Submitted:
21 April 2025
Posted:
22 April 2025
Read the latest preprint version here
Abstract
Keywords:
Introduction
Methodology
Results

| M < 7 |
| 2 * N + 14 * n-a where a > 0 => decrease as M value rises |
| 7 < M < 7.8 |
| 2 * N + 14 * (n0) => linear decrease as M value rises |
| M > 7.8 |
| 2 * n + 14 * (na), where a > 0 => logarithmic decrease as M value rises |
| “import numpy as np |
| def earthquake_probability(rate, time_years): |
| “““ |
| Calculate the probability of at least one event occurring in a given time period |
| using the Poisson process. |
| Parameters: |
| rate (float): Average event rate (events per year). |
| time_years (float): Time period in years. |
| Returns: |
| float: Probability of at least one event occurring. |
| “““ |
| return 1 - np.exp(-rate * time_years) |
| # Recurrence intervals for each category (in years) |
| recurrence_M7_5 = 80 # M7.5+ earthquakes occur once every 80 years |
| recurrence_M8 = 220 # M8+ earthquakes occur once every 220 years |
| recurrence_M8_5 = 700 # M8.5+ earthquakes occur once every 700 years |
| # Calculate λ for each category |
| lambda_M7_5 = 1 / recurrence_M7_5 |
| lambda_M8 = 1 / recurrence_M8 |
| lambda_M8_5 = 1 / recurrence_M8_5 |
| print(“Poisson rate parameters (λ):”) |
| print(“λ for M7.5+ earthquakes: {:.6f} events/year”.format(lambda_M7_5)) |
| print(“λ for M8+ earthquakes: {:.6f} events/year”.format(lambda_M8)) |
| print(“λ for M8.5+ earthquakes: {:.6f} events/year”.format(lambda_M8_5)) |
| # Define time intervals (years) for probability calculations |
| time_intervals = [1, 5, 10, 20, 50, 100] |
| # Calculate and print probabilities for each earthquake category |
| def print_probabilities(mag_label, lam): |
| print(“\nProbabilities for {} earthquakes:”.format(mag_label)) |
| for t in time_intervals: |
| prob = earthquake_probability(lam, t) |
| print(“ Next {:3d} years: {:6.2f}%”.format(t, prob * 100)) |
| print_probabilities(“M7.5+”, lambda_M7_5) |
| print_probabilities(“M8+”, lambda_M8) |
| print_probabilities(“M8.5+”, lambda_M8_5)” |
Discussion
| Country / Region | Estimated Maximum Mercalli-Scale Intensity for an M8.5 Seismic Event in Vrancea |
|---|---|
| Romania | Epicentral areas: X-XI; Major cities: IX-X |
| Moldova | Around VIII |
| Bulgaria | Northern regions: VIII-IX; Rest of the country: VII-VIII |
| Western Ukraine | VI-VIII |
| Serbia | VII-VIII |
| European Turkey | VI-VII |
| Hungary | V-VII |
| Czech Republic & Slovakia | V-VI |
| Austria and Eastern Switzerland | V-VI |
| Poland | V-VI |
| Italy | Northeastern regions: V-VI; Rest of the country: Generally III-IV |
| Greece | Around VI |
| France | Eastern regions: IV-V; Rest of the country: III-IV |
| Germany | Eastern regions: About V; Rest of the country: Around IV |
| United Kingdom | II-III |
| Republic of Ireland | II-III |
| Spain | II-III |
| Portugal | Around II |
| Belgium, Netherlands and Denmark | About III-IV |
| Scandinavian Countries | Around II |
| Baltic Countries | About III |
| European Russia | III-IV |
| Mercalli Scale (MMI) | Perception | Description |
|---|---|---|
| I | Not felt | The earthquake is only felt by very few people, under highly select circumstances. |
| II | Weak | The earthquake is felt by a few people during resting time, particularly residents of higher levels of multi-story buildings. Most likely not recognised as an earthquake. |
| III | Weak | Felt visibly by persons located indoors, particularly on higher levels of multi-story buildings. Numerous people may not recognise it as an actual earthquake. |
| IV | Light | Felt indoors by numerous people, and outdoors by much fewer people. Bathroom and kitchen items, doors and windows may be moved and/or slightly affected. |
| V | Moderate | The event is felt by almost all local residents and visitors, and many people resting become awake. Wardrobes, bathroom and kitchen items, doors and windows are moved and some of the smaller items are broken and overturned in the process. |
| VI | Strong | Felt by everyone, and many people exit buildings in a panic mode. Some heavy elements of apartments that include wardrobes and even slightly broken doors are moved. Windows and other outside elements of buildings may face slight cracks and damages. |
| VII | Very Strong | Local residents and visitors find it difficult to keep their balance, with damages occurring even in well-assembled and designed buildings, with more significant effects upon older buildings. A number of houses can have their chimneys broken in the process. |
| VIII | Severe | Particularly well-assembled and designed buildings face little damage, whilst others face notable damages and some buildings may partially collapse in the process. Several chimes and some factory stacks also face collapse. |
| IX | Violent | The local population is under general panic. Well-assembled and designed buildings face notable damages and many other buildings face either complete collapse or disturbed foundations. Cracks suddenly appear in the ground. |
| X | Extreme | The majority of buildings face total collapse, including some well-constructed and assembled ones. Several, considerable fissures appear in the ground, with several vehicles and even some buses and trucks becoming “swallowed” in the process. The visibility can be decreased in remote areas, where a few closely-located multi-story buildings have collapsed. |
| XI | Extreme | Only a few buildings remain intact. Many bridges are torn apart and destroyed. Large-scale breaks in the ground appear, with many vehicles, buses and trucks falling into them. Electricity is likely cut off in broad areas, and heat and running water becomes broadly unavailable. The visibility becomes lower in local areas. |
| XII | Extreme | The earthquake has catastrophic effects upon the local and broader areas, with utter collapse observed in the general, big image of the urban environment. The ground moves in a wavy manner, leading and contributing to the production of numerous, broad fissures. Voluminous items and objects are thrown into the air at altitudes of tens and few hundred feet, and the visibility becomes low. |
| Distance from the epicentre (from the surface-level perspective) | Risk of dam collapse following a Magnitude 8+ earthquake | Risk of dam collapse following a Magnitude 8.5+ earthquake |
|---|---|---|
| Close river dams (<100 km) | Siriu, Valea Uzului: 50-80% | Siriu, Valea Uzului: 70-90% |
| Medium-distance river dams (100-200 km) | Izvorul Muntelui, Bolboci, Lacul Morii: 30-60% | Izvorul Muntelui, Bolboci, Lacul Morii: 50-80% |
| Large-distance river dams (>200 km) | Vidra, Vidraru: 25-40% Gilau I: 10-25% |
Vidra, Vidraru: 45-60% Gilau I: 30-45% |
Conclusions
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