, Pakistan, Tibet), the Mediterranean (Italy, Greece, Turkey, Iran), and the Caribbean complete the picture of the most seismically active regions.

Countries genuinely far from all active 板块边界两个构造板块相接的边缘。大多数地震、火山喷发和造山运动都发生在板块边界。共有汇聚型、离散型和转换型三种类型。 systems and without significant intraplate seismic history do face dramatically lower hazard. Brazil, most of Australia, Scandinavia, and central sub-Saharan Africa have very low background seismicity and very long recurrence intervals for even moderate earthquakes. Low hazard is not zero hazard, but the expected frequency of damaging events may be one per several hundred to several thousand years.

Countries That Think They're Safe But Aren't

The United Kingdom experiences hundreds of small earthquakes annually, mostly too small to be felt, but M4-5 events occur occasionally. The 1884 Colchester earthquake (estimated M4.6) caused widespread damage. The 2008 Market Rasen earthquake (M5.2) was felt across much of England. While UK seismic hazard is genuinely low in global context, the assumption of complete immunity has sometimes led to underinvestment in seismic considerations for critical infrastructure.

Australia is often cited as a "safe" continent, and its background seismicity is indeed low. But the 1989 Newcastle earthquake (M5.6) killed 13 people and caused approximately $4 billion in damage — in a city that had no seismic design requirements because it was assumed to be earthquake-free. Australia has now revised its national building codes to include seismic provisions for all regions.

Intraplate seismicity affects regions that have no obvious connection to active 构造板块地球岩石圈中不断移动、漂浮、有时发生断裂的巨大板块。共有7个主要板块和约8个次要板块，它们之间的相互作用引发了绝大多数地震。 boundaries. The New Madrid Seismic Zone in the central US, the Wabash Valley seismic zone in Illinois and Indiana, the Charlevoix seismic zone in Quebec, and the Western Quebec seismic zone all represent elevated intraplate hazard far from any plate boundary. These regions have 地震重现间隔特定断层上相邻两次大地震之间的平均时间间隔，通过古地震学研究和历史记录估算得出。卡斯凯迪亚俯冲带的重现间隔约为500年。 estimates for large earthquakes of hundreds to thousands of years — long enough that the hazard is often forgotten between events — but the hazard is real.

The Role of 诱发地震活动由水力压裂、废水回注、采矿或水库蓄水等人类活动引发的地震。大多数震级较小（低于4级），但部分曾超过5.5级。

Human activities have created seismic hazard where essentially none existed naturally. As documented in detail in the induced seismicity guide, oil and gas wastewater disposal has driven earthquake rates to historically unprecedented levels in Oklahoma, Kansas, and parts of Texas. These are regions in the stable continental interior, far from any active 板块边界两个构造板块相接的边缘。大多数地震、火山喷发和造山运动都发生在板块边界。共有汇聚型、离散型和转换型三种类型。, that now face elevated earthquake risk as a direct consequence of energy production practices. The concept of "immune countries" or "immune regions" is further undermined when human activities can generate seismic hazard in geologically quiet areas.

Countries expanding geothermal energy production — including Iceland, New Zealand, the United Kingdom, Germany, and Switzerland — have encountered induced seismicity challenges. Switzerland halted a Basel geothermal project after induced M3.4 shaking; the Pohang geothermal project in South Korea is strongly linked to a 2017 M5.5 earthquake that injured 135 people and caused significant structural damage. The global expansion of renewable energy and unconventional oil production means that "geologically quiet" does not automatically mean "seismically safe" when human infrastructure is present.

Historical Records and Forgotten Earthquakes

Many countries that consider themselves earthquake-immune have simply forgotten their seismic history because the relevant events occurred before modern memory. Portugal was struck by the 1755 Lisbon earthquake (estimated M8.5-9.0), which killed 30,000-50,000 people, destroyed most of Lisbon, and generated a tsunami that struck the Moroccan coast. Portugal sits at the convergence of the Eurasian and African plates — the same tectonic boundary responsible for ongoing seismicity in Morocco, Algeria, and the Mediterranean — but this hazard receives far less attention than the Pacific rim.

Northwestern China, the Middle East, and North Africa occupy the diffuse collision zone between the African, Arabian, and Eurasian plates — a seismic hazard zone that has produced devastating historical earthquakes in Syria, Turkey, Iran, and Egypt. The 2023 Kahramanmaras earthquake sequence in Turkey (M7.8 and M7.7) killed over 55,000 people, a tragedy in a region that has experienced major earthquake disasters for millennia.

What "Low Hazard" Means for Policy

Genuinely low-hazard regions face a specific policy challenge: the long recurrence intervals between damaging events mean that the institutional memory of past earthquakes fades, hazard is discounted in planning decisions, building codes may lack seismic provisions, and emergency management agencies may have no earthquake experience. When an event does occur — inevitably, eventually — the consequences can be disproportionately large because of accumulated vulnerability.

The Australian Newcastle experience, the 1755 Lisbon experience, and the repeated experience of previously "safe" cities being surprised by intraplate or border-region earthquakes all point to the same policy lesson: baseline seismic awareness, inclusion of seismic provisions in building codes proportional to hazard probability, and maintenance of institutional knowledge about earthquake risk should be universal, not reserved for regions adjacent to famous fault zones.

The Right Mental Model

The right framing is not "safe countries vs. unsafe countries" but rather "current expected annualized loss" — a probabilistic quantity that varies continuously across space and incorporates both hazard and vulnerability. Japan has very high annualized expected losses from earthquakes. Australia has very low but non-zero expected losses. Both countries need seismic considerations in their building codes and emergency planning; the appropriate scale of investment differs by orders of magnitude. "Immune" is not a useful scientific concept in earthquake risk assessment.